[M-AG37] CTBT IMS Technologies for Detecting Nuclear Explosion and Their Applications to Earth Science

[MAG37-P02] Interpretations of hydrodynamic pressure observations during an earthquake

*Hiroyuki Matsumoto¹, Hiroaki Kajikawa², Keisuke Ariyoshi¹, Narumi Takahashi^1,3, Eiichiro Araki¹ (1.Japan Agency for Marine-Earth Science and Technology, 2.National Institute of Advanced Industrial Science and Technology, 3.National Research Institute for Earth Science and Disaster Resilience)

The series of hydrodynamic pressure dataset recorded by the experiment and the in-situ observation at the seafloor during the far-field earthquake are examined. A large earthquake (Mw7.8) occurred off the Aleutian Islands while hydrostatic pressure produced by the dead-weight tester was applied to some different typed pressure transducers; one is the quartz resonant pressure transducer and the other is silicon resonant pressure transducer. All pressure transducers were set into the 2-degreeC oil chamber and pressurized with 20 MPa, by which the pressure transducers could be regarded as they were at approximately 2000 meter water depth. Ambient ground motion was also monitored by a broadband seismometer during the present experiment. The initial seismic wave associated with the Aleutian Islands earthquake was recorded by the broadband seismometer at 9 min after the earthquake, followed by the Rayleigh wave which was predominant at the laboratory. It is worthwhile noting that hydrodynamic pressure fluctuations were identified for all pressurized transducers, which was attributable to vertical movement of the deadweight. Comparing the experimental recording with the in-situ observation by the DONET pressure sensor deployed at 2000 meter, pressure amplitudes are fairly coincident each other at a frequency range around 0.04 Hz. Experimental observation is larger than the in-situ observation at a low frequency range below 0.02 Hz, which may be attributed to the ambient pressure change. Our experiment suggests that the silicon resonant pressure transducer shows less sensitivity than the quartz resonant pressure transducer at a high frequency range over 0.1 Hz.