基于卫星重力和地震活动图像的构造特征分析  

ANALYSIS ON STRUCTURAL FEATURES: INSIGHTS FROM SATELLITE-DERIVED GRAVITY MODEL AND SEISMIC PATTERN

作　　者：陈安国[1] 周涛发[1] 王健[2] 刘东甲[1] 葛粲[1] 

机构地区：[1]合肥工业大学资源与环境工程学院,合肥230009 [2]中国地震局地球物理研究所,北京100081

出　　处：《地震地质》2016年第3期696-710,共15页Seismology and Geology

基　　金：国家自然科学基金重大国际(地区)合作与交流项目(41320104003);中国地质调查局地质调查工作项目(12120114039701;1212011220243;1212011220244)共同资助

摘　　要：利用中国地震监测台网积累的大量观测资料,通过将研究区网格化,计算得到每个节点的地震活动频度即密集值,将定性的震中分布图转化成定量图像。在选取起算震级时通过震级-频度G-R关系和震级-序号法计算研究区最小完整性震级M_C,给出起算震级和时间。使用基于CryoSat-2和Jason-1卫星观测数据的V23.1重力模型,自由空气重力异常经过布格板校正和SRTM30地形数据做地形校正,得到完全布格重力异常。文中对邢台地震区和郯庐断裂带安徽段进行了实例研究:邢台地震区布格重力异常呈NE向狭长条形U型特征,异常位置与束鹿断陷盆地吻合,中、小地震密集值等值线受到重力U型条带的限制,剖面图显示密集值的极值处于重力U型变化的谷底位置;郯庐断裂带安徽段布格重力异常及不同高度的向上延拓结果具有很好的线性和梯度,地震活动图像长轴方向以及震源机制解发震断层节面走向呈NNE,显示郯庐断裂带安徽段是1条现今仍具有控震能力的深大断裂;对发生在郯庐断裂带附近的安庆M4.8地震,使用边界识别TDX方法进行了1︰20万实测重磁数据的隐伏边界解译,结合研究区深地震反射剖面探测成果,探讨了安庆地震的发震断层。In this paper,based on a large number of cumulative observational data from the seismic monitoring network in China,we grid the research area to calculate the density values at each grid node and convert the qualitative earthquake epicenter distribution to quantitative seismic pattern.Minimum magnitude of completeness（ MC） is determined by magnitude-rank analysis,which provides lower limit earthquake and original time. New satellite-derived gravity model v23. 1,which is based on satellites Cryo Sat-2 and Jason-1 data,is used to determine the Bouguer gravity anomaly derived from free-air gravity anomaly and elevation database sets SRTM30,and ultimately,the complete Bouguer correction is obtained. In this paper,the Xingtai earthquake zone and Tanlu fault zone（ Anhui segment） are selected for case study. Bouguer gravity anomaly presents a NE-trending U-shaped narrow strip in the Xingtai earthquake zone,and its location is consistent with Shulu Fault Basin. Grid density value contours are restricted by the U-shaped strip,and the extreme value of seismic activity density lies in the bottom of the U-shaped strip as shown in the cross section. The results of Bouguer gravity anomaly and upward continuations to the different heights show good linearity and gradient in the Tanlu fault zone（ Anhui segment）; and both long-axis direction of seismic pattern and nodal plane strike of seismogenic fault from focal mechanism solutions trend NNE.In short,the Tanlu fault zone（ Anhui segment） is a large deep-seated fault that still has the ability to control seismic activity along it. Based on the measured gravity and magmatic data,using the edge detection TDX method to interpret the concealed boundary of the Anqing M4. 8 earthquake near the Tanlu fault,and combining with the results from deep seismic reflection profiles of the study area,we discussed the causative fault of the Anqing earthquake.

关 键 词：卫星重力异常 地震活动图像 邢台地震 郯庐断裂带 安庆地震 

分 类 号：P315.2[天文地球—地震学]