论文部分内容阅读
引言 美国地质调查局的地震预报研究基于这样的前提,①研究加利福尼亚5级地震密集区周围与应变或地震活动性变化有关的地震前兆现象;②对整个圣安德烈斯断层系进行长期大地测量,同时研究其微震活动性。与此同时,开始目的在于表征与地震破裂有关的物理过程的实验研究。 为了使地震前兆的探索系统化,必须研究震源区不比震源深度明显小的频繁发生的M≥5级地震的地区。这些地区的地震频度必须是在一个震源尺度范围内架设两三台地震仪,每两、三年就能记录到一次这样的地震。圣·胡安色蒂斯塔以南圣安德烈斯断层上有50公里的一段是加利福尼亚州过去40多年中5级地震最密集的地带。因为其中强地震的发震率相对稳定,
Introduction The United States Geological Survey’s earthquake prediction study is based on the premise of (1) studying the seismic precursory phenomena associated with changes in the magnitude of seismic or seismicity around Class 5 seismic areas in California; (2) conducting long-term geodetic surveys of the entire San Andrés Fault System , While studying its microseismic activity. At the same time, the initial purpose is to characterize the experimental study of the physical processes associated with the earthquake rupture. In order to systematize the exploration of earthquake precursors, it is necessary to study the frequent occurrences of M≥5 earthquakes in which the source area is not significantly smaller than the focal depth. The frequency of earthquakes in these areas must be such that two or three seismographs are erected within one source scale and such earthquakes can be recorded every two or three years. A section of 50 km above the San Andres Fault to San Juan, south of Santa Ana, is the most densely populated zone of magnitude 5 in California over the past 40 years. Because of the relatively stable seismogenic rate of the strong earthquakes,