Using the match-and-locate method to characterize foreshocks of the July 2019 M_(W)6.4 Ridgecrest,California earthquake  

作　　者：Min Liu Miao Zhang Hongyi Li 

机构地区：[1]Department of Earth and Environmental Sciences,Dalhousie University,Halifax,Nova Scotia B3H4R2,Canada [2]School of Geophysics and Information Technology,China University of Geosciences(Beijing),Beijing 100083,China [3]Shanghai Sheshan National Geophysical Observatory,Shanghai 201602,China

出　　处：《Earthquake Science》2022年第4期213-242,共30页地震学报（英文版）

基　　金：This work was co-supported by the National Natural Science Foundation of China(Nos.U1939203 and 41874063);China Earthquake Science Experiment project,China Earthquake Administration(No.2019CSES0113);the Fundamental Research Funds for the Central Universities of China(2-9-2019-172);Engineering Research Council of Canada Discovery Grant(RGPIN-2019-04297);the Ocean Frontier Institute International Postdoctoral Program.

摘　　要：The July 2019 M_(W)6.4 Ridgecrest,California earthquake and its distinct foreshocks were well recorded by local and regional stations,providing a great opportunity to characterize its foreshocks and investigate the nucleation mechanisms of the mainshock.In this study,we utilized the match-and-locate(M&L)method to build a high-precision foreshock catalog for this M_(W)6.4 earthquake.Compared with the sequential location methods(matched-filter+cross-correlation-based hypoDD),our new catalog contains more events with higher location accuracy.The M_(W)6.4 mainshock was preceded by 40 foreshocks within~2 h(on July 4,2019 from 15:35:29 to 17:32:52,UTC).Their spatiotemporal distribution revealed a complex seismogenic structure consisting of multiple fault strands,which were connected as a throughgoing fault by later foreshocks and eventually accommodated the 2019 M_(W)6.4 mainshock.To better understand the nucleation mechanism,we determined the rupture dimension of the largest M_(L)4.0 foreshock by calculating its initial rupture and centroid points using the M&L method.By estimating Coulomb stress change we suggested that the majority of foreshocks following the M_(L)4.0 event and M_(W)6.4 mainshock occurred within regions of increasing Coulomb stress,indicating that they were triggered by stress transfer.The nucleation process before the M_(L)4.0 event remains unclear due to the insufficient sampling rate of waveforms and small magnitude of events.Thus,our study demonstrates that the M&L method has superior detection and location ability,showing potential for studies that require high-precision location(e.g.,earthquake nucleation).

关 键 词：FORESHOCKS earthquake nucleation match-and-locate 

分 类 号：P315[天文地球—地震学]