Analysis of the Seismicity of Two Types of Earthquake Sequences in Yanjin,Yunnan
Based on the catalogue and waveforms of moderate-and small-earthquakes occurring in Yanjin area during September 2020 to January 2021,we use the Match and Locate(M&L)method to detect and locate weak e-vents.A total of 1 340 events are detected by the M&L method,which are about 6.7 times the number of events listed in the Yunnan Seismic Networks Catalogue.We then obtain refined hypocenters of 351 detected earthquakes by simultaneously using P and S travel times and waveform cross-correlation data in the double-difference relocation al-gorithm.We also investigate the spatial-temporal characteristics of the detected earthquakes after double-difference relocation.Our results indicate that the moderate-and small-earthquakes occurring in Yanjin area during September 2020 to January 2021 could be categorized as two different types earthquake sequences:the ML3.9 swarm main-shock type,and the ML5.2 isolated earthquake.These two types of earthquake sequences occurred along two differ-ent faults with different strike and dip angles.The ML3.9 swam sequence occurred on the Yanjin-Junlian fault with a strike of NNW direction and dip angle of about 75°,and the ML5.2 isolated-sequence occurred on a blind fault with a strike of near NS direction and a dip angle of about 50.
Yanjin areaearthquake detectionthe Match and Locate methodthe double-difference reloca-tionearthquake sequenceseismogenic structure
万方数据
维普
