[J09-3] Geodesy and seismology general contributions III

[J09-3-03] Tracking of water level of dam reservoir by using a broadband seismometer

^○Kazunari Nawa¹, Takeshi Kimura² (1.AIST, Tsukuba, Japan, 2.NIED, Tsukuba, Japan)

We found distinctive incessant monochromatic oscillations with a frequency around 10 mHz by analyzing STS-2 broadband seismometer data of the F-net IGK station at Ishigakijima, Okinawa, Japan. The possible origin of oscillation is seiche (water level oscillation) of dam reservoir in the vicinity of the seismic station. We show the frequency variations of the mode for five years (2012-2016) based on STS-2 seismograms. Observed frequency variations are in good agreement with water level change of dam reservoir compiled from dam observation daily reports. And we discuss implications for long-term monitoring hydrological condition and/or the state of the seismometer system.