利用祁连山主动源资料研究2016年门源6.4级地震前后波速变化

Using the Active Source Data of Qilian Mountain to Study the Wave Velocity Change before and after the Menyuan M_S6.4 Earthquake in 2016

采用叠加、互相关、插值拟合等方法对祁连山气枪主动源台网数据进行处理,针对2016年1月21日青海门源6.4级地震前后气枪激发地震P波、S波震相的走时变化特征进行了分析,结果表明,地震前约6个月时,震中附近3个台站的相对走时出现下降变化(走时减少),至震前约3个月时低值异常恢复正常,之后再次出现走时下降变化,地震即发生于走时变化恢复过程中。S波走时变化最大下降幅度达18ms,震后走时变化逐渐恢复正常,且3个台站变化趋势较为一致,其中,距震中最近的台站的S波走时变化最明显(ZDY38台),较远台站的走时变化幅度较小,其变化特征与震源区位置有关。走时缩短意味着速度增加,可能与区域应力积累间存在一定的关系。

By using the methods of stack,cross correlation and interpolation of Qilian Mountains active source network data processing,we analyzed the air-gun travel time variation characteristics of phase P-wave and S-wave of the January 21,2016 Menyuan M_S6.4 earthquake,Qinghai. The results show that about 6 months before the earthquake,the relative time of three stations near the epicenter showed a decline（travel time decrease） and low the value anomaly returned to normal about 3 months before the earthquake. After that there appeared a travel time decrease,and the earthquake occurred in the recovery process. The maximum decrease of S-wave travel time was18 ms,and the change of travel time after the earthquake was normal. The variation trend of the 3 stations is consistent,among which the S-wave travel time is the most obvious at Station ZDY38 which is closest to the epicenter. The variation of travel time is smaller at the farther stations and is related to the regional stress accumulation. The shortening of travel time means the increase of the velocity.