温州珊溪水库地震重新定位与速度结构联合反演
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摘要
通过震源位置和速度结构联合反演方法,利用浙江和福建区域地震台网和珊溪水库台网给出的P波走时资料,得到了珊溪水库地区的三维速度结构,重新确定了珊溪水库地震的震源参数。结果表明:①震中总体呈现NW向分布,NW走向的双溪-焦溪垟断裂可能为珊溪水库地震序列的发震断层。②珊溪水库地震震源深度最大为9.5km,平均为5.4km,小于华南地震区10km的平均震源深度。③水库北、南两岸的地震较浅,震源深度均小于5km,水库淹没区地震较深。水库诱发地震之初的几年中震源深度有一个逐渐变大的过程,这可能是由于库水逐渐往深部下渗,从而进一步诱发了更深处的地震所致。④研究区存在一个低P波速度异常区,低速区位于水库淹没区内的多组断裂交汇部位,地震大多发生在低速异常区内。这可能与水库蓄水后库水下渗有关。
Using the data of P wave travel time recorded at the Shanxi-reservoir seismological network and Zhejiang and Fujian provincial networks,we implemented a simultaneous inversion of earthquake relocation and velocity structure,got the new location of earthquake in the Shanxireservoir.The results show that:(1) The overall of epicenter to the distribution is to NW,the Shanxi-reservoir seismicity has a close relationship to the Shuangxi-Jiaoxiyang fault.(2) The focal depth of Shanxi-reservoir seismicity is 5.4km in an average,less than the average focal depth of earthquake zone in South China.(3) In the reservoir shore,the focal depth is shallower,and it is deeper in the reservoir inundation area.In the beginning of reservoir induced seismicity,focal depth increases gradually,and this may be due to the deep infiltration of water gradually induced a greater depth of the earthquake cause.(4) There is a low P wave velocity anomaly in the study area.Low-velocity zone in the reservoir inundation area is the intersection of multiple fracture sites.Shanxi-reservoir seismicity mostly occurred in the low-speed region.This may be related to water infiltration.
Using the data of P wave travel time recorded at the Shanxi-reservoir seismological network and Zhejiang and Fujian provincial networks,we implemented a simultaneous inversion of earthquake relocation and velocity structure,got the new location of earthquake in the Shanxireservoir.The results show that:(1) The overall of epicenter to the distribution is to NW,the Shanxi-reservoir seismicity has a close relationship to the Shuangxi-Jiaoxiyang fault.(2) The focal depth of Shanxi-reservoir seismicity is 5.4km in an average,less than the average focal depth of earthquake zone in South China.(3) In the reservoir shore,the focal depth is shallower,and it is deeper in the reservoir inundation area.In the beginning of reservoir induced seismicity,focal depth increases gradually,and this may be due to the deep infiltration of water gradually induced a greater depth of the earthquake cause.(4) There is a low P wave velocity anomaly in the study area.Low-velocity zone in the reservoir inundation area is the intersection of multiple fracture sites.Shanxi-reservoir seismicity mostly occurred in the low-speed region.This may be related to water infiltration.
引文
[1]浙江省地震局、华东勘测设计研究院,1994,浙江省飞云江珊溪水库工程水库诱发地震预测研究工作报告。
郭贵安、冯锐,1992,新丰江水库三维速度结构和震源参数的联合反演,地球物理学报,35(3),331～341。
廖其林、王振明、邱陶兴等,1990,福州盆地及其周围地区地壳深部结构与构造的初步研究,地球物理学报,33(2),163～173。
刘福田、李强、吴华等,1989,用于速度图像重建的层析成像法,地球物理学报,32(1),46～61。
王椿镛、林中洋、陈学波,1995,青海门源-福建宁德地学剖面的综合地球物理研究,地球物理学报,39(3),590～598。
王椿镛、陈运泰、邵占英,1998,中国东南陆缘的深部结构与动力学过程,地壳形变与地震,18(2),1～8。
吴健生、劳秋元,1995,扬子-南华构造区东部地壳波速结构的分析,地震地质,17(1),47～51。
张国民、汪素云、李丽等,2002,中国大陆地震震源深度及其构造含义,科学通报,47(9),663～668。
郑欣森、朱介寿、宣瑞卿等,2003,华南地区地壳速度结构分析,沉积与特提斯地质,23(4),9～13。
周龙泉、刘福田、陈晓非,2006,三维介质中速度结构和界面的联合成像,地球物理学报,49(4),1062～1067。
Aki k,Lee W H k,1976,Determination of three-dimensional velocity anomalies under a seismic array using P arrival times fromlocal earthquakes(1):A homogeneous initial model,J Geophys Res,81,4381～4399.
郭贵安、冯锐,1992,新丰江水库三维速度结构和震源参数的联合反演,地球物理学报,35(3),331～341。
廖其林、王振明、邱陶兴等,1990,福州盆地及其周围地区地壳深部结构与构造的初步研究,地球物理学报,33(2),163～173。
刘福田、李强、吴华等,1989,用于速度图像重建的层析成像法,地球物理学报,32(1),46～61。
王椿镛、林中洋、陈学波,1995,青海门源-福建宁德地学剖面的综合地球物理研究,地球物理学报,39(3),590～598。
王椿镛、陈运泰、邵占英,1998,中国东南陆缘的深部结构与动力学过程,地壳形变与地震,18(2),1～8。
吴健生、劳秋元,1995,扬子-南华构造区东部地壳波速结构的分析,地震地质,17(1),47～51。
张国民、汪素云、李丽等,2002,中国大陆地震震源深度及其构造含义,科学通报,47(9),663～668。
郑欣森、朱介寿、宣瑞卿等,2003,华南地区地壳速度结构分析,沉积与特提斯地质,23(4),9～13。
周龙泉、刘福田、陈晓非,2006,三维介质中速度结构和界面的联合成像,地球物理学报,49(4),1062～1067。
Aki k,Lee W H k,1976,Determination of three-dimensional velocity anomalies under a seismic array using P arrival times fromlocal earthquakes(1):A homogeneous initial model,J Geophys Res,81,4381～4399.
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