甘肃地区一维速度模型计算研究

Study on the One Dimensional Velocity Model in Gansu Area

摘要:

采用2009年1月1日-2014年6月甘肃省境内所有地震的震相数据，分类拟合计算该地区一维速度模型，计算结果显示，利用少量震级较大地震数据来拟合的速度结果近似于用所有地震拟合结果。拟合得出新模型初步结果后，再从所有地震资料中选定台站包围好、震相标识规范的142个地震，利用Hyposat定位方法来计算莫霍面深度，参考其他模型的莫霍面深度，综合分析后在一定的扰动范围内通过Hyposat批处理程序进行迭代定位，对8 640次计算模型做残差对比，最终选取残差最小模型作为新模型，此模型除部分参数有较小的差别外与甘青模型基本一致。

Abstract:

This paper aims to work out a one-dimensional velocity model for Gansu area with a large amount of seismic data gained by the digital measuring seismic technology. Specifically, this study does classification and fitting calculation to get a one-dimensional velocity model, using the data of seismic phase of all the earthquakes happened in Gansu province from the period between January, 2009 to June, 2016. The purpose of classification is to show the influence of the results of fitting calculation on the seismic data, and the results show that fitting of a few closely approximates of all the earthquakes. Because there are many recording stations for major earthquakes and their epicentral distances are well-distributed, major earthquakes are chosen to be the objects of the study. On the basis of the preliminary results of the new model through the fitting calculation, we relocated 142 earthquakes that azimuths are well-distributed and seismic phases are clear by Hyposat program to calculated the depth of Moho surface. We also reference other models such as Ganqing Model,Crust1.0 and the averaging model of Gansu and the Acceptance Function are applied as references. After this calculation, a Hyposat batch processing of iterative localization is done within the scope of disturbance gained from the comprehensive calculation. Finally, based on the 8640 computations of the model and several residue contrasts, a model with minimum residue has been chosen as the new model. The newly-made model is basically consistent with the Ganqing Model, with just a few parameters different. The new model is applied to the location of 142 earthquakes, relative to Ganqing model the average residual reduced 0.05. The model is a large range of average results that cannot be applied to all earthquakes. According to the selected 142 earthquake distribution location weight, the model is more suitable for the southeast region of Gansu. In order to test the availability of the model, the model will be used in the daily cataloging process of Gansu seismic network, calculation results are obtained by a huge amount of data, the inspection also need plenty of seismic data. At present, the Gansu seismic network has used the Ganqing model and the new model at the same time, and make statistical two model's positioning accuracy in different region and with different magnitude.