The topics above are offered by ICDP's Operational Support Group (OSG), a small team of scientists, engineers and technicians to assist in project planning and management. 

Downhole Monitoring

Permanent Downhole Monitoring

To summarize the current state of the art in Permanent Downhole Monitoring (PDM) an outlook and recommendation for future development and research for both the service industry as well as academia is provided. We further propose suggestions and decision aids for Principal Investigators (PI) and scientists referring their selection criteria for an array system on the basis of reliability, sensitivity, risk of failure and investment cost.  

Worldwide Field Installations

  • GONAF/TR

    A deep Geophysical Observatory at the North Anatolian Fault using a Borehole-Based Seismometer Network at the Eastern Sea of Marmara

    Instrument array at 298 m with sensor (2 Hz / 15 Hz), at 225.64 m 1 sensor (1 Hz), at 153.28 m 1 sensor (1 Hz), at 74.89 m 1 sensor (1 Hz)

    8 ½” borehole, static temperature <40 °C, max. depth 300 m, still operating

    Oct. 2012: Successfully cemented to surface in the hole by means of a PVC pipe string. Cementing string left in the hole. All sensors in operation.

  • Earth Scope SAFOD-MH/USA

    SAFOD as part of Earth Scope has drilled and instrumented an inclined borehole across the San Andreas Fault Zone to a depth of 3.2 km, targeting a repeating microearthquake source. 

    The array includes: Fiber-optic cable head, DS325 locking arm, Pinnacle high-temperature tiltmeter, GERI DS250/DS150 adaptor, GERI DS150 65m interconnect, GERI DS150 seismometer, GERI DS150 65m interconnect, GERI DS150 seismometer, GERI DS150 3m interconnect and weight bar.

    8 ½” borehole, 125 °C static temperature, max. depth 3998 m, longest operation: 2 months

    Sept. 2006: the array had to be recovered due to cable transmission failures and gas influx in the instrument packages. Waiting on NSF approval for a new installation since.

  • Earth Scope SAFOD-PH/USA

    SAFOD as part of Earth Scope has drilled and instrumented a vertical borehole across the San Andreas Fault Zone to a depth of 2,3 km, targeting earthquake source from the San Andreas fault prior to drilling the main hole (MH).  

    The array included: 80 stations of P/GSI’s 3c analogue geophones.

    8 ½” borehole, 115 °C static temperature, max. depth 2347 m (7112 ft), longest operation: 16 months

    Mar. 2004: the array had to be recovered due to an intersection of the MH with the PH trajectory and array failure as well as gas influx in the cable jacket.

  • Chelungpu/Taiwan

    The objective for the Taiwan Chelungpu-fault (TCDP) installation is to monitor a the fault where large displacements occurred during the Chi-Chi earthquake and to measure the physical properties and mechanical behaviour, as well as to document the state of stress of the rocks above and below the fault zone over a long time period.

    The instrument array included: pT gauges, chemical sensors, U-tube sampling line and 7 stages of 3c seismometer (analogue) package.

    6 ¼” borehole, 48 °C static temperature, max. depth 1300 m, still operating

    Dec. 2004: successful installation on steel rope, cables and tube attached to rope with bands. Sensors in operation

  • Corinth/GR

    The investigation of the mechanical behaviour of active faults by means of downhole monitoring the physics of earthquakes and aseismic fault motion.

    The instrument array included: pT gauges, optical strainmeter, 6 pcs electrical electrodes and a 3c accelerometer package.

    6 ¾” borehole, 31 °C static temperature, max. depth 1001 m, still operating

    Sept. 2002: successful installation on wireline and outside the cemented casing. Sensors in operation

  • Mallik/CA

    The investigation of the mechanical behaviour of active faults by means of downhole monitoring the physics of earthquakes and aseismic fault motion.

    The instrument array included: pT gauges, optical strainmeter, 6 pcs electrical electrodes and a 3c accelerometer package.

    6 ¾” borehole, 31 °C static temperature, max. depth 1001 m, still operating

    Sept. 2002: successful installation on wireline and outside the cemented casing. Sensors in operation

  • Long Valley/USA

    The objective of this installation is to monitor over long periods the mid-crustal deformation in a magmatic-seismogenetic dome of the Long Valley caldera in east-central California.

    The instrument array included: 1c – strainmeter, pressure gauge and 2 stages of 3c seismometer (analogue) packages.

    6 ¾” borehole, 110 °C static temperature, max. depth 2996 m, still operating

    Sept. 1998: successful installation on steel rope, cables attached to rope with bands. Sensors in operation, strainmeter was lost shortly after installation.