This file was created by the TYPO3 extension publications --- Timezone: CEST Creation date: 2026-05-09 Creation time: 11:58:26 --- Number of references 43 article ma2021review 2021 Earthquake Geology and Tectonophysics around Eastern Tibet and Taiwan Springer 63-82 Kuo-Fong Ma article Hirono2020 Article 2020 10.1038/s43247-020-0004-z Communications Earth and Environment 1 1 https://www.scopus.com/inward/record.uri?eid=2-s2.0-85103360895&doi=10.1038%2fs43247-020-0004-z&partnerID=40&md5=6998fab0290f96ea78b48108f0aa5510 Cited by: 7; All Open Access, Gold Open Access Tetsuro Hirono Shunya Kaneki Tsuyoshi Ishikawa Jun Kameda Naoya Tonoike Akihiro Ito Yuji Miyazaki article Hillers2014121 Using seismic noise based monitoring techniques we find that seismic velocity variations (dv/v) observed with the borehole array of the Taiwan Chelungpu-fault Drilling Project (TCDP) are controlled by strong precipitation events associated with the Madden-Julian Oscillation (MJO), a dynamic intraseasonal atmospheric pattern in the tropical atmosphere. High-frequency noise (>1 Hz) excited by steady anthropogenic activity in the vicinity of the TCDP allows daily resolution of dv/v time series. Relatively large fluid discharge properties control the equilibration of the ground water table and hence seismic velocities on time scales smaller than the average precipitation recurrence interval. This leads to the observed synchronous 50-80 day periodicity in dv/v and rainfall records in addition to the dominant annual component. Further evidence for the governing role of hydraulic properties is inferred from the similarity of observed dv/v timing, amplitude, and recovery properties with dv/v synthetics generated by a combined model of ground water table changes and diffusive propagation of seismic energy. The lapse time (τ) dependent increase of dv/v amplitudes is controlled by the sensitivity of the diffuse wave field sampled at 1100 m depth to shallower water level fluctuations. The significant vertical offset between stations and water level explains the direct τ dependence which is opposite to the trend previously inferred from measurements at the surface. © 2014 Elsevier B.V. 2014 English 0012821X 10.1016/j.epsl.2014.01.040 Earth and Planetary Science Letters 391 121-127 Institut des Sciences de la Terre, Université Joseph Fourier, CNRS, Grenoble, France; Department of Earth Sciences, National Central University, Jhongli City, Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-84893931995&doi=10.1016%2fj.epsl.2014.01.040&partnerID=40&md5=b1bd39720e14a649b5831cc07bfd0a97 cited By 45 G. Hillers M. Campillo K.-F. Ma article Hillers2012 The Taiwan Chelungpu-fault Drilling Project (TCDP) installed a vertical seismic array between 950 and 1270 m depth in an active thrust fault environment. In this paper we analyze continuous noise records of the TCDP array between 1 and 16 Hz. We apply multiple array processing and noise correlation techniques to study the noise source process, properties of the propagation medium, and the ambient seismic wave field. Diurnal amplitude and slowness patterns suggest that noise is generated by cultural activity. The vicinity of the recording site to the excitation region, indicated by a narrow azimuthal distribution of propagation directions, leads to a predominant ballistic propagation regime. This is evident from the compatibility of the data with an incident plane wave model, polarized direct arrivals of noise correlation functions, and the asymmetric arrival shape. Evidence for contributions from scattering comes from equilibrated earthquake coda energy ratios, the frequency dependent randomization of propagation directions, and the existence of correlation coda waves. We conclude that the ballistic and scattered propagation regime coexist, where the first regime dominates the records, but the second is weaker yet not negligible. Consequently, the wave field is not equipartitioned. Correlation signal-to-noise ratios indicate a frequency dependent noise intensity. Iterations of the correlation procedure enhance the signature of the scattered regime. Discrepancies between phase velocities estimated from correlation functions and in-situ measurements are associated with the array geometry and its relative orientation to the predominant energy flux. The stability of correlation functions suggests their applicability in future monitoring efforts. Copyright 2012 by the American Geophysical Union. 2012 English 21699313 10.1029/2011JB008999 Journal of Geophysical Research: Solid Earth 117 Blackwell Publishing Ltd Institut des Sciences de la Terre, Université Joseph Fourier, CNRS, FR-38041 Grenoble, France; Department of Earth Sciences, Institute of Geophysics, National Central University, Jhongli, Taiwan 6 ambient noise; borehole; coda; correlation; drilling; geophysical array; in situ measurement; numerical model; seismic source; seismic wave; signal-to-noise ratio; wave field; wave propagation; wave scattering, Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-84861854258&doi=10.1029%2f2011JB008999&partnerID=40&md5=e03767988b6e09bb8501ef47dd4c2dc2 cited By 19 G. Hillers M. Campillo Y.-Y. Lin K.-F. Ma P. Roux article Wang201276 The attenuation factor, Q, at a fault zone is an important parameter for understanding the physical properties. In this study, we investigated the Q value of the Chelungpu Fault, the main rupture of the Mw 7.6 Chi-Chi earthquake, using the 7-level TCDP borehole seismometer array (TCDPBHS). The TCDPBHS was deployed at depths from 945 to 1270m throughout the 1999 ruptured slip zone at 1111m. Three borehole seismometers (BHS1-BHS3) were placed in the hanging wall, and the remaining three (BHS5-BHS7) were placed in the foot wall, with BHS4 near the slip zone. The configuration allowed us to estimate the Q-structure of the recent ruptured fault zone. In this study, we estimated Q values between BHS1 and BHS4, Qs 1 (Qp 1) at the fault zone and between BHS4 to 2km in depth, Qs 4 (Qp 4) beneath the fault zone. We utilized two independent methods, the spectral ratio and spectral fitting analyses, for calculating the Q value of Qs 1 (Qp 1) in order to provide a reliability check. After analyzing 26 micro-events for Qs and 17 micro-events for Qp, we obtained consistent Q values from the two independent methods. The values of Qs 1 and Qp 1 were 21-22 and 27-35, respectively. The investigation for the value of Qs 4 was close to 45, and Qp 4 was 85. These Qp and Qs values are quiet consistent with observations obtained for the San Andreas Fault at the corresponding depth. A low Qs 1 value for the recent Chelungpu Fault zone suggests that this fault zone has been highly fractured. Qs values within the Chelungpu Fault, similar to those within the San Andreas Fault, suggest that the Q structure within the fault zone is sedimentary rock independent. However, the possible existence of fluids, fractures, and cracks dominates the attenuation feature in the fault zone. © 2011 Elsevier B.V. 2012 English 00401951 10.1016/j.tecto.2011.12.027 Tectonophysics 578 76-86 Institute of Geophysics, National Central University, Chungli, Taiwan Chelungpu Fault; Drilling projects; Fault-zone attenuation; Qp; Qs; Seismic attenuation, Seismographs; Strike-slip faults, Seismology, borehole; Chi-Chi earthquake 1999; earthquake rupture; fault zone; footwall; San Andreas Fault; sedimentary rock; seismic attenuation; seismograph; slip, Chelungpu Fault Zone; Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-84862166220&doi=10.1016%2fj.tecto.2011.12.027&partnerID=40&md5=840c9e0fc86779d843e12f2b7f0742c5 cited By 11 Y.-J. Wang Y.-Y. Lin M.-C. Lee K.-F. Ma article Lin2012665 Microearthquakes with magnitude down to 0.3 were detected by the Taiwan Chelungpu-fault Drilling Project Borehole Seismometers (TCDPBHS). Despite the large coseismic slip of 12m at the drill site during the 1999 Chi-Chi earthquake, our studies show very little seismicity near the TCDPBHS drill site 6 yr after the Chi-Chi main shock. The microearthquakes clustered at a depth of 9-12 km, where the Chelungpu thrust fault turns from a 30° dipping into the horizontal decollement of the Taiwan fold-and-thrust tectonic structure. Continuous GPS surveys did not observe post-slip deformation at the larger slip region and no seismicity was observed near the drill site. Therefore we suggest that the thrust belt above the decollement is locked during this interseismic period. We further investigated source parameters of 242 microearthquakes by fitting ω -2-shaped Brune source spectra to our observation data using a frequency-independent Q model. We find that the static stress drop increases significantly with increasing seismic moment. However, due to the intense debate on this topic of scaling-relations and the related self-similarity of earthquakes, we further improve the data analysis and correct for path and site effects using the Projected Landweber Deconvolution (PLD) method for events within some clusters. The PLD method analyses the source time functions of the larger and the smaller event by an iterative technique. As a result we received source dimensions and stress drops of larger events including path and site effect corrections. The results from the PLD method are less scattered and also show a positive relation between static stress drop and seismic moment. We find a similar positive trend for the apparent stress scaling with seismic moment. © 2012 The Authors Geophysical Journal International © 2012 RAS. 2012 English 0956540X 10.1111/j.1365-246X.2012.05513.x Geophysical Journal International 190 665-676 Department of Earth Sciences, Institute of Geophysics, National Central University, Jhongli, Taiwan; NORSAR, Kjeller, Norway 1 Apparent stress; ChiChi earthquake; Coseismic slips; Drill sites; Drilling projects; Earthquake source; GPS survey; Inter-seismic periods; Iterative technique; Main shock; Method analysis; Micro-earthquakes; Observation data; Seismic moment; Seismotectonics; Self-similarities; Site effects; Source dimensions; Source parameters; Source time functions; Static stress; Stress drop; Tectonic structure; Thrust belts; Thrust faults, Boring; Drills; Drops; Faulting; Seismographs, Earthquakes, Chi-Chi earthquake 1999; decollement; deformation; earthquake magnitude; fold and thrust belt; microearthquake; seismic moment; seismicity; seismograph; seismotectonics; source parameters; tectonic structure; thrust fault, Chelungpu Fault Zone; Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-84862209007&doi=10.1111%2fj.1365-246X.2012.05513.x&partnerID=40&md5=b052a2d4145ba327e71823f826f5ca29 cited By 13 Y.-Y. Lin K.-F. Ma V. Oye article Haimson201145 An extensive true triaxial testing program was carried out on core samples from three ICDP-sponsored deep scientific boreholes, KTB (Germany), SAFOD (United States), and TCDP (Taiwan). The three rocks differ in the processes that formed them and in many of their mechanical properties. However, all three rocks exhibited similar failure mechanism, in which induced or reopened microcracks are primarily aligned with the σ1-σ2 plane, and the developed fault is steeply inclined in the σ3 direction. Rock strength in all tested rocks increases with σ2 when σ3 is kept constant. Thus, the common Mohr-type criteria, which ignore the effect of σ2, typically underestimate rock strength. Rather a 3D criterion that involves all three principal stresses represents well experimental results. Fracture plane slope for the same σ3 steepens as σ2 rises, contrary to Mohr-type criteria. With respect to deformation, the onset of dilatancy increases with σ2. In conclusion, true triaxial tests conducted on cores from three scientific boreholes, revealed important details of mechanical behavior not otherwise observed in conventional triaxial tests. In addition, they show mechanical behavior similarities as related to σ2 effect regardless of rock type. © 2010 Elsevier B.V. 2011 English 00401951 10.1016/j.tecto.2010.10.011 Tectonophysics 503 45-51 Dept. of Materials Science and Engineering and the Geological Engineering Program, University of Wisconsin, 1509 University Avenue, Madison, WI, 53706, United States 1-2 Dilatancy; Fault angle; Scientific boreholes; True triaxial strength; True triaxial testing, Deformation; Mechanical engineering; Mechanical properties; Rock mechanics; Testing, Rocks, borehole; deformation; dilatancy; failure mechanism; mechanical property; microcrack; rock mechanics; triaxial test, Germany; Taiwan; United States https://www.scopus.com/inward/record.uri?eid=2-s2.0-79954642377&doi=10.1016%2fj.tecto.2010.10.011&partnerID=40&md5=15821fb817ddead48ed292c695ef54d2 cited By 21 B. Haimson article NoAuthor2010299 2010 English 00401951 10.1016/j.tecto.2010.06.013 Tectonophysics 492 299-301 1-4 https://www.scopus.com/inward/record.uri?eid=2-s2.0-84755161274&doi=10.1016%2fj.tecto.2010.06.013&partnerID=40&md5=7d2e41223de04ed884c3af242bf9a1f4 cited By 1 article Dong20101141 We utilize an integrated permeability and porosity measurement system to measure the stress dependent permeability and porosity of Pliocene to Pleistocene sedimentary rocks from a 2000m borehole. Experiments were conducted by first gradually increasing the confining pressure from 3 to 120MPa and then subsequently reducing it back to 3MPa. The permeability of the sandstone remained within a narrow range (10-14-10-13m2). The permeability of the shale was more sensitive to the effective confining pressure (varying by two to three orders of magnitude) than the sandstone, possibly due to the existence of microcracks in the shale. Meanwhile, the sandstone and shale showed a similar sensitivity of porosity to effective pressure, whereby porosity was reduced by about 10-20% when the confining pressure was increased from 3 to 120MPa. The experimental results indicate that the fit of the models to the data points can be improved by using a power law instead of an exponential relationship. To extrapolate the permeability or porosity under larger confining pressure (e.g. 300MPa) using a straight line in a log-log plot might induce unreasonable error, but might be adequate to predict the stress dependent permeability or porosity within the experimental stress range. Part of the permeability and porosity decrease observed during loading is irreversible during unloading. © 2010 Elsevier Ltd. 2010 English 13651609 10.1016/j.ijrmms.2010.06.019 International Journal of Rock Mechanics and Mining Sciences 47 Elsevier BV 1141-1157 Graduate Institute of Applied Geology, National Central University, No. 300, Jungda Road, Jungli, Taoyuan 32001, Taiwan; Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima, Japan; Institute of Geophysics, National Central University, Jungli, Taoyuan, Taiwan; Department of Geosciences, National Taiwan University, Taipei, Taiwan; Department of Geophysics, Stanford University, California, United States 7 Digital storage; Mechanical permeability; Microcracks; Porosity; Road construction; Rock pressure; Sandstone; Unloading, Confining pressures; Effective pressure; Log-log plots; Permeability and porosities; Stress dependence; Stress history; Stress-dependent; Three orders of magnitude, Shale https://www.scopus.com/inward/record.uri?eid=2-s2.0-77956652607&doi=10.1016%2fj.ijrmms.2010.06.019&partnerID=40&md5=e5b4dc8a7b4028d15de6f2c13b360c12 cited By 385 J.-J. Dong J.-Y. Hsu W.-J. Wu T. Shimamoto J.-H. Hung E.-C. Yeh Y.-H. Wu H. Sone article Wang2010655 On 20 September 1999, the Ms 7.6 Chi-Chi earthquake ruptured the Chelungpu fault in central Taiwan. After the earthquake, several boreholes of different depths were drilled. Those boreholes penetrated the fault plane. The physical (mechanical, thermal, hydraulic, electric, and magnetic) parameters were measured either on the core samples or through well-loggings. Results are significant for studies of the Chelungpu fault. However, the measured results are published in different articles and reports. It is not convenient for the earth scientists to take advantage of those results. Hence, those results are compiled and described in this paper. In addition, the correlations among a few parameters are also reported. 2010 English 10170839 10.3319/TAO.2009.09.01.01(T) Terrestrial, Atmospheric and Oceanic Sciences 21 655-673 Institute of Earth Sciences, Academia Sinica, Taipei 115, Taiwan 4 borehole; Chi-Chi earthquake 1999; earthquake magnitude; fault plane; physical property; rupture; well logging, Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-77956575983&doi=10.3319%2fTAO.2009.09.01.01%28T%29&partnerID=40&md5=b9fc2de6651f7daaa38ac52b008a0429 cited By 4 J.-H. Wang article Lin201082 To reveal details of stress perturbations associated with faults and fractures, we investigated the faults and large fractures accompanied by stress-induced borehole breakouts or drilling-induced tensile fractures in hole B of the Taiwan Chelungpu-fault Drilling Project (TCDP). Then, we determined the relationship between the faults and fractures and stress orientation changes. We identified faults and fractures from electrical images of the borehole wall obtained by downhole logging but also from photographs and descriptions of retrieved core samples, and measured the variations in the principal horizontal stress orientation ascertained from borehole breakouts observed on the electrical images in the vicinity of the faults and fractures. Identification of geological structures (faults, fractures, and lithologic boundaries) by electrical images only is difficult and may sometimes yield incorrect results. In a novel approach, therefore, we used both the electrical images and core photographs to identify geological structures. We found four patterns of stress orientation change, or no change, in the vicinity of faults and fractures in TCDP hole B: (i) abrupt (discontinuous) rotation in the vicinity of faults or fractures; (ii) gradual rotation; (iii) suppression of breakouts at faults, fractures, or lithologic boundaries; and (iv) no change in the stress orientation. We recognized stress fluctuations, that is, heterogeneous mesoscale (≥ 10 cm) stress distributions with respect to both stress orientation and magnitude. In addition, we found that stress state changes occurred frequently in the vicinity of faults, fractures, and lithologic boundaries. © 2009 Elsevier B.V. All rights reserved. 2010 English 00401951 10.1016/j.tecto.2009.06.020 Tectonophysics 482 82-91 Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, 200 Monobe-otsu, Nankoku, Kochi, 783-8502, Japan; Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, Japan; Institute of Geophysics, National Central University, Chung-Li, 32054, Taiwan; Department of Materials Science and Engineering, the Geological Engineering Program, University of Wisconsin, Madison, WI 53706, United States; Graduate School of Science, Osaka University, Osaka, 560-0043, Japan 1-4 Borehole wall; Downholes; Drilling projects; Drilling-induced tensile fractures; Electrical images; Fracture stress; Geological structures; Horizontal stress; Mesoscale; Principal stress; Stress distribution; Stress fluctuations; Stress orientations; Stress perturbations; Stress state; Stress-induced, Drilling; Fracture; Photography; Rotation; Stress concentration, Boreholes, borehole breakout; core analysis; drilling; electrical method; fault; fracture; image analysis; spatial variation; stress analysis; stress field; tensile stress, Chelungpu Fault Zone; Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-76049112276&doi=10.1016%2fj.tecto.2009.06.020&partnerID=40&md5=35a54b66f2a8f85269af20fac0e88d9a cited By 67 W. Lin E.-C. Yeh J.-H. Hung B. Haimson T. Hirono article Haimson201065 The paper describes the computation of the maximum horizontal stress (σH) magnitude in the vicinity of the Chelungpu Fault, Taiwan, host of the slip zone during the Chi-Chi earthquake (Mw 7.6; 1999). The scientific hole B intercepts the Chelungpu Fault at 1136 m. At the depths of logged breakouts (940-1310 m), the vertical stress (σv) as estimated from density logs increases linearly with depth from 22 to 31 MPa. A series of leak-off tests yielded two reliable shut-in pressures, 23.7 MPa at 1085 m and 29.8 MPa at 1279 m, which are lower than the estimated σv, albeit by only 2.1 and 0.6 MPa, respectively. In our analysis the shut-in pressures were considered to represent estimates of the least horizontal principal stresses (σh) at the respective depths, and consequently the test-induced fractures were assumed to have been vertical. Principal stress directions had been previously determined by others (105°-155° for the maximum horizontal stress, σH, except in the immediate vicinity of the Chelungpu Fault). The contribution of this paper is the estimation of the σH magnitude by considering that the state of stress at the points of intersection between breakout and borehole wall is in a state of limit equilibrium with the true triaxial strength criterion. The resulting σH in the range of logged breakouts increases with depth from 55 MPa at 940 m to 59 MPa at 1310 m. Thus, the estimated state of stress prevailing across the Chelungpu Fault is compatible with strike-slip, but marginally also with thrust faulting. However, the likelihood that the shut-in pressures actually represent σv magnitudes, and that the leak-off test-induced fractures were sub-horizontal, cannot be ignored. In that case the state of stress would clearly favor thrust faulting. © 2009 Elsevier B.V. All rights reserved. 2010 English 00401951 10.1016/j.tecto.2009.05.016 Tectonophysics 482 65-72 Department of Materials Science and Engineering, the Geological Engineering Program, University of Wisconsin, 1609 University Avenue, Madison, WI 53706, United States; Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, 200 Monobe-otsu, Nankoku, Kochi, 783-8502, Japan; Institute of Geophysics, National Central University, Jhongli, Taiwan; Department of Geoscience, National Taiwan University, Taipei, Taiwan 1-4 Borehole wall; ChiChi earthquake; Density log; Estimated state; Horizontal stress; Insitu stress; Leak-off tests; Limit equilibrium; Principal stress; Shut-in pressure; Slip zones; State of stress; Strength criteria; Thrust faulting; True triaxial strength; True triaxial strength criteria; Vertical stress, Asphalt pavements; Blowouts; Electromagnetic logging; Fracture; Instruments; Maximum likelihood estimation; Radioactivity logging; Stress measurement, Boreholes, borehole breakout; fault zone; in situ stress; integrated approach; pressure effect; stress analysis; strike-slip fault; thrust fault; triaxial test; well logging, Chelungpu Fault Zone; Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-76049106322&doi=10.1016%2fj.tecto.2009.05.016&partnerID=40&md5=7ac5416ff38f9f006d05723c15e86631 cited By 41 B. Haimson W. Lin H. Oku J.-H. Hung S.-R. Song article Zhang2010295 The in-situ stress computations presented by Haimson et al. (2010) overestimated the maximum horizontal stress in the vicinity of the Chelungpu Fault, Taiwan. Our analyses from extended leak-off tests, drilling-induced tensile fractures, and Anderson's faulting theory show considerable lower values for the maximum horizontal stress. Our results suggest that closer to the ruptured fault, more SH is released, implying a strong earth crest in the shallower section, which is far away from the ruptured fault. However, it would require more detailed and intensive work in order to achieve an accurate interpretation of the in-situ stress in this region. © 2010 Elsevier B.V. 2010 English 00401951 10.1016/j.tecto.2010.04.038 Tectonophysics 492 295-298 Shell Exploration and Production Company, Houston, TX 77079, United States; The University of Oklahoma, Norman, OK 73019, United States 1-4 https://www.scopus.com/inward/record.uri?eid=2-s2.0-78650521863&doi=10.1016%2fj.tecto.2010.04.038&partnerID=40&md5=6f262b57bb991c651a40d87242050cc0 cited By 26 J. Zhang J.-C. Roegiers article Otsuki200913 The seismic slip behavior during the 1999 Chi-Chi, Taiwan, earthquake (Mw 7.6) was contrastive between the northern and southern segments of the activated Chelungpu fault; large, fast and smooth slips with large stress drop in the north, while smaller, slower and irregular slips with smaller stress drop in the south. We analyzed the pseudotachylyte samples recovered from 1194 m, 1243 m and 1314 m depths of Hole-B of Taiwan Chelungpu fault Drilling Project (TCDP) to reveal the spatial difference in friction mechanism. All pseudotachylyte layers are thin (0.7-2.8 cm), the volume fraction of protoliths is very large (more than 63%), and the estimated temperature distribution is very heterogeneous from ca. 750-1750 °C. These observations suggest that these pseudotachylyte melts were in the partial melting regime of Montgomery [Montgomery, R.S., 1976. Friction and wear at high sliding speeds. Wear 36, 275-298] where friction coefficient is abnormally large. Similar pseudotachylyte was found already in the core sample from 175 m depth of the Nanto borehole penetrating the southern fault. Since both pseudotachylyte samples from the two boreholes are older than the 1999 Chi-Chi event and have been uplifted from depths farther down-dip of their current locations, it is likely that recent seismic ruptures also would have encountered these mechanical barriers of viscous melt patches at deeper parts in the north than in the south. Elastohydrodynamic lubrication of clayey gouge worked effectively at the shallower parts of the northern segment, however there is no evidence that it played an important role in the south. These differences are the plausible causes of the contrastive local slip behaviors during the Chi-Chi earthquake. © 2008 Elsevier B.V. All rights reserved. 2009 English 00401951 10.1016/j.tecto.2009.01.008 Tectonophysics 469 13-24 Department of Geology, Graduate School of Science, Tohoku University, Sendai, Japan; Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka, Japan; Marine Works Japan, Nankoku, Japan; Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, Nankoku, Japan; Department of Geoscience, National Taiwan University, Taipei, Taiwan 1-4 Chelungpu fault; Chi-Chi earthquake; Partial melting; Pseudotachylyte; Seismic slip, Boreholes; Drops; Elastohydrodynamic lubrication; Friction; Melting; Tribology, Earthquakes, active fault; Chi-Chi earthquake 1999; earthquake magnitude; earthquake rupture; fault gouge; fault slip; focal mechanism; partial melting; pseudotachylite; uplift https://www.scopus.com/inward/record.uri?eid=2-s2.0-63049105877&doi=10.1016%2fj.tecto.2009.01.008&partnerID=40&md5=0c3c2d3b8a5f902fbf447f4d5f854729 cited By 21 K. Otsuki T. Hirono M. Omori M. Sakaguchi W. Tanigawa W. Lin W. Soh S.-S. Rong article Kuo2009 The Taiwan Chelungpu-fault Drilling Project (TCDP) Hole-A recovered continuous core samples across the rupture zone of the 1999 Chi-Chi earthquake (Mw7.6). Studying in-situ chemical properties sequentially from fresh-fault-zone materials of the Chelungpu fault provides insight into possible faulting mechanisms. Distinct anomalies of mineral assemblages at the 1111-m fault zone of TCDP Hole-A are found to be: (1) A decrease in clay content within the primary slip zone (PSZ); and (2) A significant decline of illite, disappearance of chlorite and kaolinite, and spike in smectite within the PSZ. Meanwhile, features relating to melting or amorphous material in the PSZ have been observed by SEM and TEM. The results suggest that the PSZ might have experienced generation of glassy materials such as pseudotachylyte by the expense of clay minerals due to strong shear heating, then prompt alteration of pseudotachylyte into smectite. Characteristics of clay minerals and images obtained from electronic microscopes in the PSZ thus imply that pseudotachylyte possibly developed during the 1999 Chi-Chi earthquake, but quickly altered into smectite. This particular phenomenon may explain why pseudotachylyte is rarely found in exhumed hydrated fault zones. Copyright 2009 by the American Geophysical Union. 2009 English 00948276 10.1029/2009GL039269 Geophysical Research Letters 36 American Geophysical Union Department of Geosciences, National Taiwan University, No. 1, Roosevelt Road, Taipei 10617, Taiwan; Intemational Laboratory ADEPT France-Taiwan, CNRS, NSC, Taipei, Taiwan; Department of Earth Sciences, National Taiwan Normal University, Taipei, Taiwan; Institute of Applied Geosciences, National Taiwan Ocean University, 2 Pei-Ning Road, Keelung 20224, Taiwan 18 Amorphous materials; Chemical properties; Clay alteration; Earthquakes; Hydrates; Kaolinite; Silicate minerals, ChiChi earthquake; Clay content; Drilling projects; Electronic microscopes; Fault zone; Glassy materials; In-situ; Mineral assemblage; Pseudotachylytes; Rupture zone; SEM and TEM; Shear heating; Slip zones; Smectites, Minerals, amorphous medium; chemical property; Chi-Chi earthquake 1999; clay mineral; earthquake magnitude; earthquake rupture; fault zone; faulting; pseudotachylite; seismic zone; smectite, Asia; Chelungpu Fault Zone; Eurasia; Far East; Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-72149098406&doi=10.1029%2f2009GL039269&partnerID=40&md5=ea7ce88083b82e7884083c314c6c03a6 cited By 77 L.-W. Kuo S.-R. Song E.-C. Yeh H.-F. Chen article Tanikawa2009 We carried out low- and high-velocity friction tests on fault rock samples from shallow boreholes on the Taiwan Chelungpu fault and measured their fluid transport properties under high pressure, with the objective of explaining the different seismic behaviors in the northern and southern sections of the fault during the 1999 Chi-Chi earthquake. Our results of low-velocity friction tests demonstrate that fault gouge from the southern section of the fault exhibits velocity-weakening frictional behavior, whereas gouge from the northern section exhibits velocity-strengthening friction. Friction in the northern gouge decreased strongly with increasing wetness, whereas friction in southern gouge samples was not affected by wetness. A rapid reduction of friction was observed immediately after the onset of slip in high-velocity friction tests. The results of high-velocity friction tests were similar for all fault gouge samples tested, although permeability in the northern fault zone was lower than that in the south. Numerical modeling indicated that thermal pressurization in the northern fault zone promoted stress reduction and fault instability during slip, whereas it did not in the south. This contrasting seismic behavior between north and south is caused mainly by differences in fluid transport properties of the slip zones. More efficient thermal pressurization in the north explains the large slip displacement there. The results of our low-velocity friction tests are consistent with nucleation of the Chi-Chi earthquake in the south and propagation of the rupture from south to north. Copyright 2009 by the American Geophysical Union. 2009 English 21699313 10.1029/2008JB005750 Journal of Geophysical Research: Solid Earth 114 Blackwell Publishing Ltd Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, 200 Monobe-otsu, Nankoku, Kochi 783-8502, Japan; Department of Earth and Planetary Systems Science, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan 1 borehole; Chi-Chi earthquake 1999; earthquake rupture; fault zone; fluid flow; friction; high pressure; numerical model; seismicity; slip, Asia; Chelungpu Fault Zone; Eurasia; Far East; Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-63049098820&doi=10.1029%2f2008JB005750&partnerID=40&md5=deec537dc06f6a9c313d3cf7c2b1cbac cited By 60 W. Tanikawa T. Shimamoto article Hung2009307 Continuous cores and a suit of geophysical measurements were collected in two scientific drill holes to understand physical mechanisms involved in the large displacements during the 1999 Chi-Chi earthquake. Physical properties obtained from wire-line logs including P- and S-wave sonic velocity, gamma ray, electrical resistivity, density and temperature, are primarily dependent on parameters such as lithology, depth and fault zones. The average dip of bedding, identified from both cores and FMI (or FMS) logs, is about 30° towards SE. Nevertheless, local azimuthal variations and increasing or decreasing bedding dips appear across fault zones. A prominent increase of structural dip to 60°-80° below 1856 m could be due to deformation associated with propagation of the Sanyi fault. A total of 12 fault zones identified in hole-A are located in the Plio-Pleistocene Cholan Formation, Pliocene Chinshui Shale and Miocene Kueichulin Formation. The shallowest fault zone occurs at 1111 m depth (FZ1111). It is a 1 m gouge zone including 12 cm of thick indurate black material. We interpreted this zone as the slip zone during Chi-Chi earthquake. FZ1111 is characterized by: 1) bedding-parallel thrust fault with 30-degree dip; 2) the lowest resistivity; 3) low density, Vp and Vs, 4) high Vp/Vs ratio and Poisson's ratio; 5) low energy and velocity anisotropy, and low permeability within the homogeneous 1 m gouge zone; 6) increasing gas (CO2 and CH4) emissions, and 7) appearance of smectite within the primary slip zone. In situ stresses at the drill site were inferred from leak-off tests, borehole breakouts and drilling-induced tensile fractures from borehole FMS/FMI logs, and shear seismic wave anisotropy from DSI logs. The dominant fast shear-wave polarization direction is in good agreement with regional maximum horizontal stress axis, particularly within the strongly anisotropic Kueichulin Formation. A conjugate set of secondary directions are parallel to microcrack orientations. A drastic change of orientation of fast shear-wave polarization across the Sanyi thrust fault at the depth of 1712 m reflects the change of stratigraphy, physical properties and structural geometry. © 2007 Elsevier B.V. All rights reserved. 2009 English 00401951 10.1016/j.tecto.2007.11.014 Tectonophysics 466 307-321 Institute of Geophysics, National Central University, Jhongli, Taiwan; Center for Deep Earth Exploration, Japan Agency for Marine-Earth Science and Technology, Japan; Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, Japan 3-4 Azimuthal variations; Black materials; Chi-Chi earthquake; Drill holes; Drill sites; Drilling-induced tensile fractures; Electrical resistivities; Fault zones; Fault-zone properties; Gamma-ray; Geophysical measurements; Horizontal stress; In-situ stress; Large displacements; Leak-off tests; Low densities; Low energies; Low permeabilities; Micro cracks; Miocene; Physical mechanisms; Plio-pleistocene; Pliocene; Poisson's ratios; S-wave anisotropy; Slip zones; Smectite; Sonic velocities; Stress state; Structural geometries; Subsurface structures; Taiwan Chelungpu Fault Drilling Project; Thrust faults; Velocity anisotropies; Wave polarizations, Anisotropy; Clay minerals; Drilling; Earthquakes; Electric resistance; Gamma rays; Lithology; Poisson ratio; Polarization; Rock drills; Seismic waves; Shear waves; Stratigraphy; Structural geology; Thermal logging; Viscosity measurement; Waves, Boreholes, borehole breakout; Chi-Chi earthquake 1999; deformation; drilling; fault geometry; fault propagation; fault zone; in situ stress; lithology; Miocene; P-wave; physical property; Pleistocene; Pliocene; S-wave; seismic anisotropy; wave velocity https://www.scopus.com/inward/record.uri?eid=2-s2.0-60649107827&doi=10.1016%2fj.tecto.2007.11.014&partnerID=40&md5=472cf8a3aba0ba3af43d3351aaff7ff7 cited By 52 J.-H. Hung K.-F. Ma C.-Y. Wang H. Ito W. Lin E.-C. Yeh article Wu2008949 Taiwan Chelungpu-fault Drilling Project (TCDP) was initiated to understand the physical mechanisms involved in the large displacements of the 1999 Taiwan Chi-Chi earthquake. Continuous measurements of cores (including laboratory work) and a suite of geophysical downhole logs, including P- and S-wave sonic velocity, gamma ray, electrical resistivity, density, temperature, electrical borehole images and dipole-shear sonic imager, were acquired in Hole-A over the depth of 500-2003 m. Integrated studies of cores and logs facilitate qualitative and quantitative comparison of subsurface structures and physical properties of rocks. A total of 10 subunits were divided on the basis of geophysical characteristics. Generally, formation velocity and temperature increase with depth as a result of the overburden and thermal gradient, respectively. Gamma ray, resistivity, formation density, shear velocity anisotropy and density-derived porosity are primarily dependent on the lithology. Zones with changes of percentage of shear wave anisotropy and the fast shear polarization azimuth deduced from Dipole Shear-Imager (DSI) are associated with the appearance of fractures, steep bedding and shear zones. The fast shear wave azimuth is in good agreement with overall dip of the bedding (approximately 30° towards SE) and maximum horizontal compressional direction, particularly in the Kueichulin Formation showing strong shear wave velocity anisotropy. Bedding-parallel fractures are prevalent within cores, whereas minor sets of high-angle, NNW-SSE trending with N- and S-dipping fractures are sporadically distributed. The fault zone at depth 1111 m (FZA1111) is the Chi-Chi earthquake slip zone and could be a fluid conduit after the earthquake. The drastic change in fast shear wave polarization direction across the underlying, non-active Sanyi thrust at depth 1710 m reflects changes in stratigraphy, physical properties and structural geometry. © 2008 The Authors Journal compilation © 2008 RAS. 2008 English 0956540X 10.1111/j.1365-246X.2008.03841.x Geophysical Journal International 174 949-965 Institute of Geophysics, National Central University, Taiwan; Department of Geosciences, National Taiwan University, Taiwan; Institute of Applied Geology, National Central University, Taiwan 3 azimuth; Chi-Chi earthquake 1999; displacement; earthquake mechanism; fault zone; S-wave; seismic anisotropy; seismicity; shear zone, Asia; Eurasia; Far East; Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-50649086610&doi=10.1111%2fj.1365-246X.2008.03841.x&partnerID=40&md5=51c01868c82cd8c7181b65928414feea cited By 22 Y.-H. Wu E.-C. Yeh J.-J. Dong L.-W. Kuo J.-Y. Hsu J.-H. Hung article Ishikawa2008679 Aqueous fluids are thought to have an essential role in faulting and the dynamic propagation of earthquake rupture. Fluid overpressure can affect earthquake nucleation and in a process termed thermal pressurization, pore fluid pressure produced by frictional heating can reduce the effective normal stress acting on the fault surface. This may lead to a marked reduction in fault strength during slip. However, the coseismic presence of fluids within slip zones and the role of fluids in dynamic fault weakening is still a matter of debate. Here we present compositions of major and trace elements as well as isotope ratios of core samples representing relatively undamaged as well as very fine-grained deformed material from three active zones of the Chelungpu fault, Taiwan. Depth profiles across the most intensely sheared bands that range in thickness from 2-15 cm exhibit sharp compositional peaks of fluid-mobile elements and of strontium isotopes. We suggest that high-temperature fluids (>350 C) derived from heating of sediment pore fluids during the earthquake interacted with material within the fault zone and mobilized the elements. The coseismic presence of high-temperature fluids under conditions of low hydraulic diffusivity within the fault zone is favourable for thermal pressurization. This effect may have caused a dynamic decrease of friction along the Chelungpu fault during the 1999 magnitude 7.6 Chi-Chi earthquake. © 2008 Macmillan Publishers Limited. 2008 English 17520894 10.1038/ngeo308 Nature Geoscience 1 Nature Publishing Group 679-683 Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 200 Monobe-otsu, Nankoku, Kochi 783-8502, Japan; Marine Works Japan Ltd., Nankoku, Kochi 783-8502, Japan; Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan; Research Center for Inland Seas, Kobe University, Kobe, Hyogo 657-8501, Japan; Department of Geosciences, National Taiwan University, Taipei 10617, Taiwan 10 https://www.scopus.com/inward/record.uri?eid=2-s2.0-62749157721&doi=10.1038%2fngeo308&partnerID=40&md5=effd7f30c5fe23b2cde68abed283f104 cited By 105 T. Ishikawa M. Tanimizu K. Nagaishi J. Matsuoka O. Tadai M. Sakaguchi T. Hirono T. Mishima W. Tanikawa W. Lin H. Kikuta W. Soh S.-R. Song article Hirono2007 The Taiwan Chelungpu-Fault Drilling Project was undertaken in 2002 to investigate the faulting mechanism of the 1999 Mw 7.6 Taiwan Chi-Chi earthquake. Hole B penetrated the Chelungpu fault, and core samples were recovered from between 948.42- and 1352.60-m depth. Three major zones, designated FZB1136 (fault zone at 1136-m depth in hole B), FZB1194, and FZB1243, were recognized in the core samples as active fault zones within the Chelungpu fault. Nondestructive continuous physical property measurements, conducted on all core samples, revealed that the three major fault zones were characterized by low gamma ray attenuation (GRA) densities and high magnetic susceptibilities. Extensive fracturing and cracks within the fault zones and/or loss of atoms with high atomic number, but not a measurement artifact, might have caused the low GRA densities, whereas the high magnetic susceptibility values might have resulted from the formation of magnetic minerals from paramagnetic minerals by frictional heating. Minor fault zones were characterized by low GRA densities and no change in magnetic susceptibility, and the latter may indicate that these minor zones experienced relatively low frictional heating. Magnetic susceptibility in a fault zone may be key to the determination that frictional heating occurred during an earthquake on the fault. Copyright 2007 by the American Geophysical Union. 2007 English 21699313 10.1029/2006JB004738 Journal of Geophysical Research: Solid Earth 112 Blackwell Publishing Ltd Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka 560-0043 Osaka, Japan; Kochi Institute for Core Sample Research, Japan Agency for Marine Earth Science and Technology, Nankoku, Kochi, Japan; Department of Geosciences, National Taiwan University, Taipei, Taiwan; Department of Geophysics, School of Earth Sciences, Stanford University, Stanford, CA, United States; Center for Advanced Marine Core Research, Kochi University, Nankoku, Kochi, Japan; Department of Natural Environmental Science, Faculty of Science, Kochi University, Kochi, Japan; Institute for Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan; Center for Deep Earth Exploration, Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan; Institute for Research on Earth Evolution, Japan Agency for Marine Earth Science and Technology, Yokosuka, Japan; Institute of Geophysics, National Central University, Jhongli, Taiwan; Marine Works Japan Ltd., Yokohama, Japan 7 active fault; Chi-Chi earthquake 1999; fault zone; faulting; magnetic susceptibility, Asia; Eurasia; Far East; Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-34548522847&doi=10.1029%2f2006JB004738&partnerID=40&md5=739cc0d49cf2d2f767a9aac8c6da03a4 cited By 42 T. Hirono E.-C. Yeh W. Lin H. Sone T. Mishima W. Soh Y. Hashimoto O. Matsubayashi K. Aoike H. Ito M. Kinoshita M. Murayama S.-R. Song K.-F. Ma J.-H. Hung C.-Y. Wang Y.-B. Tsai T. Kondo M. Nishimura S. Moriya T. Tanaka T. Fujiki L. Maeda H. Muraki T. Kuramoto K. Sugiyama T. Sugawara article Hung200755 2007 English 18168957 10.2204/iodp.sd.s01.27.2007 Scientific Drilling 55-58 Department of Earth Sciences and Institute of Geophysics, National Central University, No. 300, Jhongda Road, Johngli City, Taoyuan County, 32001, Taiwan; Department of Earth Sciences and Institute of Geophysics, National Central University, No. 300, Jhongda Road, Johngli City, Taoyuan County, 32001, Taiwan; Department of Geosciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, 10617, Taiwan; Center for Deep Earth Exploration (CDEX), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), 3173-25 Showa-machi, Kanazawa-ku, Yokohama, Kanagawa 236-0001, Japan; Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), B200 Monobe, Nankoku, Kochi, 783-8502, Japan 1 SUPPL. 1 https://www.scopus.com/inward/record.uri?eid=2-s2.0-78651537907&doi=10.2204%2fiodp.sd.s01.27.2007&partnerID=40&md5=cf701d4721308fc9bf5ed142f7be4a5d cited By 2 J.-H. Hung K.-F. Ma C.-Y. Wang S.-R. Song H. Ito W. Lin E.-C. Yeh article Wu2007 The Taiwan Chelungpu-fault Drilling Project (TCDP) drilled a 2-km-deep research borehole to investigate the structure and mechanics of the Chelungpu Fault that ruptured in the 1999 Mw 7.6 Chi-Chi earthquake. Geophysical logs of the TCDP were carried out over depths of 500-1900 in, including Dipole Sonic Imager (DSI) logs and Formation Micro Imager (FMI) logs in order to identify bedding planes, fractures and shear zones. From the continuous core obtained from the borehole, a shear zone at a depth of 1110 meters is interpreted to be the Chelungpu fault, located within the Chinshui Shale, which extends from 1013 to 1300 meters depth. Stress-induced borehole breakouts were observed over nearly the entire length of the wellbore. These data show an overall stress direction (∼N115°E) that is essentially parallel to the regional stress field and parallel to the convergence direction of the Philippine Sea plate with respect to the Eurasian plate. Variability in the average stress direction is seen at various depths. In particular there is a major stress orientation anomaly in the vicinity of the Chelungpu fault. Abrupt stress rotations at depths of 1000 in and 1310 in are close to the Chinshui Shale's upper and lower boundaries, suggesting the possibility that bedding plane slip occurred during the Chi-Chi earthquake. Copyright 2007 by the American Geophysical Union. 2007 English 00948276 10.1029/2006GL028050 Geophysical Research Letters 34 Institute of Geophysics, National Central University, 300 Jhongda Road, Chung-Li 32001, Taiwan; Department of Geophysics, Stanford University, Stanford, CA 94305, United States; Japan Agency for Marine-Earth Science and Technology, 2-9 Nishi-Shinbashi 1-chome, Minato-ku, Tokyo 105-0003, Japan; U.S. Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025, United States 1 Boreholes; Earthquakes; Image sensors; Mechanics; Structural geology; Tectonics, Dipole Sonic Imager (DSI); Formation Micro Imager (FMI); Geophysical logs, Geophysical prospecting, bedding plane; borehole; Chi-Chi earthquake 1999; earthquake rupture; Eurasian plate; Philippine Sea plate; shear zone; stress field; well logging, Asia; Eurasia; Far East; Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-34548007902&doi=10.1029%2f2006GL028050&partnerID=40&md5=fc41a04af36a0475f6b888f2d1f3587f cited By 82 H.-Y. Wu K.-F. Ma M. Zoback N. Boness H. Ito J.-H. Hung S. Hickman book Reches2007235 Drilling into active faults has become a major scientific endeavor during the last decade and it appears as a most promising approach to resolve long-standing questions in earthquake and faulting processes. The first boreholes were drilled into the Nojima Fault following the 1995 Kobe earthquake. Since then, drilling into active faults has begun or been planned in a wide range of tectonic settings, such as a strike-slip plate boundary (San Andreas Fault, California), a thrust zone in an active orogenic belt (Chelungpu Fault, Taiwan), a normal fault in an active rift zone (Aigion Fault, Greece), a reactivated Archean fault (Pretorius Fault, South Africa), and a major subduction thrust (Nankai Thrust, Japan). These projects have already revealed many details on in-situ stresses, fault-zone structure, fault-rock composition, mechanical properties, heat flow, and near-field seismicity. Furthermore, most of these projects will continue to serve as observatories for monitoring fault deformation, fluid pressure and near-field earthquake source processes for a decade or two. Future drilling projects will focus on near-field observations and long-term monitoring of time-dependent processes and in-situ experimentation in active fault zones. Collaboration with industry and government will address practical issues pertaining to petroleum and geothermal energy, radioactive waste disposal, and urban seismic hazards. The outcome of these international efforts in drilling active faults will revolutionize our understanding of the processes controlling faulting and earthquakes and lead to a stronger scientific basis for earthquake hazard mitigation. © 2007 Springer-Verlag Berlin Heidelberg. 2007 English 9783540687771 10.1007/978-3-540-68778-8_6 Continental Scientific Drilling: A Decade of Progress, and Challenges for the Future Springer Berlin Heidelberg 235-258 School of Geology and Geophysics, University of Oklahoma, Norman, OK 73019, United States; Center for Deep Earth Exploration, Japan Agency for Marine-Earth Science and Technology, Yokohama, Kanagawa 236-0001, Japan https://www.scopus.com/inward/record.uri?eid=2-s2.0-58749095781&doi=10.1007%2f978-3-540-68778-8_6&partnerID=40&md5=2970d8913c96830d31b3214ee317af9a cited By 13 Z. Reches H. Ito article Lin2007379 In order to understand the feature of rock stress change at different depths above, within, and beneath the Chelungpu fault after the Chi-Chi earthquake, we employed a core-based stress measurement method, anelastic strain recovery (ASR) technique to determine both the orientations and magnitudes of present three-dimensional principal rock stresses using drill core samples retrieved from Taiwan Chelungpu-fault Drilling Project (TCDP) main Hole-A. The core samples used were taken from three depths; and their lithology were sandstone at depths of 592 and 1755 m and siltstone at 1112 m. The anelastic strains of the specimens in nine directions, including six independent directions, were measured after its in-situ stress was released. Acquired anelastic strains were of high quality and reached several hundred microstrains, which is sufficiently high for the accuracy of the measurement system used. Thus, the strain data could be used for three-dimensional analysis resulting in the determination of orientations and the estimation of magnitudes of the principal in-situ stresses. Preliminary stress measurement results showed that the orientations of principal stresses changed between the shallower depth above the fault and the deeper depth beneath it, that is, the present stress distribution in the TCDP hole might be influenced by the Chelungpu fault rupture. At the same time, anelastic strain recovery measurement is well suited for the task of directly determining the orientations of principal in-situ stresses and to estimate the magnitude of stresses at large/great depth. 2007 English 10170839 10.3319/TAO.2007.18.2.379(TCDP) Terrestrial, Atmospheric and Oceanic Sciences 18 379-393 Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, Kochi, Japan; Center for Deep Earth Exploration, Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan; Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka, Japan; Department of Earth Sciences, Institute of Geophysics, National Central University, Chung-Li, Taiwan; Department of Geosciences, National Taiwan University, Taipei, Taiwan 2 anelasticity; borehole; Chi-Chi earthquake 1999; core analysis; drilling; fault zone; in situ measurement; siltstone; strain; stress measurement; three-dimensional modeling https://www.scopus.com/inward/record.uri?eid=2-s2.0-34547587461&doi=10.3319%2fTAO.2007.18.2.379%28TCDP%29&partnerID=40&md5=e69ec227e125175a3a91bc311b317cd1 cited By 37 W. Lin E.-C. Yeh H. Ito T. Hirono W. Soh C.-Y. Wang K.-F. Ma J.-H. Hung S.-R. Song article Song2007 2007 English 10170839 10.3319/TAO.2007.18.2.I(TCDP) Terrestrial, Atmospheric and Oceanic Sciences 18 I-VI Department of Geosciences, National Taiwan University, Taipei, Taiwan; Department of Earth Sciences, Institute of Geophysics, National Central University, Chung-Li, Taiwan 2 https://www.scopus.com/inward/record.uri?eid=2-s2.0-34547556308&doi=10.3319%2fTAO.2007.18.2.I%28TCDP%29&partnerID=40&md5=27c03ab0708b35fe2aacffbff2872ee8 cited By 12 S.-R. Song C.-Y. Wang J.-H. Hung K.-F. Ma article Yeh2007327 Taiwan Chelungpu-fault Drilling Project was conducted in drill site Dakeng, Taichung City of central western Taiwan during 2004 - 2005 principally to investigate the rupture mechanism in the northern segment of the Chi-Chi earthquake of 21 September 1999, and also to examine regional stratigraphy and tectonics. Core examination (500 - 1800 m) of Hole-A gave profound results aiding in illustrating the lithologic column, deformation structure, and architectural pattern of fault zones along the borehole. Lithology column of Hole-A was identified downward as the Cholan Formation (500 - 1027 m), Chinshui Shale (1027 - 1268 m), Kueichulin Formation (1268 - 1712 m), and back to the Cholan Formation (1712 - 2003 m) again. A dramatic change is observed regarding sedimentation age and deformation structure around 1712 m. Along the core, most bedding dips 30° toward N105°. Around 1785 m, bedding dip jumps up to 70° until the bottom of borehole. Five structure groups of different orientations (dip direction/dip) are observed throughout the core. Based on the orientation and sense of shear, they are categorized as thrust (105/30), left-lateral fault (015/30 - 80), right-lateral fault (195/30 - 80), normal fault (105/5 - 10), and backthrust (285/40 - 50). Ten fault zones have been recognized between 500 and 2003 m. We interpret the fault zone located at around 1111 m as being the most likely candidate for rupture deformation during Chi-Chi earthquake. The fault zone seated around 1712 m is recognized as the Sanyi fault zone which is 600 m beneath the Chelungpu fault zone. Ten fault zones including thrust faults, strike-slip faults and backthrust are classified as the Chelungpu Fault System (<1250 m) and the Sanyi Fault System (>1500 m). According to the deformation textures within fault zones, the fault zones can be categorized as three types of deformation: distinct fracture deformation, clayey-gouge deformation, and soft-rock deformation. Fracture deformation is dominant within the Chelungpu Fault System and abother two architectures prevail in the Sanyi Fault System. The fracture deformation pattern is asymmetric, which depended the shear sense of fault zone. From the core examination of TCDP Hole-A, the lithology plays an important role in controlling the location and deformation of fault zones. 2007 English 10170839 10.3319/TAO.2007.18.2.327(TCDP) Terrestrial, Atmospheric and Oceanic Sciences 18 327-357 Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, Kochi, Japan; Department of Geology and Mineralogy, Kyoto University, Kyoto, Japan; Department of Natural Environmental Science, Kochi University, Kochi, Japan; Department of Earth Sciences, Institute of Geophysics, National Central University, Chung-Li, Taiwan; Department of Geosciences, National Taiwan University, Taipei, Taiwan 2 Chi-Chi earthquake 1999; core analysis; deformation mechanism; drilling; fault zone; lithology; normal fault; rupture; tectonic structure, Asia; Eurasia; Far East; Taichung; Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-34547564684&doi=10.3319%2fTAO.2007.18.2.327%28TCDP%29&partnerID=40&md5=805bc91922c2373865b0c64a8e26f672 cited By 56 E.-C. Yeh H. Sone T. Nakaya K.-H. Ian S.-R. Song J.-H. Hung W. Lin T. Hirono C.-Y. Wang K.-F. Ma W. Soh M. Kinoshita article Sone2007359 Structural characteristics of fault rocks distributed within major fault zones provide basic information in understanding the physical aspects of faulting. Mesoscopic structural observations of the drilled cores from Taiwan Chelungpu-fault Drilling Project Hole-A are reported in this article to describe and reveal the distribution of fault rocks within the Chelungpu Fault System. The Chelungpu Fault System in Hole-A was encountered at a depth of between 1050 - 1250 m where deformation structures increased. Three major fault zone structures were found at approximate depths of 1111, 1153, and 1221 m. The presence of wide fault rock regions were mostly concentrated in these 3 fault zones. The fault zone at 1111 m mainly consists of a nearly brecciated fracture zone and a clayey fault gouge zone of about 1.05 m in thickness. Fault rocks from the fault zone at 1153 m are characterized by the presence of sand grains in the matrix content, consisting of a 1.1-m thick fault breccia zone and a 0.35-m thick fault gouge zone. The fault zone at 1221 m consists of fault breccia and fault gouge of 1.15 m in total thickness. These are relatively harder and darker in color than the previous 2 fault zones. Each of the 3 fault zones contains a few layers of dark colored rocks of approximately 5 - 80 mm in thickness within the fault breccia and fault gouge zones. These dark colored rocks were found distinctively within the fault rocks. However, there relation to the process of faulting is not clearly understood and shall be discussed in detail with the aid of microscopic observations. 2007 English 10170839 10.3319/TAO.2007.18.2.359(TCDP) Terrestrial, Atmospheric and Oceanic Sciences 18 359-377 Department of Geology and Mineralogy, Kyoto University, Kyoto, Japan; Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, Kochi, Japan; Department of Natural Environmental Science, Kochi University, Kochi, Japan; Department of Earth Sciences, Institute of Geophysics, National Central University, Chung-Li, Taiwan; Department of Geosciences, National Taiwan University, Taipei, Taiwan; Department of Geophysics, Stanford University, Stanford, CA, United States 2 borehole; breccia; core analysis; deformation mechanism; drilling; fault gouge; fault zone; fracture zone, Asia; Eurasia; Far East; Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-34547578502&doi=10.3319%2fTAO.2007.18.2.359%28TCDP%29&partnerID=40&md5=3f8ad13a455eb7c097fa74f0061c2fbc cited By 33 H. Sone E.-C. Yeh T. Nakaya J.-H. Hung K.-F. Ma C.-Y. Wang S.-R. Song T. Shimamoto article Chen2007243 In order to understand the fault zone architecture and mechanisms that caused the Chi-Chi earthquake, the Chelungpu drilling project was conducted during April 2000 through a collaborative project between Japan and Taiwan. In this study, chemical and mineralogical variations within the overall Chelungpu fault zone, including variations between less damaged host rocks, damaged zones, and fault cores caused by the Chi-Chi earthquake were examined. Slopes of TiO2 immobile isocons were consistently &gt; 1 for analyses comparing host rocks with rocks from damaged zones or with gouges from fault cores, indicating that volume loss occurred in damaged zones and the fault cores. These results strongly imply that pervasive fluid infiltration occurred within the fault zone. Volume loss within the damaged zone and fault core is interpreted to result from a two-stage process involving: (i) coseismic mechanical wearing and/or dissolution in the fault core, and (ii) fluid infiltration within the fault zone during postseismic and interseismic periods along cracks caused by seismic failure. Semi-quantitative XRD analysis indicates that the kaolinite content consistently increases from the less damaged host rocks to the damaged zone and gouges in each fault core. Mineralogic changes indicate that pervasive acidic fluid infiltration occurred within the fault zones and reacted with the feldspars or muscovite to form kaolinite. Enrichment of kaolinite and illite found in the fault zones of southern drilling site could play some role on the slipping behavior of the southern part of the Chelungpu fault. Greater volume loss in the fault core may have resulted from moderate permeability, combined with the very fine grain nature of pulverized material in the fault core, which enhanced chemical reactions including transformation of feldspars and muscovite to clay minerals. The study results indicate that pervasive fluid infiltration occurred and changed the mineralogical and chemical architecture of fault zones caused by the cyclic earthquakes. © 2007 Elsevier B.V. All rights reserved. 2007 English 00401951 10.1016/j.tecto.2007.01.025 Tectonophysics 443 243-254 Department of Earth Sciences, National Central University, Taiwan; Department of Earth and Planet. Sciences, University of Tokyo, Japan; Institute of Applied Geology, National Central University, Taiwan; Department of Geosciences, National Taiwan University, Taiwan 3-4 active fault; chemical composition; Chi-Chi earthquake 1999; core analysis; fault zone; mineralogy, Asia; Eurasia; Far East; Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-34648834432&doi=10.1016%2fj.tecto.2007.01.025&partnerID=40&md5=703d38bd828e7df5aeb2d321aaec95a4 cited By 21 W.-m.D. Chen H. Tanaka H.-j. Huang C.-b. Lu C.-y. Lee C.-Y. Wang article Ma200733 2007 English 18168957 10.2204/iodp.sd.s01.10.2007 Scientific Drilling Integrated Ocean Drilling Program 33-34 Department of Earth Science and Institute of Geophysics, National Central University, No.300, Johngda Rd., Johngli City, Taoyuan County 32001, Taiwn, Taiwan; Solid Earth Science Group, Department of Earth and Planetary Sciences, The University of Tokyo, Faculty of Science Building #1, Hongou 7-3-1, Bunkyo-ku,ing Tokyo, 113-0033, Japan 1 SUPPL. 1 https://www.scopus.com/inward/record.uri?eid=2-s2.0-78651566829&doi=10.2204%2fiodp.sd.s01.10.2007&partnerID=40&md5=1381297ab6bd7b1d4ed8ac3fbb8e3ebb cited By 1 K.-F. Ma H. Tanaka article Wu2007295 The results of this nannofossil analysis supply essential information for determining the formation boundaries in the upper Pliocene to Pleistocene. These results also verify the existence of a repetition fossil zone. The TCDP well-A was sunk through the soft fine-grain muddy sandstone and mudstone dominated formations of the Pliocene and Pleistocene in the Taichung area. This study determines methods for providing core preservation in wells at fault zones and establishes a nannofossil biostratigraphy for the integrated Taiwan Chelungpu-fault Drilling Project (TCDP). Good core fabrics are useful for core description and sampling. In this present study, over 400 meters of subsurface cores were covered in resin and slabbed. Digitized images were created for all the core fabrics. More than 150 rock samples were analyzed for nannofossils to give a detailed appraisal of the biostratigraphic column of TCDP well-A. A fossil zone at a depth interval of 431 - 869 m is a NN16 - 18 biozone. This zone is within the Cholan Formation, a lithologic stratigraphy in northern and central Taiwan. The depth interval 883-1226 m is NN15, and is within the Chinshui Shale. The Chelungpu fault is composed of five major shear zones. These are all found at depth within the marine Chinshui Shale. At a depth interval of 1293.37 - 1710 m is a NN12 - 14 biozone; this interval is within the Kueichulin Formation. Interestingly, both the interval beneath 1714 m and the nannofossil zone near the well bottom are NN16 - 18 (Cholan Formation), indicating a repeat of the Cholan Formation. The lowest fossil zone is also abundant in secondary reworked fossils in its assemblages. Hence, the repetition of the younger fossil zone, NN16 - 18, at the bottom of the well verifies the subsurface position of the Sanyi Fault and indicates that TCDP well-A must have passed through it. 2007 English 10170839 10.3319/TAO.2007.18.2.295(TCDP) Terrestrial, Atmospheric and Oceanic Sciences 18 295-325 Exploration and Development Research Institute, Chinese Petroleum Corporation, Miaoli, Taiwan; Department of Earth Sciences, Institute of Geophysics, National Central University, Chung-Li, Taiwan; Department of Earth Science, National Taiwan Normal University, Taipei, Taiwan; Institute of Applied Geophysics, National Taiwan Ocean University, Keelung, Taiwan 2 biostratigraphy; core analysis; lithology; mudstone; nanofossil; Pliocene-Pleistocene boundary; shear zone; slab, Asia; Eurasia; Far East; Taichung; Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-34547562778&doi=10.3319%2fTAO.2007.18.2.295%28TCDP%29&partnerID=40&md5=df6763ad6f5f7615993f9e75c9aa86a9 cited By 6 J.-C. Wu S.-T. Huang M.-H. Wang C.-C. Tsai W.-W. Mei J.-H. Hung T.-Y. Lee K.-M. Yang K.-F. Lee article Song2007243 The main objective of the Taiwan Chelungpu-fault Drilling Project (TCDP) was to conduct an in-depth probe into a fault zone of recent major activity so as to gain a better understanding of and more insight into the physical, mechanical and chemical properties involved. By the end of 2004, with the completion of the drilling of Hole-A, cuttings from 0 to 431.34 m and cores from a 431.34- to 2003.26-m depth had been obtained. Stratigraphically, the Pliocene to Pleistocene Cholan Formation is found from the surface to a 1029-m depth and is predominantly composed of sandstone and sandstone-siltstone alternations with weak to intense bioturbation. The Pliocene Chinshui Formation is observed from a depth of 1029- to 1303-m and predominantly consists of siltstone with weak bioturbation. From 1303- to 1712-m down there is the late Miocene to early Pliocene Kueichulin Formation which is predominantly composed of massive sandstone with minor siltstone. Below 1712 m, the Formation again resembles the younger Cholan Formation with mollusca-rich, thick, layered shale and heavy bioturbated sandstone. Four types of fault-related rocks are identified in the cores. They are the fault breccia, gouges, foliated and non-foliated cataclasites and pseudotachylytes. At least six major fault zones are found in the cores: FZ1111, FZ1153, FZ1220, FZ1580, FZ1712, and FZ1812. Among these, FZ1111 most probably corresponds to the slip surface of the Chi-Chi earthquake, the Chelungpu fault, while FZ1712 very likely represents the Sanyi fault. 2007 English 10170839 10.3319/TAO.2007.18.2.243(TCDP) Terrestrial, Atmospheric and Oceanic Sciences 18 243-269 Department of Geosciences, National Taiwan University, Taipei, Taiwan; Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, Kochi, Japan; Department of Earth Sciences, Institute of Geophysics, National Central University, Chung-Li, Taiwan 2 chemical property; fault zone; lithology; lithostratigraphy; mechanical property; Miocene; physical property; Pleistocene; Pliocene, Asia; Eurasia; Far East; Taiwan, Mollusca https://www.scopus.com/inward/record.uri?eid=2-s2.0-34547604009&doi=10.3319%2fTAO.2007.18.2.243%28TCDP%29&partnerID=40&md5=9b0f14ad8d522907aaad3aa9e7ba7fdd cited By 51 S.-R. Song L.-W. Kuo E.-C. Yeh C.-Y. Wang J.-H. Hung K.-F. Ma article Wang20071233 Friction is commonly considered an important factor in controlling earthquake rupture. In this work, it is assumed that viscosity is also a significant factor. A strike-slip-type, two-body spring-slider model in the presence of both friction and viscosity is applied to approximate the rupture processes of an earthquake along the fault-striking direction. Results show that in addition to friction, viscosity is also an important factor in controlling rupture. The Ms 7.6 Chi-Chi earthquake which struck central Taiwan on 20 September 1999, ruptured a 100-km-long east-dipping transpressive fault (the Chelungpu fault). Measured and inferred results show that there are differences in physical properties between the northern and southern segments of the fault. Simulation results from a two-body model can explain the differences in displacement, velocity, acceleration, and predominant period between the two fault segments. 2007 English 00371106 10.1785/0120060042 Bulletin of the Seismological Society of America 97 1233-1244 Institute of Earth Sciences, Academia Sinica, P.O. Box 1-55, Nangang, Taipei 115, Taiwan 4 Approximation theory; Computer simulation; Dynamics; Friction; Mathematical models; Physical properties; Viscosity, Earthquake rupture; Fault-striking direction; Transpressive fault, Earthquakes, Chi-Chi earthquake 1999; displacement; earthquake magnitude; earthquake rupture; friction; simulation; strike-slip fault; transpression; viscosity, Asia; Eurasia; Far East; Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-34548078708&doi=10.1785%2f0120060042&partnerID=40&md5=07c25652ebfe05c72dc44e9822764505 cited By 14 J.-H. Wang article Ma2006473 Determining the seismic fracture energy during an earthquake and understanding the associated creation and development of a fault zone requires a combination of both seismological and geological field data. The actual thickness of the zone that slips during the rupture of a large earthquake is not known and is a key seismological parameter in understanding energy dissipation, rupture processes and seismic efficiency. The 1999 magnitude-7.7 earthquake in Chi-Chi, Taiwan, produced large slip (8 to 10 metres) at or near the surface, which is accessible to borehole drilling and provides a rare opportunity to sample a fault that had large slip in a recent earthquake. Here we present the retrieved cores from the Taiwan Chelungpu-fault Drilling Project and identify the main slip zone associated with the Chi-Chi earthquake. The surface fracture energy estimated from grain sizes in the gouge zone of the fault sample was directly compared to the seismic fracture energy determined from near-field seismic data. From the comparison, the contribution of gouge surface energy to the earthquake breakdown work is quantified to be 6 per cent. ©2006 Nature Publishing Group. 2006 English 00280836 10.1038/nature05253 Nature 444 Nature Publishing Group 473-476 Department of Earth Sciences, National Central University, Chung-Li 32054, Taiwan; Department of Earth and Planetary Sciences, University of Tokyo, Tokyo 113-0033, Japan; Department of Geosciences, National Taiwan University, Taipei 10617, Taiwan; Disaster Prevention Research Institute, Kyoto University, Kyoto 611-0011, Japan; National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan; Kochi Institute for Core Sample Research, Agency for Marine-Earth Science and Technology, Kochi 783-8502, Japan; Department of Geology and Mineraology, Kyoto University, Kyoto 606-8501, Japan 7118 Drilling platforms; Earthquake effects; Energy dissipation; Interfacial energy; Project management; Surface phenomena, Near field; Rupture processes; Seismic fracture energy; Slip zone, Seismology, borehole; Chi-Chi earthquake 1999; drilling; fault gouge; fault slip; fault zone; grain size; seismometry; surface energy, article; earthquake; energy transfer; geology; particle size; priority journal; surface property; Taiwan; thickness, Asia; Eurasia; Far East; Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-33751328490&doi=10.1038%2fnature05253&partnerID=40&md5=a0b0bce1db6e91139f70e7f43658cd97 cited By 213 K.-F. Ma H. Tanaka S.-R. Song C.-Y. Wang J.-H. Hung Y.-B. Tsai J. Mori Y.-F. Song E.-C. Yeh W. Soh H. Sone L.-W. Kuo H.-Y. Wu article Doan2006 [1] Hydraulic diffusivity controls fluid pressure and hence affects effective normal stress during rupture. Models suggest a particularly spectacular example of fluid pressurization during the Mw = 7.6 1999 Chichi earthquake when pressurization may have reduced high-frequency shaking in the regions of large slip if the fault was sufficiently sealed. We investigate in situ hydraulic diffusivity which is the key parameter in such models through a cross-hole experiment. We find a diffusivity of D = (7 ±1) × 10-5 m2/s, which is a low value compatible with pressurization of the Chelungpu fault during the earthquake. In most poroelastic media, the hydraulic storativity 5 lies between 10-7 and 10 -5, so that the transmissivity T along the fault zone is comprised between 10-11 m2/s and 10-9 m2/s. The corresponding permeability (10-18-10-16 m2) is at most one hundred times larger than the value obtained on core samples from the host rock. The fault zone is overpressurized by 0.06 to 6 MPa, which is between 0.2% and 20% of the lithostatic pressure. Copyright 2006 by the American Geophysical Union. 2006 English 00948276 10.1029/2006GL026889 Geophysical Research Letters 33 American Geophysical Union Earth Science Department, University of Santa Cruz, Santa Cruz, CA, United States; National Central University, Chung-li, Taiwan; Disaster Prevention Research Institute, Kyoto University, Kyoto, Japan; Earth Science Department, Earth and Marine Sciences Building, University of Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, United States; Disaster Prevention Research Institute, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan; National Central Universijy, Chung-li 320-54, Taiwan 16 Carrier communication; Core samples; Diffusion; Earthquakes; Fluid dynamics; Mathematical models; Pressure effects; Stress analysis, Fault zone; Hydraulic diffusivity; Lithostatic pressure; Poroelastic media, Hydraulic fracturing, crosshole seismic method; diffusion; earthquake; fault; fluid pressure; hydraulic conductivity; poroelasticity, Asia; Eurasia; Far East; Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-33845662656&doi=10.1029%2f2006GL026889&partnerID=40&md5=a115401e85bbca02e2fc6e568abb80f5 cited By 66 M.L. Doan E.E. Brodsky Y. Kano K.F. Ma article Hirono2006 The Taiwan Chelungpu-fault Drilling Project (TCDP) was undertaken in 2002 to investigate the faulting mechanism of the 1999 Taiwan Chi-Chi earthquake. Hole B penetrated the Chelungpu fault, and recovered core samples from between 948.42 m and 1352.60 m depth. Three zones, marked 1136mFZ, 1194mFZ and 1243mFZ, were recognized in the core samples as active fault-zones within the Chelungpu fault. Multi-Sensor Core Logger measurements revealed lower densities and higher magnetic susceptibilities within the black gouge zones in all three fault zones. Even though the fault zone that slipped during the 1999 earthquake has not been identified, higher magnetic susceptibilities indicate that frictional heating has taken place in the Chelungpu fault. Copyright 2006 by the American Geophysical Union. 2006 English 00948276 10.1029/2006GL026133 Geophysical Research Letters 33 Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, Nankoku, Japan; Department of Natural Environmental Science, Faculty of Science, Kochi University, Kochi, Japan; Department of Geology and Mineralogy, Graduate School of Science, Kyoto University, Kyoto, Japan; Institute for Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan; Center for Deep Earth Exploration, Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan; Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology, Yokosuka, Japan; Center for Advanced Marine Core Research, Kochi University, Kochi, Japan; Department of Geosciences, National Taiwan University, Taipei, Taiwan; Institute of Geophysics, National Central University, Jhongli, Taiwan; Center for Deep Earth Exploration, Japan Agency for Marine-Earth Science and Technology, 3173-25 Showa-machi, Kanazawa-ku, Yokohama, 236-0001, Japan; Department of Natural Environmental Science, Faculty of Science, Kochi University, 2-5-1 Akebono-cho, Kochi 780-8520, Japan; Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, Nankoku 783-8502, Japan; Institute of Geophysics, National Central University, Jhongda Road, Jhongli 32001, Taiwan; Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosukashi, 237-0061, Japan; Institute for Geo-Resources and Environment, National Institute of Advanced Industrial Science and Technology, Tsukuba, 305-8567, Japan; Center for Advanced Marine Core Research, Kochi University, 2-5-1 Akebono-cho, Kochi 780-8520, Japan; Department of Geology and Mineralogy, Graduate School of Science, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501, Japan; Department of Geosciences, National Taiwan University, Roosevelt Road, Taipei, 106, Taiwan 15 Earthquakes; Heating; Magnetic susceptibility; Project management; Sensors; Tribology, Chemical properties; Fault rocks, Geomorphology, Chi-Chi earthquake 1999; fault gouge; magnetic susceptibility; physicochemical property; rock, Asia; Eurasia; Far East; Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-33845670299&doi=10.1029%2f2006GL026133&partnerID=40&md5=3f64f0bd58d94891df45e144925e67c7 cited By 79 T. Hirono W. Lin E.-C. Yeh W. Soh Y. Hashimoto H. Sone O. Matsubayashi K. Aoike H. Ito M. Kinoshita M. Murayama S.-R. Song K.-F. Ma J.-H. Hung C.-Y. Wang Y.-B. Tsai article Wang2006 On 20 September 1999, the Ms7.6 Chi-Chi earthquake raptured the Chelungpu fault in central Taiwan. Integrating observed and inversed results of source parameters, the fracture energy, Eg. and frictional energy, Ef, on the fault and its northern and southern segments are estimated. Together with given values of strain energy, ΔE, and seismic radiation energy, Es, the seismic efficiency, i.e., η = Es/ΔE, and the radiation efficiency, i.e., ηR = Es/(Es + Eg), are evaluated. The average fracture energy per unit area, G, is also calculated from Eg. The frictional heat caused by dynamic frictional stress is calculated from Ef. Results show a marked difference in source properties between the two segments. The average frictional and ambient stress levels on the two segments are estimated. The total energy budget of and heat generated by the earthquake are elucidated based on a two-dimensional faulting model with frictional heat. Both observed and calculated results suggest the possible existence of fluids, which produced suprahydrostatic gradients, on the fault during faulting. Lubrication and thermal fluid pressurization might play a significant role on rupture. Copyright 2006 by the American Geophysical Union. 2006 English 21699313 10.1029/2005JB004018 Journal of Geophysical Research: Solid Earth 111 Blackwell Publishing Ltd Institute of Earth Sciences, Academia Sinica, P.O. Box 1-55, Nangang, Taipei 115, Taiwan 11 Chi-Chi earthquake 1999; earthquake magnitude; earthquake rupture; energy budget; faulting; seismicity; source parameters, Asia; Eurasia; Far East; Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-34547557596&doi=10.1029%2f2005JB004018&partnerID=40&md5=164ac9aa6323226cbba73ac139970127 cited By 24 J.-H. Wang article Mori2002255 2002 English 00963941 10.1029/2002EO000180 Eos 83 American Geophysical Union 255 Disaster Prevention Research Institute, Kyoto University, Japan; Geological Survey of Japan, AIST, Tsukuba, Japan; National Central University, Jungli, Taiwan 23 https://www.scopus.com/inward/record.uri?eid=2-s2.0-0011072550&doi=10.1029%2f2002EO000180&partnerID=40&md5=99c381adda310ec40a8586da7898b763 cited By 13 J. Mori H. Ito C.-Y. Wang article Chen2002 The geometrical structure of the responsible faults of the 20 September 1999 Chi-Chi, Taiwan, earthquake (ML = 7.3, Mw = 7.6) and its aftershocks can be clearly depicted by well-located hypocenters and focal mechanisms of large aftershocks. The mainshock and two large aftershocks with ML = 6.8 were characterized by thrust faulting along a N-S striking fault plane dipping to the east. The underground structure of the Chelungpu fault, which is probably merging with the decollement beneath the Western Foothills, can be clearly associated with the seismicity pattern and the focal mechanisms of the three largest events. A group of deeper aftershocks including two moderate events (ML = 6.3 and 6.0, respectively) were located to the southeast of the mainshock along a fault plane dipping steeply to the west down to a depth of about 30 km. Our results suggest that the spatial pattern of the aftershocks in the southern part of the source area can be interpreted by a conjugate-fault system. This conjugate-fault system is comprised of the gently east-dipping Chelungpu fault and a steeply west-dipping deeper fault zone. Copyright 2002 by the American Geophysical Union. 2002 English 00948276 10.1029/2001GL014250 Geophysical Research Letters 29 Blackwell Publishing Ltd Institute of Earth Sciences, Academia Sinica, P.O. Box 1-55, Nankang, Taipei, Taiwan; Institute of Geophysics, National Central University, Chung-Li, Taiwan 8 Earthquakes; Geophysics; Underground structures, Chi-Chi , Taiwan; Conjugate faults; Earthquake sequences; Focal mechanism; Geometrical structure; Seismicity pattern; Spatial patterns; Thrust faulting, Faulting https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037092375&doi=10.1029%2f2001GL014250&partnerID=40&md5=5db990901461a59c7cf18e2eea5d699d cited By 34 K.-C. Chen B.-S. Huang J.-H. Wang H.-Y. Yen article Tanaka2002227 The Chelungpu fault, a reverse fault with left lateral component dipping moderately to the east, was activated by the Chi-Chi earthquake (Mw = 7.6) in 21 September, 1999 with maximum vertical and lateral offsets of 5.6 m and 9.8 m. Characteristics of earthquake and related phenomena are contrasting between northern and southern regions along the Chelungpu fault. The northern region has (1) larger displacements (4 to 9 m), (2) low frequency seismic waves with higher velocity of slip surface, and (3) less disastrous except the most northern area compared to those in the southern region. Drilling into the Chelungpu fault was thus conducted at two locations, northern (Fengyuan) and southern (Nantou) sites, and successfully completed in March 2001. The project was motivated to explore the fundamental controlling factors of the mode of slip motion at northern and southern regions through analysis of intrafault materials. Meso- and microstructural examinations and measurements of static/ dynamic physical properties have been conducted for each drill core. The ongoing analyses have shown interesting results: (1) fault zone architecture is totally different between the northern and southern fault zones. The rocks are mainly composed of random fabric fault breccia with extremely thin fault gouge in the northern core, whereas the foliated fault breccia is dominantly associated with ultracataclasite and pseudotachylite in the southern core, (2) possible fault zones activated by the Chi-Chi earthquake can be listed up by combining geological, geophysical logging and reflection seismic data, which are 225 m and 330 fracture zones in the core from northern well and 177 m and 180 m fracture zones in the core from southern well, (3) water contents of the core of the 225 m rupture zone in the northern well attains up to 45 vol.%, and (4) some temperature rises were detected at 330 m fracture zone in the northern well and 180 m fracture zone in the southern well by temperature logging, which could be attributed to residual heat generated during the Chi-Chi earthquake or postseismic influx of hydrothermal fluid into the fault zones. 2002 English 10170839 10.3319/TAO.2002.13.3.227(CCE) Terrestrial, Atmospheric and Oceanic Sciences 13 Chinese Geoscience Union 227-251 Institute of Geophysics, National Central University, Chung-Li, Taiwan 3 breccia; Chi-Chi earthquake 1999; dip-slip fault; drilling; fault zone; microstructure; reverse fault, Chelungpu Fault; Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036752072&doi=10.3319%2fTAO.2002.13.3.227%28CCE%29&partnerID=40&md5=22abcf045b1771911d87be39765c5bec cited By 61 H. Tanaka C.-Y. Wang W.-M. Chen A. Sakaguchi K. Ujiie H. Ito M. Ando article Wang200237-1 The Chelungpu fault was activated by the 1999 Chi-Chi earthquake (Mw = 7.6), Taiwan. This fault exhibited extraordinarily large surface ruptures (up to 9.8 m) as well as underground fault slippages (up to 12 m) during the earthquake. These large displacements were concentrated along the northern portion of the fault, 40 km north of the epicenter. To prepare data for the future drilling of deep wells in this area, many shallow seismic reflection surveys were conducted to investigate the sites. An approximate 3D structure of the fault surface can be deduced by this cost-effective approach. Although the depth penetration may be limited (e.g., 3 km), the method still provides reliable information to study large ruptures, and to better plan future deep wells. 2002 English 00948276 10.1029/2001gl014496 Geophysical Research Letters 29 American Geophysical Union 37-1-37-3 Institute of Geophysics, National Central University, Chung-Li 32054, Taiwan 16 Cost effectiveness; Seismology; Structure (composition); Surveys, Fault slippages, Earthquakes, borehole; earthquake rupture; fault slip; seismic reflection; seismic survey, Chelungpu Fault; Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-0037104909&doi=10.1029%2f2001gl014496&partnerID=40&md5=8f749f97d58bf6c659ba5e7e206df647 cited By 20 C.-Y. Wang C.-L. Li H.-Y. Yen article Wang2002153 Two shallow holes (∼300m) were drilled to uncover cores to study the properties of the Chelungpu fault, which was activated during the 1999 Chi-Chi earthquake (Mw=7.6), Taiwan. Before drilling, we collected seismic reflection data near the wells to aid the drilling processes. The depths predicted by the seismic reflection sections proved to be very close to the drilling results. These seismic sections also provided details of underground 2D structures, which are of help in clarifying the relationship of the well with the neighboring geology. Besides this, we also present several seismic sections describing the undisturbed structures on the Chelungpu fault's footwall side opposite the violated hanging-wall side. A detachment type of movement is suggested to explain this extraordinary phenomenon. Finally, a combination of seismic and electric methods was implemented to explore the near-surface structure of the Sanyi fault, which is believed to be the counterpart of the Chelungpu fault but at a deeper location. The results show that the Sanyi fault is old and has ceased its movement, perhaps not having been involved in the Chi-Chi earthquake's action. 2002 English 10170839 10.3319/TAO.2002.13.2.153(T) Terrestrial, Atmospheric and Oceanic Sciences 13 Chinese Geoscience Union 153-170 Institute of Geophysics, National Central University, Chung-Li, Taiwan, Taiwan 2 drilling; earthquake; fault; seismic reflection, Chichi; Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036019693&doi=10.3319%2fTAO.2002.13.2.153%28T%29&partnerID=40&md5=906773ecca389dc380e90e5bc5335545 cited By 14 C.-Y. Wang H. Tanaka J. Chow C.-C. Chen J.-H. Hong article Wang2002211 Several seismic reflection surveys were conducted to investigate the seismogenic structure of the 1999 Chi-Chi earthquake (Mw=7.6) in central Taiwan. Two 40 km-long seismic profiles that crossed the area near the epicenter were acquired using the deep reflection method with a targeting depth of 10 km, to search for the decollement boundary. One of the obtained sections shows a clear reflection event that dips to the east by 40° until reaching a depth of 8 km where the earthquake's source was located. This slant event is unambiguously related to the thrusting Chelungpu fault surface. The abundant eastward dipping reflectors on the deep reflection sections faithfully describe thrusting features predicted by the earthquake faulting model. Besides these deep reflections, we also used many shallow seismic reflection lines to delineate the structures in the northern portion of the fault zone, where large ruptures (about 10 m) occurred both on the surface and underground. The 3D structure of the fault surface can be deduced using this cost-effective approach. Although the depth imaged may be limited (e.g., 3 km), shallow seismic data still provides reliable information for the study of large ruptures, and to make better plans for deep wells that might be drilled in this area in the future. 2002 English 10170839 10.3319/TAO.2002.13.3.211(CCE) Terrestrial, Atmospheric and Oceanic Sciences 13 Chinese Geoscience Union 211-226 Institute of Geophysics, National Central University, Chung-Li, Taiwan 3 Chi-Chi earthquake 1999; fault; geological mapping; seismic reflection, (Central); Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036752541&doi=10.3319%2fTAO.2002.13.3.211%28CCE%29&partnerID=40&md5=2bc9ee63fbe21b99d604f7bedeb4ceae cited By 39 C.-Y. Wang C.-L. Li F.-C. Su M.-T. Leu M.-S. Wu S.-H. Lai C.-C. Chern article Huang2002253 Stratigraphy, sedimentary facies, and deformation characteristics of drill cores from Fengyuan and Noutou wells reveal important attributes for the westmost portion of active Chelungpu thrust fault and contrasting deformation mechanisms between the north and south ends. Stratigraphy of the Fengyuan well (including BH-1 and BH-1A boreholes) is composed of three major units, including the upper Miocene to Pliocene Kueichulin Formation (455.4-224.7 m), the Pliocene Chinshui Shale (224.7-3.9 m) and recent terrace deposits (3.9-0 m). The Kueichulin Formation comprises three upward coarsening, tide-dominated delta parasequences with sandstone and sandstone-Shale alternations. The Chinshui Shale is dominated by shallow marine facies with siltstone, mudstone and fine-grained sandstone. Shallow marine facies are occasionally intercalated with tide-dominated delta deposits. Terrace deposits are characterized by paleosol, yellowish mud, mottled leaching soil and thin pebble layers. The Chi-Chi earthquake slip zone is located at a transgressive deposit, which is also the sequence boundary between the Kueichulin Formation and the Chinshui Shale. Other two major brecciated shear zones are also the parasequence boundaries within the Kueichulin Formation. Stratigraphic sequence of the Nantou well (CLF-2) is composed of the Pleistocene Toukoshan Formation (211.9-177 m) in the footwall, and the Chinshui Shale (177-8.7 m) and terrace deposits (8.7-0 m) in the hangingwall. The Toukoshan Formation is characterized by alternation of conglomerates and yellowish fine-grained deposits with drifted pebbles, an indication of braided fluvial deposits. The Chinshui Shale comprises alternating shallow marine and tidal deposits. The shallow marine face is dominated by mudstone, siltstone and fine-grained sandstone with moderate to high degree of bioturbation. Terrace deposits are characterized by yellowish gray mud, pebble layer, and mottled paleosol. Overall, shear zones in the Nantou well is characterized by foliated gouge or breccia as opposed to breccia or gouge of random fabrics in the Fengyuan well. 2002 English 10170839 10.3319/TAO.2002.13.3.253(CCE) Terrestrial, Atmospheric and Oceanic Sciences 13 Chinese Geoscience Union 253-278 Exploration/Development Res. Inst., Chinese Petroleum Corporation, 1 Ta Yuan, Wen Shan, Miaoli 36010, Taiwan 3 Chi-Chi earthquake 1999; deformation; fault zone; sequence stratigraphy; Tertiary; thrust fault, (Central); Taiwan https://www.scopus.com/inward/record.uri?eid=2-s2.0-0036752985&doi=10.3319%2fTAO.2002.13.3.253%28CCE%29&partnerID=40&md5=01f1bd497ede3f94a5d3d87811875ef3 cited By 19 S.-T. Huang J.-C. Wu J.-H. Hung H. Tanaka