【摘要】 2014年4月20日安徽省霍山发生MS4.3地震,是霍山地区41年以来发生的最大地震.本文首先基于安徽省及周边省份的地震台站资料,采用Hypo2000、CAP和PTD方法反演得到该地震的震源深度为8km;然后采用Hypo2000和HypoDD方法联合对主震和余震序列进行重新定位,结果显示该地震序列呈北东向分布,绝大部分余震分布在主震的西南侧;最后分别采用FOCMEC方法和CAP方法反演该地震的震源机制解,获得的反演结果非常接近,节面Ⅰ与节面Ⅱ的走向、倾角、滑动角分别为135°/70°/-30°与230°/60°/-160°.此外该地震的椭圆等烈度线呈北东向展布,结合该地区的历史地震和地震构造,认为该地震与北东向的落儿岭—土地岭断裂活动有关.已有震源机制解资料表明该地区构造应力场最大主压应力轴的方位角为267°,倾角为5°,最小主压应力轴的方位角为358°,倾角为4°,结合震源机制解和发震构造,认为该地震是在区域应力场作用下,落儿岭—土地岭断裂发生的一次右旋张性地震.更多还原

【Abstract】 A MS4.3earthquake occurred in Huoshan region,Anhui Province on20 April 2014,which is the largest earthquake in Huoshan region in recent 41 years.Several inversion methods such as Hypo2000,CAP and PTD methods,were used to get the focal depth of this earthquake,and the result shows the focal depth is about 8km.Based on the local broadband waveform data of available stations in Anhui Province and its adjacent province regional seismic networks,we relocated precisely the main shock and aftershock sequence with the Hypo2000 and HypoDD methods.The relocation results indicate that the earthquake sequence distributes along NE direction and most aftershocks are situated in the southwest of the main shock location.The focal mechanism soloutions of Huoshan MS4.3earthquake obtained with FOCMEC and CAP methods are basically consistent with each other,which is 135°/70°/-30°for nodal plane I and230°/60°/-160°for nodal plane Ⅱ.The major axis of field seismic intensity distribution map extends also along NE direction.Combined with history earthquakes and the regional geological structure data,it is deduced that this earthquake is likely related to the NE-wards Luo’erling--Tudiling fault.In addition,the azimuth and plunge of the maximum principal(compressive)stress axis of this region are 267°and 5°respectively,and 358°and 4°for the minimum principal(tensile)stress axis.Referring to the focal mechanism and the seismogenic structure,it is inferred that the Huoshan MS4.3earthquake is a dextral-slip normal event under regional stress field.更多还原