基于特大地震发生率的川滇地区地震危险性预测新模型  

A new prediction model of seismic hazard for the Sichuan-Yunnan region based on the occurrence rate of large earthquakes

作　　者：程佳 徐锡伟 陈桂华[2] CHENG Jia;XU XiWei;CHEN GuiHua(Institute of Crustal Dynamics,China Earthquake Administration,Beijing 100085,China;Key laboratory of Active Tectonics&Volcano,Institute of Geology,China Earthquake Administration,Beijing 100029,China)

机构地区：[1]中国地震局地壳应力研究所,北京100085 [2]中国地震局地质研究所,北京100029

出　　处：《地球物理学报》2020年第3期1170-1182,共13页Chinese Journal of Geophysics

基　　金：国家重点研发项目（2018YFC1504201）;中央级公益性科研院所基本科研业务专项（ZDJ2018-22）;国家自然科学基金重大专项（41941016）共同资助

摘　　要：川滇地区是我国地震危险性较高的地区之一.本文基于对特大强震的风险性考虑,使用全球地震模型OpenQuake软件,建立了川滇地区地震危险性预测新模型.首先根据构造特征划分多个震源分区,并整理出这些震源分区内断层活动特征与滑动速率;基于震源分区和断层模型,使用GPS应变率转换成的锥形古登堡-里克特关系作为整个区域的地震积累率,并允许超过历史最大震级的特大地震的出现,结合活动断层滑动速率所积累的地震发生率,给出震源分区内断层地震源和背景地震源的地震发生率的比率分配关系;在活动断层分段上,保留了大型断裂或其主要部分,没有根据小的阶区来对断层进行详细分段,以便分配特大地震发生率;并使用地震率平滑方法分配背景地震发生率.最后在OpenQuake中加入地震动预测方程,计算出了川滇地区的PGA分布图,为区域地震危险性提供科学依据.Sichuan-Yunnan is one of the regions with high seismic hazard and risk in China.To facilitate prediction and prevention of the catastrophic large earthquakes,we establish a new model of seismic hazard analysis for the Sichuan-Yunnan region using the OpenQuake software.First,we divide the region into 11 different seismic source zones according to the contemporary tectonic deformation characters.We also collect the slip rates of the major faults in each zone.Then,we use the tapered Gutenberg-Richter relationship to transfer the GPS strain rate into the predicted seismicity rate for each seismic source Zone,including the earthquakes with magnitude larger than historical events.We also transfer the slip rate of the fault into seismicity accumulation rate.According to the ratio between the seismicity rate for each seismic source zone and on the faults in the zone,we distribute the predicted earthquake rates for each magnitude bin onto the fault sources and the background seismicity.Our procedure considers the possibility of the earthquakes larger than the maximum magnitude in the historical catalog.To distribute these large earthquakes,we do not divide the faults into segments with the small fault steps,especially for the major active faults.For the background seismicity rate,we use the smoothed seismicity rate model to distribute the remaining part of the seismicity rate in each seismic source zone.Finally,we calculate the seismic hazard maps from the seismicity rate model of the Sichuan-Yunnan region using the OpenQuake engine and the ground motion prediction equations model.This result could be a scientific basis for regional seismic hazard analysis.

关 键 词：特大地震 川滇地区 地震危险性预测模型 锥形古登堡-里克特关系 背景地震源 

分 类 号：P315[天文地球—地震学]