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该地震发生在北东向茅山活动断裂与北西向芳山-老虎山活动断裂的交汇部位。本文研究了主震与若干余震的震源机制解,并应用零矢量方法确定了地震破裂面的走向。研究结果表明,该地震是在北东东向挤压应力作用下,沿着茅山断裂带东支发生了右行走滑错动兼有正断层性质的倾滑分量。根据对余震的观测可知,溧阳地震的震源体积与b值均偏小。运用Wyss方法及Gibo Wicz经验公式粗略估算了溧阳地震的应力降、地震矩与视应力。同时,根据野外地质观察指出,该地区之所以在最近五年来重复发生两次破坏性地震,可能与北西向芳山-老虎山断裂带的左行错动引起北东向茅山断裂带闭锁有关。
The earthquake occurred at the junction of the active fault in the Maoshan Mountains in the NE direction and the active fault of the Fangshan-Laohushan Mountain in the NW direction. In this paper, the focal mechanism solutions of main and some aftershocks are studied, and the zero-vector method is used to determine the strike of the earthquake rupture plane. The results show that the earthquake is a component of the right-lateral slip-faulting and normal faulting along the eastern branch of the Maoshan fault zone under the compressional stress of NE direction. According to the observations of aftershocks, we can see that the focal volume and b value of the Liyang earthquake are both small. The Wyss method and the Gibo Wicz empirical formula are used to roughly estimate the stress drop, seismic moment and apparent stress of the Liyang earthquake. At the same time, according to the field geological observation, the reason why the region repeated two devastating earthquakes in the recent five years may be related to the blockage of the NE-trending Maoshan fault caused by the left-hand wobble of the Fangshan-Laohushan fault belt in the northwest.