2016年8月24日意大利Mw6.2地震近场地震动方向性效应

摘要

为研究2016年8月24日意大利中部Mw6.2地震的断层破裂方向性效应,依据断层走向将强震动观测台站划分为SE和NW两组,比较两组记录的地面峰值加速度PGA、地面峰值速度PGV、拟加速度反应谱PSA和重要持时DSR.结果显示:NW组观测到的PGA,PGV和PSA普遍大于SE组,PGA和PGV的观测值与预测值的残差随方位角变化明显;NW组观测到的DSR值整体小于SE组,由此推断此次地震存在明显的方向性效应.在此基础上,采用反演方法,确定了该地震的震源为双向非对称破裂,主破裂方向大约介于345°-360°之间,主破裂长度约占整个破裂的70％-80％,破裂速度为2.2-2.5 km/s,反演结果印证了两组台站数据的地震动参数差异是由断层破裂方向效应所引起的.%For investigating the rupture directivity effect of the central Italy Mw6.2 earthquake on August 24,2016,more than 150 strong motion stations are separated into two groups,which are SE and NW,according to the fault strike.Comparing the PGA,PGV,pseudo-acceleration response spectrum (PSA) and significant duration DsR of two groups,the results show that:the observed PGAs,PGVs and PSAs of NW group are larger than those of SE group;the residuals between the observed and predicted PGAs and PGVs are significantly correlated with the azimuth;the observed DsR of NW group is smaller than that of SE group.From these observations we deduce that the rup-ture directivity effect exists in this earthquake.Furthermore,the inversion for source rupture parameters using PGAs and PGVs,respectively,shows that the rupture is bilateral,and the Mw6.2 earthquake predominantly ruptured in the direction 345°-360°,accounting for 70％-80％ of the total rupture,and the rup-ture velocity is 2.2-2.5 km/s.These results validate the conclusion that the differences of ground motion parameters between two groups of stations mightbe caused by the rupture directivity effect.