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Recording crustal tilt with the new NSWT in Lohja, Finland

Recording crustal tilt with the new NSWT in Lohja, Finland. Hannu Ruotsalainen Finnish Geodetic Institute. Content. Some principles of interferometrical watertube tiltmeter Construction and instrumentation of the new NSWT First recordings Crustal loading of Gulf of Finland.

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Recording crustal tilt with the new NSWT in Lohja, Finland

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  1. Recording crustal tilt with the new NSWT in Lohja, Finland Hannu Ruotsalainen Finnish Geodetic Institute

  2. Content • Some principles of interferometrical watertube tiltmeter • Construction and instrumentation of the new NSWT • First recordings • Crustal loading of Gulf of Finland

  3. Michelson&Gale WT 1914-1919

  4. Kukkamäki 1 km landuplift tiltmeter plan in1965

  5. Kääriäinen NS & EW WT in Lohja 1977-1998

  6. Ruotsalainen design

  7. Prototype in FGI lab

  8. Fizeau level interferometer

  9. New 50.4 m long NSWT in Lohja mine

  10. 50.4 m long NSWT

  11. Modernization during 2007-2008 • Modular stainless steel tube & junctions laying on bedrock surface adjusted with concrete plates and triangle shape bricks to prepare stability • Possible leakages of 50.4 m tube line tested with high (~3 atm) air pressure • Pots plated inside with teflon to avoid fluid friction against pot walls • New 2 mW HeNe-lasers and collimators • Computer recording carried out from 200 & 250 meters away from interferometers by using fiberoptic links .

  12. Earthquakes and seismics in phase recording

  13. NSWT recording 2/2008

  14. Loading of Gulf of Finland

  15. Residual of old NSWT and TG record of Hanko in 10/1992

  16. Future • First tidal tilt analyse after 3 month of data • Comparison of non-tidal residual with Baltic Sea loading • Internet connection is planned to be built between Lohja and FGI to control recordings and download data and to use NTP timing of computers.

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