基于场地响应和量规函数对唐山5.1级地震的震级校正

Magnitude Correction of Tangshan MS5.1 Earthquake Based on Site Response and Gauge Function

摘要:

利用2010年以来河北省测震台网记录到的654个M_L ≥ 2.5地震波形数据，使用Moya方法联合反演计算震源谱及各台站场地响应。河北省测震台网实时接收168个台站数据，最终反演得到151个测震台站场地响应结果。结果显示，频率1~20Hz内各台站均存在不同程度的场地放大效应，随着频率的变化，各类基岩台的场地响应变化较为复杂。位于第四系沉积类的台站场地响应在低频段1~8Hz内放大效应显著，在高频段8~20Hz内呈现快速衰减趋势。选取2017年以来河北省测震台网记录的M_L ≥ 2.0地震数据，对各台站单台震级与台网平均震级进行对比统计、分析，最终得出代表河北地区的地方性震级M_L新量规函数。针对2020年7月12日河北唐山5.1级地震，利用本文得到的台站场地响应结果对震级偏大且有放大作用的台站进行放大作用消除，再分别用现用地方性震级M_L量规函数和河北地区地方性震级M_L新量规函数对单台震级进行重新计算，结果显示震级偏差均有所减小。

Abstract:

The Moya(2000)method was used to jointly invert the source spectrum and the site response of 654 earthquake events with M_L ≥ 2.5 recorded by Hebei Seismic Network since 2010. These events are from 168 stations with the actual inversion results of 151 seismic stations. The results show that each station has a different degree of site amplification effect within the frequency of 1~20Hz,The site response of various bedrock platforms varies with frequency is more complicated. Most of the station bases are Quaternary sedimentary stations. The site response shows obvious amplification effects in the low frequency range 1~8Hz,and fast attenuation trend in the high frequency band 8~20HZ. Selecting M_L ≥ 2.0 seismic data recorded by Hebei Seismic Network since 2017,with statistical analysis of the single earthquake magnitude of each station and the average earthquake magnitude of the network,we has obtained a new local M_L gauge function representing Hebei. In response to the Tangshan M_S5.1 earthquake of July 12,2020,we use the site response results obtained in this paper to eliminate the amplification effect of the station. Then we use the current gauge function and the newly obtained gauge function to recalculate the magnitude of a single station. The results show that the magnitude deviation has decreased.