Geophysical Borehole Observatory for Türkiye

23 Jan

In one of the industry's firsts Gaiacode will design, build and install a multidisciplinary geophysical borehole observatory at the North Anatolian Fault in Western Türkiye. In a contract just signed with the German Earth Science Research Center (GFZ) in Potsdam the observatory will consist of a three component, low noise ALPHA broadband seismometer, a dilatometer, a strainmeter and a pore pressure sensor. These instruments are all designed and built in house by Gaiacode. These sensors will be augmented by a MEMS accelerometer, a temperature probe and a three axis 4.5 Hz geophone, which are supplied by other vendors but integrated into the observatory by us.

Our company is well positioned to build and deploy such a complex borehole observatory. Gaiacode's founder, Cansun Güralp, has more than three decades of experience in designing, building and installing borehole seismometers all over the world, including in drillholes in the oceans.

The new observatory is a major extension of the GONAF-Project, a joint research initiative by the GFZ and the Turkish Disaster and Emergency Management Presidency (AFAD). The acronym GONAF stands for “Geophysical Observatory at the North Anatolian Fault”. Its main objective is to measure tectonic deformation transients (seismic and aseismic) along the overdue Marmara section of the North Anatolian Fault in northwestern Türkiye. It currently consists of eleven boreholes at seven locations south of Istanbul, which are equipped either with strings of short period geophones or strainmeters.

Strainmeter drawing

CAD model of Gaiacode’s borehole strainmeter

The new borehole observatory will be installed in two boreholes to be drilled next to each other near the northern shore of the Kepidağ Peninsula on the southern coast of the Marmara Sea. The majority of the Gaiacode instruments will be deployed in a 100 m deep borehole cased in steel. The pore pressure sensor will be cemented into a second, 50 m deep hole collocated with the first one. The analogue measurements from these instruments will all be transmitted to the well head, where they will be processed by a fleet of TAU digitizers. In addition, an optical fiber will be grouted behind the casing of the main hole to allow for future interrogations with DAS equipment.

Gaiacode will not only design and build the instruments, it is also responsible for the drilling of the boreholes and the installation of the equipment. Once installed, the observatory will be jointly operated by GFZ and AFAD. The installation is currently planned to begin this spring.

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References

  • Ref 1 USHER, M.J., BURCH, R.F. and GURALP, C.M., “Wide-band Feedback Seismometers”, 1979. Physics of the Earth and Planetary Interiors, 18: 38-50.
  • Ref 2 M,J, USHER and C.M. Guralp, “The design of miniature wideband seismometer” Geophys. J.R. ast. Soc. (1978)-55 (605-613) ,
  • Ref 3 GURALP, C.M., “The Design of a Three-component Borehole Seismometer”, 1980. Ph.D. Thesis, Univ of Reading.
  • Ref 4 GURALP C.M. Patent Application, No: 7909579 Filed: 19th March 1979 (declaration priority from Appln No: 10279/78 Filed: 15th March 1978) “Vertical Seismometer”.
  • Ref 5 GURALP C.M. United States Patent Application Number: 4,280.206 March 1979. SEISMOMETERS.
  • Ref 6 GURALP C.M. UK Patent Application GB 2-144-287-A. July 1983 Analog-to-digital converters for Seismometers. The National Research Development Corporation (UK)
  • Ref 7 GURALP C.M. UK Patent Application No. 1900719.4; Title: Infrasound Detector [M&S-IRN.FID4315516]