Research On Seismic Sequence Completeness Based On Template Matching Method And The Double-difference Location

The earthquake catalog is an important basic data for regional seis mic activity research such as seismic hazard analysis and the seismic geology research.It provides a data foundation for studying seismicity,earthquake disasters,and risk assessment.Seismic network monitoring capabilities,seismic positioning technology,artificial experiential gaps,and noise interference all contribute to the non-uniformity and discontinuity of seismic catalogs.Therefore,the quality of seismic catalogs used for analysis is very important.The completeness of the earthquake catalog and the accuracy of the source parameters will affect the scientificity and reliability of follow-up research.After a strong earthquake occurs or when an earthquake swarm moves,a large number of earthquakes will occur in a short time.The waveforms of different seismic events overlap each other.It is more difficult to identify earthquakes with smaller magnitudes based on observed phenomena.In this case,the current template matching method based on cross-correlation technology is an effective method for detecting missing events in the case of low SNR and has been widely used at home and abroad.The research work of micro-seismic events has a wide range of applications.It plays a decisive role in the research of induced earthquake monitoring,low-frequency seismic monitoring of terrestrial vibration,and earthquake warning.The automatic identification of microseismic events and the automatic pick-up of seismic phases are the basis for later microseismic data processing,including seismic location,seismic imaging,and inversion of focal mechanism.This paper briefly analyzes the principle origin and general classification application of various types of seismic event automatic identification and phase picking methods.It mainly introduces three types of me thods: The first type is based on the amplitude(energy)criteria of long and short time window ratio,the source Additional methods such as scanning and stacking event recognition and seismic phase picking;second,event recognition based on waveform cross-correlation technology;and third,blind search based on waveform autocorrelation.In the research process of this paper,according to the advantages and disadvantages of the three methods of automatic identification of seismic events,we chosen the second method,the template matching method.Two major earthquakes around gansu province,Ms6.4 menyuan,Q inghai,on January 21,2016,and M7.0,jiuzhaigou,Sichuan,on August 8,2017,were selected as study examples in this paper.The final result for MenYuan earthquake aftershock sequence of the communist party of C hina detected 430 missing earthquakes and 1053 missing earthquakes detected in jiuzhaigou aftershock sequence of the communist party of China earthquake,after detection of the earthquake catalogue is relatively more perfect network directory.To locate detected seismic events,and methods of extracting seismic phase when the waveform cross-correlation for detecting all events to pick up,the P and S seismic phase recycled Hyposat locator for absolute positioning processing.Finally using the double-difference location method for detecting after two earthquake cases the aftershocks,get a more accurate positioning results,for the next two earthquake cases provide more references for scientific research.