Joint analysis of b-value and apparent stress before the 2011 Mw9.0 Tohoku-Oki,Japan earthquake

• 作者: Yane Li Xuezhong Chen Lijuan Chen
• 来源期刊: 地震学报（英文版）
• 年，卷（期）: 2021,（4）
• 页码范围: 323-333
• 页数: 11页
• 语种: 英文
• DOI: 10.29382/eqs-2021-0036

摘要

Detecting tempo-spatial changes of crust stress associated with major earthquakes has implications for understanding earthquake seismogenic processes.We conducted a joint analysis of b-value and apparent stress in the source region before the March 11,2011 Mw9.0 Tohoku-Oki,Japan earthquake.Earthquakes that occurred between January 1,2000 and March 8,2011 were used to estimate b-values,while source parameters of events with magnitudes of Ms5.0-6.9 between January 1,1997 and March 8,2011 were used to calculate the apparent stresses.Our results show that the average b-value decreased steadily from 1.26 in 2003 to 0.99 before the Tohoku-Oki mainshock.This b-value decrease coincided with an increase in the apparent stress from 0.65 MPa to 1.64 MPa.Our results reveal a clear negative correlation between the decrease in b-value and increase in apparent stress,which lasted for approximately eight years prior to the 2011 mainshock.Additionally,spatial pattern results of the relative change in b-value show that the area associated with drastic b-value decreases(25％or greater)was concentrated near the 2011 mainshock epicenter.The joint analysis of b-value and apparent stress provides a promising method for detecting anomalies that could serve as potential indicators of large earthquakes.