Analysis Of The Wenchuan Earthquake Source Process

May12,2008, Mw7.9Wenchuan earthquake occurred in the eastern margin ofthe Tibetan Plateau Longmen Shan fault zone. The earthquake in western Chinaproduced throughout a wide range of strongly felt. After a major earthquake, studyand understand the source process is the study of earthquakes earthquakemechanism is an important work, which is to determine the source of the corerupture velocity, duration, and temporal and spatial distribution of radiation energyand rupture model. In order to achieve the shortest possible time with the highestresolution possible to determine the details of earthquake rupture process, this paperwe use teleseismic P-wave radiation energy back-projection method for theearthquake were studied. The method developed in recent years is a rapid methodfor the determination of seismic counter-radiation energy distribution and changesin its traditional teleseismic body wave tomographic inversion limited comparedwith the greater potential and develop faster.Study, we collected from the IRIS DMC teleseismic P-wave verticalcomponent waveform recording epicentral distance range in Europe and NorthAmerica, two arrays of30°-95°recorded, of which the number of stations inEurope was87(waveform recording87), the waveform record length used is650S.IRIS uses the same source parameters provided in the100°E-107°E, within28°N-34°N range to0.1°×0.1°grid will be split focal area, as well as the first to useIASPEI91velocity model the method to calculate the geometric ray source theorywhen walking in the epicenter (P-wave first arrival) carried moveout. Since thedifference between the actual waveform correction with a three-dimensionalgeological structure between the theoretical model of the resulting alignment is notvery good, we intercept the P wave to the beginning five seconds before and10seconds after the recording waveform in the study, the use of waveformcross-correlation to calculate the " cross-correlation lag " and corrected.Then, we assume that each mesh node are likely to be the source location,reuse IASPEI91model to calculate each " node epicenter " to the theory of eachstation ’s travel time, go through the time difference correction " node epicenter " and the actual epicenter of the " theory " get selected array for each grid node theoryrecorded waveforms. Thereafter, the velocity of each array by using the recordingwaveform superimposed calculate each " source node " of the release of the seismicwave is received by the array to the total energy versus time curve. Energydistribution obtained according to the energy value for the same period of eachoverlay node over time the snapshot and the release process.