Application Of Seismic Tomography In Sumatra

The most important problem of seismic exploration is how to obtain the best underground structure,and the underground velocity information is undoubtedly an important parameter to reflect the underground structure.Therefore,velocity modeling has always been one of the most important problems in seismic exploration.Therefore,it is particularly important to obtain the correct velocity structure.Based on the artificial source wide angle seismic data collected in the area of Nias island of Sumatra,this paper processes the original data,picks the first arrival travel time data and select the best inversion parameters at the same time.By the two kinds of program,FAST and JIVE3 D,this paper inverse the data.As the result,we acquire the best velocity model,and get the more accurate geological structure in this area.At the same time,according to the geological structure and the two earthquakes phenomenon near the island of Nias,we interperate the geological structure.There is a basic subduction zone,which is composed of oceanic subduction plates,trench slopes,and accretive sediments.This area also has island arc,arc basin,"backstop" and other geological structures.Moreover,the sedimentary volume changes of the wedge-shape block in the accretionary sedimentary layer formed a seismic fracture boundary,which led to the phenomenon that the two earthquakes caused the directional propagation of the earthquake fracture.At the same time,the volume change of the wedge-shape block caused the settlement of the islands of Nias and Batu to a certain extent.