Characteristics of wave velocity ratio at single seismic station before December 18,2023,Jishishan Ms 6.2 earthquake
Based on the seismic phase observation reports produced by Gansu and its adjacent provincial networks from January 2015 to December 2023,this paper analyzes the variation of single-station wave velocity ratio in the vicinity of the epicenter before the Jishishan Ms 6.2 earthquake on December 18,2023,using the Wadati method of single-station and multi-earthquake.The results show that the wave velocity ratio of MIH and LZH stations exhibited different forms of low-value anomalies before the earthquake,while the wave velocity ratio of BYT,WYT,HZT,and MXT stations remained relatively stable before the earthquake.Compared with MIH,LZH,and BYT stations located north of the epicenter,WYT,HZT,and MXT stations located south of the epicenter have significantly higher average wave velocity ratios.Based on comprehensive analysis,we think that the low-value anomaly of wave velocity ratio at MIH and LZH stations has an important reference value for determining the possible existence of seismogenic bodies in the north and northeast directions before the Jishishan Ms 6.2 earthquake.In addition,the velocity ratio of a single station near the epicenter has a distribution characteristic of being higher in the south and lower in the north.
Jishishan Ms 6.2 earthquakeWadati method of single-station and multi-earthquakewave velocity ratiobefore earthquakevariation characteristics
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