[M-IS09] Interdisciplinary studies on pre-earthquake processes

[MIS09-P06] New Developments in Crustal Deformation Research Using Pseudo-Strain Gauges with GNSS Data

*Yoichi NODA¹, Katsumi Hattori^2,3,4, Yukio Fujinawa⁵, Chie Yoshino² (1.Graduate School of Science and Engineering, Chiba University, 2.Graduate School of Science, Chiba University, 3.Center for Environmental Remote Sensing, Chiba University, 4.Research Institute of Disaster Medicine, Chiba University, 5.Organization for Development of Resilient Communities)

An investigation of the relationship between changes in the correlation coefficients of the orthogonal components of four-component borehole strainmeter data and earthquakes in China reported that the correlation coefficients, which are normally close to 1, decreased to 0.2 just before several significant earthquakes. In addition, a study of the relationship between network connectivity and earthquakes using correlation coefficients between stations of multiple borehole strainmeter data reported that anomalies tended to increase 20 days prior to earthquakes. In Japan, 67 strain gauges have been installed, but there is a limit to the number and regional bias. Therefore, using the GNSS continuous observation system (GEONET) deployed by the Geospatial Information Authority of Japan (GSI) at approximately 1,300 locations throughout Japan, we decided to construct a pseudo-strain gauge consisting of four GEONET observation points to index the amount of crustal deformation. Then, we investigated the relationship between the network connectivity calculated from the correlation coefficients among the pseudo-strainmeter stations and earthquakes. In this report, we report the results of our attempts to extract variations before and after the 2016 Kumamoto earthquake (Mw 7.0), the 2011 off the Pacific coast of Tohoku earthquake (Mw 9.0), and the 2024 Noto Peninsula earthquake (Mw 7.5).