[S-GD01] Geodesy and Global Geodetic Observing System

[SGD01-09] Vertical Movements of GEONET sites in Niigata region (Part 2)

*Seiichi Shimada¹, Yuka Ito¹, Masaatsu Aichi¹, Takemu Seki², Tomochika Tokunaga¹ (1.Graduate School of Frontier Sciences, The University of Tokyo, 2.Department of Systems Innovation, Faculty of Engineering, The University of Tokyo)

Keywords:Niigata region, Vertical movements, GNSS, GEONET

We have present on the vertical movements in Niigata region, at the 2018 Meeting of the Geodetic Society of Japan titled “Vertical movements of GEONET sites in Niigata region” and at the 2019 Meeting of the Geodetic Society of Japan titled “The characteristics of the vertical movements in Niigata region caused by the groundwater usage for snow melting and the quaternary paleoenvironment”, and reported on the vertical variations of uplift and subsidence due to the post-seismic crustal deformations of the 2011 Great East Japan Earthquake, on annual variations mainly due to the usage of groundwater for snow melting, on the secular ground subsidence due to the usage of groundwater, which varies depending on the observation sites, and on the possibility that the difference of the vertical variations among the observation sites caused by the pumping groundwater for snow melting depends on the geology of the aquifer and the layer above it. In this presentation we report that the subsequent studies have revealed that a subsidence may also be observed caused by the pumping of groundwater for the agriculture usage in summer in some of the observation sites and years. Moreover, we will also present the characteristics of the significant land subsidence that has observed by the groundwater pumping for the usage of the melting of heavy snowfall during the period of December 2020 and February 2021, and that has not been seen in the last 10 years, comparing with the subsidence in winter so far.