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1997年9月23日和26日,在广东省三水相继发生ML37和44地震。由于这两次地震震源浅(1km左右),具有震级小、烈度高和地震面波发育的特征。因震中位于盐矿开采区,震源深度与盐矿开采注水-抽水深度接近,故震源机制解表明该震为一次沿F7断层下滑错动的正倾滑型地震,显然,这与盐矿注水-抽水采盐有着成生联系。由于注水-抽水采盐使开采地段产生一定规模的采空区,注水沿F7断层的渗透所产生的孔隙压降低了有效正应力,加之渗透的润滑作用,在上部岩体重力作用下,采空区地段承受不了上覆岩体的重量,致使岩体沿F7断层向下滑动而诱发了塌陷地震。
On September 23 and 26, 1997, ML37 and M44 earthquakes occurred successively in Sanshui, Guangdong Province. As these two earthquakes are shallow (about 1km), they have the characteristics of small magnitude, high intensity and the development of seismic surface waves. Due to the fact that the epicenter is located in the salt mining area and the source depth is close to the water injection-pumping depth of the salt mining, the focal mechanism solution shows that the earthquake is a positive-slip-slip type earthquake that slid along the F7 fault. Obviously, Pumping salt has a connection. The pore pressure generated by water infiltration along the F7 fault decreases the effective normal stress due to water injection-pumping and salt-mining, resulting in a certain amount of goaf in the mining area. In addition, due to the penetrating lubrication, under the gravity of the upper rock mass, The area can not bear the weight of the overlying rock mass, causing the rock mass to slide downward along the F7 fault to induce the collapse of the earthquake.