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Stable levelling and locking methods applicable for borehole very broad band

Stable levelling and locking methods applicable for borehole very broad band seismic sensors including tilt meters. presented at SUPERSITES COORDINATION WORKSHOP Monday 10 June 2013 Cansun Guralp. Why borehole instruments?. Reduce the seismic back ground noise

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Stable levelling and locking methods applicable for borehole very broad band

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  1. Stable levelling and locking methods applicable for borehole very broad band seismic sensors including tilt meters presented at SUPERSITES COORDINATION WORKSHOP Monday 10 June 2013 Cansun Guralp

  2. Why borehole instruments? • Reduce the seismic back ground noise • Facilitates to record seismic data under reduced noise conditions in the long period and short period seismic bands thereby improving: • signal‐to‐noise ratio • magnitude detection threshold • precision of hypocentre determination • Get closer to the source of earthquakes • Allows to broaden the frequency band of the recorded seismic signals including high frequency components. • Provide multidisciplinary seismic observatory • Strong motion • Broad band 360 second period to 200 Hz, with single jaw hole lock. • Two axis tilt meter with three jaw hole-lock • High resolution Temperature sensor • Strain gauge, cemented

  3. CMG-3TB Seismometer • Deployment options for installation: • with a hole-lock • Single arm hole lock with skids • Three jaw hole lock • or with bishops hat orientation system • in SAND packed borehole, without a hole lock • Cemented sensor • in a cased borehole • in an un-cased borehole Other features: • Options such as Horizontal component orientation • provided with integrated accelerometer

  4. CMG-3TB: example of some Global Installations USA Norway Russia UK Belgium Switzerland Kazakhstan South Korea Turkey Turkmenistan USA Japan China Tunisia Iran Pakistan Israel Saudi Arabia Taiwan Mexico Senegal Bangladesh Niger Oman Montserrat Peru Brazil Australia New Zealand Antarctica

  5. CMG-3TB Seismometer With three jaw hole-lock

  6. Borehole Sensor with three jaw hole lock Some examples of borehole seismometer packages

  7. Borehole Sensor with three jaw hole lock Some examples of borehole seismometer packages

  8. Closer to source I Joint experiment: 3T/5T borehole sensor + DM24 at >1000 m depth, optical data transmission to well head

  9. Closer to source II Our sensor deployed at 1039.50 m in Pilot Hole

  10. Example of typical down-hole recording: Microearthquakesnot observed on surface, most common type of microearthquakeobserved: S-P time: 0.74 sec hypocentraldistance between 4-5 km

  11. Earth Tides

  12. Pinnacle tiltmeter (2007) some peculiarities to be resolved: 1. ultra long period (4-8 min) noise

  13. CMG-3TB Case Studies Data from 4 different sensor installations at the same location, high frequency performance of 3TB is clearly demonstrated Presented at the IRIS Broad-Band Instrumentation Workshop; Lake Tahoe, Mar 24-26, 2004

  14. CMG-3TBD Seismometer • Titanium case with three component broad band sensor 360 sec to 50 Hz. • ± 5 degrees of tilt compensation. • 4 Channel 24 bit digitiser with time synchronisation. • Mass position outputs used as tilt data and compared to a very high resolution tilt sensor 5*10-9 radian. • Deployed with cement at 3000 meter depth. 2400 meters sea water and 600 meters of sea bottom borehole.

  15. CMG-3TB Seismometer

  16. Reduce the seismic noise • Facilitates to record seismic data under reduced noise conditions in the long period and short period seismic bands thereby improving: • signal‐to‐noise ratio • magnitude detection threshold • precision of hypocentre determination • Get closer to the source of earthquakes • Allows to broaden the frequency band of the recorded seismic signals including high frequency components. • Provide multidisciplinary seismic station • Strong motion • Broad band 360 second period to 200 Hz, with single jaw hole lock. • Two axis tilt meter with three jaw hole-lock • Hydrophone • High resolution Temperature sensor • Strain gauge, cemented

  17. Thank You !

  18. CMG-3TB Case Studies • Matsushiro, Japan. • Installed April 2008 • Deployed at a depth of 700m • CMG-3TB very broadband (VBB) velocity sensor with response from 360s to 100Hz; • CMG-5TB strong motion sensor with response from DC to 200Hz; • CMG-DM24mk3 7-channel 24-bit downhole digitiser with serial to optical converter; • Single jaw hole lock (pressure compensated).

  19. CMG-3TB Case Studies (Belgium) Above a Magnitude 6.4 in Crete recorded on all four sensors

  20. CMG-3TB Case Studies • Nuclear Explosion Treaty Monitoring

  21. CMG-3TB Case Studies • The above sensors feature a bishop hat orientation module allowing them to use the original KS-54000 and KS-36000 holelock mechanisms retaining the same physical orientation in the Boreholes

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