by Francois-Henri Cornet, Ioannis Vardoulakis

The objective of the Corinth Rift Laboratory (CRL) is to integrate surface and downhole observations for a better understanding of the physics of faulting in an extensional tectonic regime, with special attention to interactions between fluids and active faults. Its development has been decided after an ICDP sponsored workshop held in Athens in 1997 which provided means to identify its main objective and demonstrated its complementarity with the two other ongoing fault drilling projects, namely the San Andreas drilling project in a transform fault environment and the project off the western Japanese cost in a subduction zone environment. The Corinth Rift is opening at a rate of 1.5 cm/year, with its southern shore uplifting at a rate close to 1 mm/year. It is one of the most seismically active zones in Europe. CRL will include, in addition to the local research infractructure facility, an efficient database common to all participants and widely accessible through the web. CRL presently includes a set of five European funded projects. In addition to the Deep Geodynamic Laboratory (DGLab) drilling project, CORSEIS is centred on surface geophysical networks, 3F-Corinth places emphasis on geochemical and geophysical interactions between fluids and faults as well as on seismic reconnaissance and numerical modelling, AEGIS corresponds to the Information Science Technology component of the project, and ASSEM develops sensors for offshore monitoring. In addition, national agencies (PLOUTON for Greece, GDR-Corinth for France, GRECO for Germany) bring equipment, personnel for maintenance and some academic expertise for more theoretical reflection on results obtained in situ. The only funds presently available for drilling come through the DGLab project. The site for DGLab is located in Aigion, a city on the southern shore of the Corinth Gulf, which was hit by a magnitude 6.5 earthquake in 1995. On this location, the DGLab drilling project aims at instrumenting two boreholes (1200 and 600 m deep), which intersect the recently activated Aigion fault. Particular emphasis is placed on documenting the role of fluids on fault behaviour and the role of earthquake faulting on regional hydrogeology thanks to the continuous downhole monitoring of various parameters characteristics of the fault fluid flow conditions. The first year of DGLab activity has resulted in identifying the local geological structure where the boreholes are to be drilled and in producing the first draft of a local geological map together with some information on main faults structures. Four seismic profiles cumulating 33 km of seismic lines (three of them perpendicular to the Heliki and Aegion faults, one of them parallel to the faults) outline the absence of simple reflections. This is taken to be the consequence of the complexity of the regional faulting system. But refraction data provides clear identification of targeted tertiary limestone, below the recent conglomerates. These results, together with observations from a 200 m deep drill hole, suggests that limestone will be hit around 820 m, in the northern hanging wall of Aigion fault. Dip of Heliki fault has been measured at five different sites. Results outline a dip ranging from 70° when the fault remains in limestone to 55° when it is entirely in conglomerates, and about 60° when it interfaces limestone and conglomerates. This has prompted the recommendation to deepen the wells and to locate them further away from the fault trace than initially planned. Indeed, this will ensure that the fault is not intersected by the 1200 m borehole where it cuts through the conglomerates but where it passes through the carbonates. But these deeper conditions are not compatible with presently available budget. Therefore, the purpose of this proposal is to apply to the ICDP for additional funding which will permit the deepening of the wells without jeopardizing the main scientific content of the overall project.

• (No objectives found in database. Record is incomplete and needs some manual curation)

Active Faults, Aigion, CORINTH, Dglab, Earthquakes, Geothermy, Greece, ICDP-2002/13, Rift Zones

Latitude: 38.25567, Longitude: 22.07067