宁夏地区地壳新速度模型在地震定位中的应用
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摘要
本文利用有限差分法正演和遗传算法反演得到宁夏地区地壳新速度模型,再将该模型配置到MSDP软件的HYP2000定位方法中。选用宁夏地区2008年以来地震和爆破资料,从震中位置、深度及残差3个方面对新模型和原模型进行定位对比分析。结果表明:定位网内地震时,新模型得到的震中比原模型更接近断层,震群的深度也与断层分布更为吻合;运用新模型定位的爆破深度平均为2.8km,绝大多数不超过5km,落实爆破位置与定位结果差平均为水平2.4km、垂直2.6km,更符合大多为地表爆破的实际情况。进一步分析新模型定位的地震深度与宁夏地区地壳速度结构,发现地震发生在高速-低速转换地区。
In this paper,we develop a new crustal velocity model in Ningxia region,which is obtained by finite-difference forward modeling and genetic algorithm inversion.Configuring the model into HYP2000 method in MSDP software,we analyzed earthquakes and explosion data from the 3aspects of epicenter position,depth and residuals since 2008.The results show that epicenters located with new model are closer than older models to faults,and the depths of earthquake swarm located with the new model are also closer to faults.The average depth of explosions is 2.8km(only a few over 5km),and the horizontal difference between locating results and explossion sites is 2.4km,while vertical difference is 2.6km,which tally with the actual situation(explosions always take place on the ground).Furthermore,we found that earthquake depth is related to velocity structure in Ningxia area,and earthquakes always happened in high-low velocity transition zone.
引文
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