吳逸民Wu, Yih-Min臺灣大學:地質科學研究所阮國強Nguyen, Quoc-CuongQuoc-CuongNguyen2010-05-112018-06-282010-05-112018-06-282009U0001-0901200905522500http://ntur.lib.ntu.edu.tw//handle/246246/182902ABSTRACTayered velocity model is important information for seismological study. Actually is being used the three layers model in Vietnam region but it is too simple because of owing to the lack of condition of data in the earthquake catalogues. Thus, it is necessary to build up a good-layered model for earthquake monitoring in Vietnam.imultaneous determination of thicknesses and velocities of a layered model is a non-linear problem. Genetic algorithm is one of the methods to solve non-linear problem. In this study, we have tried to apply this method to determine a layered model for Red River.y results were obtained by separating the new 1D model into 7-8 layers. The first one presents a velocity of 4.3 km/s, instead of 5.8 km/s in the fore studies. For a deeper layer from 0.6 km to 7.6 km P wave velocity becomes larger 5.4 km/s – 5.8 km/s. Thus, I suggest that above the base rocks, there is a layer of crack rocks situating at the depth from 0.6 to 7.6 km. This ideal from new model seems agreeable with territory and tectonic of Vietnam. According to Cao et al. (2000), Nguyen et al. (2004) Conrad layer when depth changes from 17 km to 23 km and P wave velocity changes from 6.1 to 6.7 km/s. Finally when the depth of Moho surface changes from 24 to 35 km the P wave velocity also changes from 7.6 -8.1 km/s.CONTENTCKNOWLEDGMENTS......................................................................iiibstract....................................................................................................ivist of Figures...........................................................................................vist of Tables..........................................................................................viii. Introduction........................................................................1 . Characteristic of Red River Fault Zone and seismological network.......................................................................................3 2.1 Characteristic of Red River Fault.........................................3 2.2 Seismological network of Vietnam.......................................9 2.3 Seismicity of Northern Vietnam.........................................14 2.4 Data.....................................................................................18. Methodology.........................................................................19 .1 Principle of initial data preprocessing....................19.2 Theoretical basic of Genetic Algorithm....................213.2.1 Theoretical of Genetic Algorithm................................213.2.2 GA program and its parameters................................24 . Results...................................................................................28 4.1 Results of average 1D Velocity model.................................28 4.2 Results of 1D velocity structure after relocate....................34. Discussions............................................................................41 5.1 Single station results and distribution of Stations..............41 5.2 Synthetic test in further study............................................44. Conclusion...........................................................................45eferences...............................................................................48application/pdf2199600 bytesapplication/pdfen-USRed River Fault ZoneVelocity structureGenetic algorithmthesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/182902/1/ntu-98-R95224217-1.pdf