Research Of Repeat Earthquake In Xiaojiang Fault

The concept of repeated earthquakes was proposed in early years.In1980,Mueller and Geller found the repeat of small earthquake in San Andreas fault,and propose a concept of Repeating Earthquakes.They believe that rupture of isolated asperities loaded by surrounding creep lead to small repeating earthquakes.For now,the definition of repeating earthquakes is controversial,but almost all researchers require repeating earthquakes have very similar waves,and how to recognize repeating earthquake become the aim of different researchers.The detection of repeated earthquakes mainly relies on the calculation of correlation coefficient function in the software SAC(Seismic Analysis Code),this is an analytical method developed based on the waveform cross correlation technique in digital seismology.By calculating the correlation coefficient,the similarity degree of two or more earthquakes' waveform can be distinguished,and then,a threshold is set to define earthquakes with a certain correlation coefficient as repeated earthquakes.In this paper,the writer used the method of low-pass band filtering with frequency domain zero padding and time domain interpolation to recognize seven groups repeating earthquakes in the range of 3.5-5 in the around of Xiaojiang fault in 2009-2020,with the condition of lesser station density lower pick-up frequency of seismic wave,it belongs to the broad sense of repeating earthquakes.