[M-IS04] Interdisciplinary studies on pre-earthquake processes

[MIS04-P09] Characteristics of Spatio-Temporal variation of b-values with statistical assessment and GNSS-based strain :
Application to the 2016 Kumamoto and the 2011 Tohoku earthquakes

*Katsumi Hattori¹, Zhong Yi², Chie Yoshino¹ (1.Department of Earth Sciences, Graduate School of Science, Chiba University, 2.Graduate School of Science and Engineering, Chiba University)

Keywords:b balue, assessment, GNSS-based strain

The frequency-magnitude distribution of earthquakes is expressed by the Gutenberg-Richter Law, in which a critical parameter is the b-value. The results of previous studies show that the b-value portrays not only the quantitation relationship between different earthquakes but also its magnitude negatively correlates with the regional stress level. In particular, the b-values show apparent precursor anomalies before some large earthquakes. But objectively judging their relevance to earthquakes is difficult. In order overcome this, we are developing evaluation methods that introduced the Akaike information criterion (AIC) and GNSS-based strain. Regarding the former, AIC, we investigate the difference dAIC between AIC over reference period and that of studied period. For the latter, GNSS-based strain, the correlation between monitoring strain anomalies and major local earthquakes has been verified in recent years. Therefore, this paper analyzes the characteristics of the b-value and GNSS-based strain network related to the 2016 Kumamoto and the 2011 Tohoku earthquakes to examine whether there are any anomalies in the occurrence of large earthquakes. The results will be shown in the presentation.