| 浙江珊溪水库2014年震群活动发震机理研究 |
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| 引用本文： | 王鹏,孙冬军,任烨,于俊谊,温燕林,朱艾斓. 浙江珊溪水库2014年震群活动发震机理研究[J]. 地震学报, 2017, 39(5): 648-658. DOI: 10.11939/jass.2017.05.002 |
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| 作者姓名： | 王鹏 孙冬军 任烨 于俊谊 温燕林 朱艾斓 |
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| 作者单位： | 1.中国上海 200062 上海市地震局 |
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| 基金项目： | 国家自然科学基金(41372222, 91214201)和上海市科学技术委员会科研计划(14231202600)联合资助国家自然科学基金91214201上海市科学技术委员会科研计划14231202600国家自然科学基金41372222 |
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| 摘 要： | 本文使用双差定位法对2014年9月12日至12月30日浙江珊溪水库发生的4184次地震进行重定位，并采用CAP方法对11次ML≥3.0地震事件的震源机制解进行反演，讨论了震群序列的活动特征及其与断裂之间的关系，分析了水库水位与地震之间的关系.重新定位的结果显示，在空间分布上，2014年震群序列发生在2006年震群序列NW向延伸的方向上，两者形成一条线性条带，该条带平行分布于双溪—焦溪垟断裂南侧.重定位得到的震源主要在0.7—6 km深度范围内分层分布，垂直于地震条带走向的震源剖面刻画出的结构面以高角度倾向SW.震源机制解结果显示多数地震为走滑型，均存在一个与地震条带走向一致的NW向节面，呈右旋走滑错动性质.考虑到断裂的定位误差，线性分布的震群活动极有可能沿双溪—焦溪垟断裂的破裂面活动，精定位的震源位置和震源机制刻画出了该断裂的几何结构和活动性质.但由于多数地震的震源深度在6 km以上，因此震群活动不能归为双溪—焦溪垟断裂活动的结果，即双溪—焦溪垟断裂不是这两次震群的发震构造，而且仍然属于水库诱发地震，而水库地震存在激发该断裂发生构造地震的可能.水库水位上升或者下降与震群活动关系不大，震群活动有随时间进一步增强的趋势, 可能是库水沿库底断层破裂面长期渗透和扩散增加了孔隙压所致.
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| 关 键 词： | 珊溪水库 震群序列 发震机理 水库诱发地震 双溪—焦溪垟断裂 |
| 收稿时间： | 2016-07-06 |
Investigation on the seismogenic mechanism of the 2014 earthquake swarm in Shanxi reservoir,Zhejiang Province |
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| Affiliation: | 1.Earthquake Administration of Shanghai Municipality, Shanghai 200062, China2.Earthquake Administration of Zhejiang Province, Hangzhou 310013, China |
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| Abstract: | We relocated 4184 earthquakes that occurred in Shanxi reservoir, Zhejiang Province from 12 September to 30 December, 2014 by using double-difference algorithm and determined the focal mechanism solutions of 11 ML≥3.0 earthquakes using the method of CAP in this paper. Based on the analysis of the high-resolution hypocenters and focal mechanisms, we investigated the activity features of the earthquake swarm and its relationship with the fault. On the mapping view, the epicenters of the 2014 earthquake swarm occurred in the extended northwest direction of 2006 seismic swarm belt, which forms a linear belt, running parallel to the south of the Shuangxi-Jiaoxiyang fault. The relocated hypocenters mainly distribute in layers from 0.7 to 6 km in depth. The cross section profile which is perpendicular to the seismic belt strike shows that the seismic plane dips to southwest with a high angle. Most focal mechanisms are strike-slip type. The nodal planes of the focal mechanism solutions that share the same orientation with the trend of the seismic belt distribution of NW show the feature of dextral strike-slip. Taking the fault location error into consideration, the earthquake swarm may align along the rupture plane of the Shuangxi-Jiaoxiyang fault. The high-resolution hypocenters and focal mechanisms delineate the structure and activity nature of the fault. Since there is no distinctive main shock in the earthquake swarm and most earthquakes locate above 6 km in depth, so we can conclude that the earthquake swarm was not caused by the activity of the Shuangxi-Jiaoxiyang fault, but induced by the reservoir water storage. However, it is possible that the Shuangxi-Jiaoxiyang fault may be activated by the water storage of reservoir to generate tectonic earthquake in the future. No evidence shows that there is obvious relationship between the level of the reservoir water storage and seismicity, and the swarm activity becomes greater with time, which may be caused by the pore pressure increasement due to the long term penetration of the reservoir water to the fault plane. |
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