目前,对地震前各种效应的持续时间还不完全清楚。我们认为,对于这个问题,应当从确立作为所有前兆效应依据和根源的物理基础着手进行研究。 根据巳确定的概念,地震是地球某一体积内应力逐渐增加的结果。当积累的应力达到埋藏条件下岩石的强度限时,便产生连续性的破坏从而发生地震。若由这一概念出发,则所有可能的地震前兆的物理基础,就是由应力所引起的岩石形变。这就产生了一个问题,在未来地震区内应以什么样的时刻作为应力作用的起点?在地球上未必能找到历史上只发生过一次强震的地方。地震常常是重复发生的。所 At present, the duration of various effects before the earthquake is not fully understood. In our opinion, we should start with the study of the physical basis for establishing all the bases and causes of precursor effects for this issue. According to the established concept, earthquakes are the result of a gradual increase in stress within a given volume of the Earth. When the accumulated stress reaches the limit of rock strength under burial conditions, it will result in continuous damage and earthquake. If we start from this concept, the physical basis for all possible earthquakes is the rock deformation caused by stress. This raises the question of what moment should be used as a starting point for stress in the future earthquake zone. There may not be a place on Earth where only a strong earthquake has occurred in history. Earthquakes are often repeated. The