In those regions earthquake swarms have occurred repeatedly in the past . 这些地区以前曾反复出现过地震群。
2.
The beginning and development of monitoring and predicting earthquake from 1970 to 1976 in sichuan province and the typical example for the protecting against earthquakes are described in this paper 摘要记述了1970 ~ 1976年四川地震群测群防的兴起和发展，介绍了四川群测群防、专群结合预测预报地震的典型事例，特别对松潘平武7 . 2级地震预测预报群测群防的作用作了反映。
