Time-lapse slip variation associated with a medium-size earthquake revealed by "repeating" micro-earthquakes: the 1999 Xiuyan, Liaoning, <i>M</i><sub>S</sub> = 5.4 earthquake

Abstract

We obtained the time-lapse cumulative slip before and after the 29 November 1999, Xiuyan, Liaoning, China, <i>M</i>_s = 5.4 earthquake by using "repeating events" defined by waveform cross-correlation. We used the seismic waveform data from the Liaoning Regional Seismograph Network from June 1999 to December 2006. Two "multiplets" located near the seismogenic fault of the 1999 Xiuyan earthquake and the 4 February 1975, Haicheng <i>M</i>_s = 7.3 earthquake, respectively, were investigated. For the "multiplet" that occurred before and after the 1999 Xiuyan earthquake, apparent pre-shock accelerating-like slip behavior, clear immediate-post-seismic change, and relaxation-like post-seismic change can be observed. As a comparison, for the "multiplet" near the 1975 Haicheng earthquake which occurred a quarter century ago, the cumulative slip appears linear with a much smaller slip rate

Fault structures of the Haichenghe fault zone in Liaoning, China from high-precision location based on dense array observation

“…Pre-acceleration and immediate-post slip associated to the M 5.4 Xiuyan earthquake were found on the Xiuyan portion by assessing the accumulative slip based on the repeating earthquake magnitudes, indicating the preparation and the relaxation process of the M 5.4 Xiuyan earthquake. In their study, only larger-magnitude repeating earthquakes, that is M ≥ 3.0 in Schaff and Richards (2004) and M L ≥ 1.6 in Li et al (2011), were discovered due to the sparse station coverage.…”

“…On the Haichenghe fault, Schaff and Richards (2004) discovered a multiplet in Xiuyan containing 28 repeaters by processing waveforms of about 14000 events from the networks in and surrounding China for 1985 to 2000. Li et al (2011) used seismic data before and after the M 5.4 29 November 1999 Xiuyan earthquake from 15 broadband or short-period stations in Liaoning and identi ed 2 multiplets, each locating at Xiuyan and Yingkou, which is to the SW of Haicheng, respectively. Pre-acceleration and immediate-post slip associated to the M 5.4 Xiuyan earthquake were found on the Xiuyan portion by assessing the accumulative slip based on the repeating earthquake magnitudes, indicating the preparation and the relaxation process of the M 5.4 Xiuyan earthquake.…”