天津滨海爆炸事件检测与相对定位研究

2015年8月12日发生在天津滨海新区的化学品爆炸事故造成了严重的人员伤亡和财产损失。 基于区域地震台网记录的数字化连续地震波形资料, 对爆炸发生过程的精细分析是深入调查爆炸事故发生原因、 快速估计事故所造成灾害与损失的重要手段之一。 本文首先利用震相到时和质点运动轨迹信息对记录波形中能量较强的震相性质进行分析, 再通过模板匹配算法检测爆炸过程中是否存在两次大爆炸以外的小爆炸事件, 并对检测方法的效能进行检验, 最后依据波形互相关得到的震相到时差估计两次较大爆炸的相对位置。 计算结果显示区域台网记录波形中能量最大的体波震相可能为沿沉积层顶部传播的Pg震相, 垂直向能量最强的面波震相为Rg震相, 而能量较弱的初至震相可能为结晶基底首波; 爆炸过程中除了两次能量较大的爆炸以外还能检测到两次较小的爆炸事件, 其当量相当于约M_L0.5的地震; 基于两次大爆炸Pg震相相对到时信息得到第二次大爆炸发生在第一次大爆炸的北西侧, 两次爆炸位置距离约50~55 m。 本文研究结果为爆炸事故的调查分析提供了地震学依据。

Event Detection and Relative Relocation of the Massive Explosions in Binhai,Tianjin

A massive chemical explosion accident hit Tianjin Binhai on August 12, 2015, which caused serious casualties and property losses, and also caused a larger social repercussion. Tianjin seismic network center and China Earthquake Networks Center first reported in an official post on social media that there are two massive explosions, the first of which occurred at 11:34:04 (Beijing time) and only about 30s later another more powerful one occurred nearby, and the preliminary magnitude of these accidental explosions were estimated to be about M_L2.3 and M_L2.9 respectively. In this paper, we first indentified the properties of seismic phase with stronger energy based on the arrival time information and the trajectories of particles. And then detected whether there is other smaller explosion event except the two massive explosions using matched filter technique, and inspected the effects of detection method by 1000 times Bootstrap test. Further we estimated the relative position of two massive explosions using the differences of seismic phase arrival time information obtained from waveform cross-correlation phase detection. Seismic phase identification results show that the body wave seismic phase has the strongest energy recorded by regional seismic network may be the Pg phase which spread along the top of sediments. And the surface wave phase has the strongest energy recorded in vertical component may be the Rg phase. The first arrival seismic phase might be head wave phase spread along the crystalline basement. We detected two small suspected explosions, which occurred about 2 s before and 84 s after the first massive explosion, and their equivalent approximate to M_L0.5 earthquakes. The relocation result based on Pg phase arrival time differences shows that the second massive explosion is in the north west side of the first one, and the two explosions have about 50~55 m apart. According detailed seismology analysis of the explosion accident, we note that seismic network can play an important role in the process of accident emergency disposal. In the short time after the accident happened, when investigators cannot enter the explosion core region, analysis based on seismic waveform can help the government to understand the detailed process of explosion quickly and take timely and reasonable disposal method.