[G02-P] Poster

[G02-P-05] Local hydrological disturbances on gravity revealed by simultaneous observation with a gPhone and a superconducting gravimeter

^○Kazuma Mochizuki^{1, 3}, Kazunari Nawa¹, Yuichi Imanishi² (1.Geological Survey of Japan, AIST, Tsukuba, Japan, 2.The University of Tokyo, Tokyo, Japan, 3.Shizuoka University, Shizuoka, Japan)

In August 2016, continuous gravity observation with a gPhone gravimeter (# 133) was started at the F-net IGK (Ishigaki) station of the National Research Institute for Earth Science and Disaster Resilience (NIED), in order to supplement the superconducting gravimeter CT36 at the VERA Ishigakijima station of the National Astronomical Observatory of Japan. The F-net station is about 900 meters away from the VERA station. In spite of some initial problems, the gPhone gravimeter has been producing high-quality records since late November, 2016, thanks to the stable condition inside the observation vault free from the effects of solar radiation and ambient temperature changes. From the comparison of two month long data, it is shown that the gravity records from the two gravimeters are in agreement to within 5 microgals. The small difference in the observed gravity is highly likely to reflect the different responses of gravity to local precipitation at the two sites. Detailed investigation of this signal in comparison with meteorological data will be useful for precise modeling and correction of hydrological disturbances on gravity, and then retrieving deep underground signals (i.e. slow slip events).