以前的水库地震成因学说大多是认为地下断层积累了较高的应力,难以错动,当水库蓄水后,水通过裂隙渗透到断层面上,从而降低了断层面上的有效正压力或摩擦系数,导致断层的快速错动形成地震。然而这个学说对解释极浅源地震是有困难的。根据模拟实验,产生粘滑要有一定的正应力,否则仅能产生稳滑。在地下几公里的深度上围压比较小,因之在这样的深度是否存在粘滑条件还值得商榷。在这种情况下,用水去帮助断层错动更没有必要了。本文作者认为水库地区坚硬介质中大量小裂缝的接通是某些水库发生大量小震的原因。水进入裂缝后可加强裂纹的蠕滑,它使裂纹端部形成应力集中,有利于诸裂纹间的接通,而不是水进入断层后使断层本身发生错动而形成地震。当大量小裂缝互相接通时,即大量水库小震发生后,水又进一步渗透到小震活动区,使这一软弱区的范围(面积和深度)进一步扩大,形成应力调整区。如果在库区下方较深处有隐伏的蠕滑断层(走滑或倾滑),这可成为水库区另一个调整单元。它们之间相对完整的介质区即为应力积累区——震源区。在区域应力场的作用下,隐伏的蠕滑断层端部有剪应力集中,另外水库弱化区下方也有应力集中,这就使两个调整单元有接通的趋势,当积累单元的应力达到极限值时,这种接通就必然产生,并形成较大水库地震。另外,水库弱化区的下界面对蠕滑断层端部还有象力作用,它也有使该断层向弱化区传播的趋势,从而导致较大的水库地震。本模式说明,如果建水库前对未来诱发的地震进行预测时,应注意库区更深部是否有隐伏断层存在。 Most reservoirs before the earthquake theory suggests that the underground fault accumulates higher stress and is hard to slip. When water is stored in the reservoir, the water penetrates the fault surface through the fracture, so as to reduce the effective positive pressure or friction coefficient on the fault plane. Resulting in rapid dislocation of the fault to form an earthquake. However, this theory is difficult to interpret the extremely shallow earthquakes. According to the simulation experiment, there must be a certain amount of stick-slip normal stress, or only produce a smooth. The confining pressure is relatively small at the depth of several kilometers underground, so it is debatable whether there is stick-slip condition at such a depth. In this case, it is not necessary to use water to help break the fault. The authors believe that the connection of a large number of small cracks in the hard medium in the reservoir area is responsible for a large number of small earthquakes in some reservoirs. When water enters into the crack, it can strengthen the creep of the crack. It makes stress concentration at the end of the crack, which is beneficial to the connection between the cracks. Instead of the water entering the fault, the fault itself is dislocated to form an earthquake. When a large number of small cracks are connected to each other, that is, after a large number of reservoirs have occurred, the water further penetrates to the small earthquake activity area, further expanding the area (depth and area) of this weak area to form a stress adjustment area. If there is a hidden creeping fault (slippage or slippery) deeper in the lower part of the reservoir area, this could be another adjustment unit in the reservoir area. The relative integrity of the media between them is the stress accumulation zone - source zone. Under the action of the regional stress field, there is shear stress concentration at the end of the hidden creep fault, and there is stress concentration below the weakened zone of the reservoir, which makes the two adjusting units have a tendency to turn on. When the stress of the accumulating unit reaches the limit value When this connection is inevitable, and the formation of larger reservoirs and earthquakes. In addition, the lower interface of the weakened area of ​​the reservoir has an effect on the end of the creep fault, and it also tends to propagate the fault to the weakened area, resulting in larger reservoir earthquakes. This model shows that if future earthquakes are predicted before reservoirs are built, attention should be given to the presence of hidden faults in deeper parts of the reservoir.