第59回統計地震学セミナー / The 59th Statistical Seismology Seminar

Date&Time
2016年7月19日(火)
/ 19 July, 2016 (Tuesday) 16:00 – 17:00

Admission Free,No Booking Necessary

Place
統計数理研究所 セミナー室3 (D312-A)
/ Seminar room 3 (D312-A) @ The Institute of Statistical Mathematics
区切り線
Speaker
Prof. Yuh-Ing Chen
(Institute of Statistics, National Central University, Taiwan, ROC)
Title
Statistical evaluation of short-term hazard of earthquakes after 1999 M 7.3 Chi-Chi shock in Taiwan
Abstract
The temporal-spatial hazard of the earthquakes in a continental region of Taiwan after the 1999 September 21 MW =7.7 Chi-Chi shock is investigated.  The Reasenberg-Jones (RJ) model (Reasenberg and Jones, 1989) that combines the frequency-magnitude distribution (Gutenberg and Richter, 1944) and time-decaying occurrence rate (Utsu et al., 1995) is conventionally employed for assessing the earthquake hazard after a large shock (Wiemer, 2000).  However, it is found that the b values in the frequency-magnitude distribution of the earthquakes in the study region dramatically decreased from background values after the Chi-Chi shock, and then gradually increased up.  The observation of a time-dependent distribution of magnitude motivated us to propose a modified RJ model (MRJ) to assess the earthquake hazard (Chen et al. 2015).  To incorporate the possible impact of previous large earthquakes on the following ones, a simplified epidemic-type aftershock sequence (ETAS) model (Ogata, 1988, Ogata and Zhunag, 2006) is further considered.  A modified ETAS (METAS) model that combines the simplified ETAS model and the time-dependent distribution of magnitude is then suggested for the hazard evaluation.  The MRJ and METAS models are further separately used to make one-day forecast of large earthquakes in the study region.  To depict the potential rupture area for future large earthquakes, we also develop the space-time MRJ and METAS models and construct the corresponding relative hazard (RH) maps.  The Receiver Operating Characteristics (ROC) curves (Swets, 1988) demonstrate that the RH map based on the MRJ model is as good as the one based on the METAS model for exploring the spatial hazard of earthquakes in a short time after the Chi-Chi shock.