地震前海平面异常变化和机理研究

根据国内外沿海大地震前后海平面变化的实例，分析海平面变化的前兆意义。资料证实，大部分近海大地震前存在局部海域可以识别的海平面异常变化。１９世纪以来，世界各地的验潮站记录了大量与地震有关的海平面变化实例，为定量分析提供了可能。最有代表的标准震例是１９４１年１１月葡萄牙亚速尔群岛８．３级大地震，我国渤海１９６９年７月在８日７．４级地震前后烟台站的验潮记录也显示出显著异常。海域构造环境和地震发生机制不同

Anomaly change of sea level before earthquakes and its mechanism

In this paper, the precursory sense of sea level change is analyzed based on sea level change cases of civil and oversea coast earthquakes. It is confirmed that local sea level changes abnormally before most earthquakes nearby sea. Since 19th century, tide - gauge stations all over the world have recorded lots of cases about sea level changes before earthquake, it furnishes possibility for quantitative analysis. The best example is the M8. 3 earthquake occurring in Azov archipelago, Portugal, on November 25 , 1941. The record of Lagos tide - gauge station shows that its sea level falls 30 cm one year before earthquake. The earthquake burst during anomaly recovery. In our country, the record of Yantai tide - gauge shows the anomaly before the M7.4 Bobal earthquake, July 18, 1969. Sea level anomaly characteristics are different according to tectonic and focal mechanism. Plate collision boundary, discrete boundary, transform faults and adjacent sea are sorted in this paper. The M8.3 Azov earthquakes, Nov. 25, 1941 and the M8.3 Chile earthquake, May 22, 1960 are examples of plate collision boundary earthquakes. Adjacent sea includes hack - arc basin and adjacent valley basin, the Niigata earthquakes, Japan, 1964 and the Bohai earthquake, China, 1969 are its examples. In transform fault coast, rise - fall movement is not obvious before earthquake, the sea level anomaly can be found when epicenter distance is small. The San Francisco earthquake, USA, 1906 and the Long Beach earthquake, USA, 1933 are its examples. There is no report on plate discrete boundary yet.