Imaging The Rupture Process Of 2001 Kunlun Mountains Mw7.8 Earthquake Using Backprojection Method Combining The Aftershock Information

It is of great significance to study the earthquake rupture process for understanding the mechanism of earthquakes,the geological structure of the earthquake zone and organizing the earthquake relief work actively and effectively.Back-projection method is currently one of the main methods to study the earthquake rupture process.However,for the earthquakes with large fault rupture scale,there are some errors in the time correction with a single epicenter.When the rupture scale is large,the earth model differs greatly from other locations and the epicenter,and there is a large error in the result of the approximate correction of the epicenter value.Therefore,this paper uses the method of multi-epicenter correction to reduce the impact of this difference and improve the accuracy of imaging results.In this paper,we use the rupture process of the Kunlun Mountains earthquake in 2001 to analyze the effect of this method on the imaging results.Considering the size of the earthquake zone,the strength of the earthquake magnitude and the quality of the record,We chose a 5.4 Mw aftershock,using its epicenter and the main shock epicenter to divide the earthquake area,and then based on the traditional back projection method,the two earthquake zones were corrected respectively in time correction.We obtained imaging results and energy distributions using different methods.By comparing the results,we analyzed the effect of using the multi-epicenter correction on the imaging results.The results show that using a single epicenter correction,the imaging results in the smaller range from the epicenter,in the energy release and the imaging of the rupture are more in line with the actual situation of rupture,but in the range farther from the epicenter,the energy convergence is not good and the location of the rupture deviates greatly.The overall energy distribution and rupture zone also have large deviations.While the result of using the co-correction between the main shock and the aftershock epicenter,the two epicenters have been divided into two regions so that the potential focal points in the entire earthquake region are not particularly large from their respective epicenter,are more consistent with the actual fault rupture,both in the energy release and the imaging of the rupture.Especially in the former earthquake zone that far away from the single epicenter,the imaging result is obviously improved.In summary,using multiple earthquakes to divide the seismic zones and jointly carrying out the time difference correction back projection method can improve the imaging accuracy of the earthquake rupture process effectively compared with the back-projection method that uses single epicenter in time correction.