濮阳小震集中区地震重定位及发震构造分析

Relocation of Earthquakes in Small Earthquake Concentrating Area of Puyang and Analysis of the Seismogenic Structure

利用濮阳周边数字地震台网近十年的震相观测报告数据及3级以上地震事件的波形记录,基于人工地震宽角反射/折射剖面的速度模型,采用Hypo2000地震定位法对研究区内1级以上287次地震事件进行绝对定位。同时,以Hypo2000绝对定位结果为初始位置,对濮城镇附近约25 km范围内的153个一级以上地震进行双差相对定位,获得更为准确的相对位置关系。定位研究结果表明:重新定位后研究区的小震震丛在震中和震源深度剖面上均呈现出两个分支:主支地震群沿聊—兰断裂分布,由少数地震组成的分支则分布于黄河断裂东侧。结合深地震反射剖面解释结果,推断濮城镇小震震丛的发震构造主要以聊—兰断裂为主,西部少数地震分支的发震断层为黄河断裂带,同时小震活动亦与油田开采注水活动密切相关。

In this paper,the seismic phase observation report and waveform records of M≥3 earthquakes in Puyang and its adjacent area during 2008-2018 were collected.Based on the velocity model of wide-angle reflection/refraction profile of artificial earthquake,the absolute location of 287 M≥1 earthquakes in the study area was carried out by using the Hypo2000 seismic location method.Meanwhile,taking the absolute positioning result of Hypo2000 as the initial position,the double difference location of 153 M≥1 earthquakes within 25 km around Pucheng town was carried out.The results showed that after relocation,two branches are shown both in the profile of epicenter and focal depth of the small earthquake cluster in Pucheng town:the main branch of earthquake swarm is distributed along the Liaocheng-Lankao fault,and the branch composed of a few earthquakes is distributed in the east side of the Yellow River fault.Combined with the interpretation results of deep seismic reflection profile,it is inferred that the Liaocheng-Lankao fault is the main seismogenic structure of the small earthquake cluster in Pucheng town,and the seismogenic fault of the branch of few earthquakes in the west is the Yellow River fault zone.The small earthquake activity is also closely related to the water injection activities in oilfield production.