Research Of Inversion And Model Building Based On Sumatra Wild-angle Data

The Sumatra subduction zone simeulue region is the area where the magnitude 9.2 earthquake in 2004 and magnitude 8.6 earthquake in 2005 happened.The geological structure and physical structure here is complicated.The mechanism of thrust slip and seismogenic needs further investigation.Besides,the velocity modeling is always one of the most important problems in seismic exploration.Therefore,it's very important to get the correct velocity structure which could specify the variation of crustal structure in this region and provide structural and physical properties.Based on the velocity model,the thrust fault and the seismic zone structure could be interpretated which mean great significance to understand the mechanism of thrust fault and seismogenic.In this paper,the velocity structure of a profile of simeulue island in Sumatra is inversed based on the wild-angle refraction traveltime data.Traveltime tomography can obtain good results because of the reliability of traveltime,the simple principle,mature development and so on.Therefore,this paper first deals with the processing and analysis of OBS data in the Sumatra zone.Then I picked the traveltime data,did ray-tracing and first-arrival tomography based on the first arrival data.After continuous iteration,the tomography velocity model of the region is obtained which could interpretate the velocity structure there.The full waveform inversion could utilize the multi-attribute information of seismic waves which contribute to the high resolution and precision but it also has requirements on input data and initial model.So on the basis of the tomography velocity model,a low-velocity anomaly was designed and added,then full-waveform inversion was conducted with forward-modeling data and got good results.