地震影响场应急评估方法研究

Study on the emergency evaluation of earthquake influence field

为了提高地震影响场应急评估的准确性,首先分析了西南地区不同震级地震与当地活断层之间的相应关系,然后给出了不同震级地震各烈度区的长短轴经验矩阵;基于此,结合地震应急指挥中心的工作实践,提出了一种地震影响场应急评估方法。地震影响场应急评估分为初评估和动态修正两个阶段。初评估阶段为震后0.5~1 h,实现影响场方向和各烈度区面积的准确评估;动态修正阶段为震后1~2 h,实现影响场空间分布的准确评估。初评估阶段以微观震中为中心、以对应震级的最近断层方向为影响场方向、采用矩阵给出的该震级各烈度区长短轴长度进行影响场计算;动态评估是在初步评估的基础上,利用余震信息快速判定宏观震中和影响场方向,并将影响场中心(宏观震中)和方向修正到基于余震信息判定的结果上。最后,以四川芦山7.0级地震为例,介绍了此方法的技术流程、实用范围和可靠性。

In order improve the accuracy of earthquake influence field emergency evaluation,the relations between the historical earthquakes with different magnitudes and the active faults in southwest China were first studied,and an empirical matrix to calculate the major and the minor axes of the seismic intensity zones caused by these earthquakes were built. Combined with of the work of Earthquake Emergency Command Center of the Earthquake Administration of Yunnan Province,a new method of emergency evaluation of the earthquake influence field was then proposed. The proposed evaluation method is divided into two procedures:( 1) Preliminary evaluation. It works in 0. 5- 1 hour after the earthquake,and produces the accurate direction and the intensity area of the earthquake influence field;( 2) Real-time correction. It works in 1- 2 hours after the earthquake,and produces the accurate spatial distribution of the earthquake influence field. At the stage of preliminary evaluation,the microscopic epicenter was taken as the center of the earthquake influence field,the strike of the nearest fault as the direction of the influence field,and the influence area was calculated by the major and minor axes. At the stage of real-time correction,the macro-epicenter and the direction of the influence field were rapidly determined according to the aftershock information,and then were corrected according to the aftershock information. Finally,Lushan,Sichuan,Ms7. 0 earthquake on April 20,2013 was take as an example to show how to use this method.