【摘要】 利用广东数字地震台网的资料计算了2004年9月17日广东阳江MS4.9地震的震源机制为:节面走向57°,倾角47°,滑动角69°,主压应力方向342°,倾角0°,主张应力方向252°,倾角75°,属逆断层性质;地震矩为1.69×1015N.m,应力降为1.7MPa,震源半径为876m。根据阳江地区震前22个ML>2.5的中小地震震源参数,得到一些经验关系。S波拐角频率随时间的变化显示出MS4.9地震前有下降趋势;阳江序列P轴方位角的变化显示出震前4个月应力开始趋于一致。更多还原

【Abstract】 According to the Guangdong Digital Seismic Network records, the focal mechanism is obtained from the earthquake （M_S4.9） in Yangjiang on September 17, 2004. The strike is 57, the dip angle is 47 and the rake is 69 of the nodal plane, the azimuth and the dip angle of principal compressional stress axes P is 342 and 0, respectively; the azimuth and the dip angle of principal extensional stress axes T is 252 and 75, respectively, the type is reverse faulting. The seismic moment is 1.6910¹⁵ Nm, the stress drop is （1.7） MPa, the source radius is 876m of this earthquakes. Some relations are obtained by analyzing source parameters of the 22 moderate-small earthquakes in Yangjiang area. The descent trend of corner frequency of S wave is showed by the changes of the time before the earthquake （M_S4.9）, the azimuth of axes P of Yangjiang sequence show that the stress has begun to be identical in four months before this event.更多还原