地震前亚失稳应力状态的识别: 以5°拐折断层变形温度场演化的实验为例

利用岩石样品在失稳破裂前有“亚失稳”现象的实验结果，是不能预测大地震的。作此论断的主要理由是：①大地震与小地震的基本区别是，大地震在初始破裂发生后有一个长时间（几十秒，最长可达几百秒）的断层动态破裂过程，目前还不能预测断层的动态破裂何时会停止，因而不能预测地震的大小。②岩样的“亚失稳”实验结果即使可推广到野外地震发生的研究，充其量只能预测地震初始破裂的发生，但无法断定发生初始破裂后，地震是否会发展为一个断层面很大的大地震。③通过反演观测的地震波虽然可以得到地震动态破裂过程的认识，但由于断层破裂动力学目前还不能提供符合实际断层动态破裂过程的理论模型，没有理论模型就不能做预测。

Earthquake forecasts

It is impossible to predict the occurrence of large earthquakes by using experimental results of rock meta-instability stage before the rock instability and rupture. This judgment is supported by the following arguments: ① The significant difference between the large and small earthquakes is that, for the large ones, there is a long period （tens or hundreds of seconds） fault dynamic fracture after the initial fracture, while for small ones there isn’t. At present we can’t predict when the dynamic fracture will stop, and how large the final earthquake fault will be. ② If we prefer to predict tectonic earthquakes based on the rock meta-instability observation, then we can only predict the occurrence of initial fracture of an earthquake, rather than how large it will be. ③ By inverting the seismic wave observations we can understand the process of fault dynamic fracture. At present, the fault dynamics can’t give a practical theoretical model of fault dynamic fracture, therefore prediction cannot be made.