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笔者研究了日本及其附近地区8次地震后地震活动的迁移,发现,大多数情况下地震活动的迁移速度为几公里/年至100公里/年。可是,有时也会在大震之后立即引起离大震震源区几百公里以外地区的地震活动。在这种情况下,虽然极少发生6级以上大震,但迁移的视速度为每天100公里以上。在所有的情况下,地震活动都是沿包括大震震源区在内的板内地震构造带迁移的。我们注意到与板内大地震预报有关的一种有意义的现象,即在那些带上,大地震迁移开始之前一段比较短暂的时期内,在整个地震带上有时出现4级左右的小震活动。当空区处于地震迁移锋的后面时,随后很可能被地震填满。就板内地震活动而言,“地震空区”的概念对这些空区似乎是最合适的。虽然目前尚未发现地震迁移的物理机制,但这种现象有时对预报未来大地震很有帮助,并有助于我们了解板内地震构造的特征。
The author studied the earthquakes after 8 earthquakes in Japan and its vicinity and found that in most cases, the earthquakes migrated at a speed of several kilometers / year to 100 kilometers / year. However, it is sometimes possible to cause earthquakes within a few hundred kilometers from the source area of the epicenter immediately after the earthquake. In this case, although the magnitude 6 earthquake is rare, the apparent velocity of migration is more than 100 km per day. In all cases, the seismic activity migrated along the intraplate seismic structure including the focal zone of the major earthquakes. We note a significant phenomenon related to the prediction of large intraseismic earthquakes that there are occasional small earthquakes of about 4 magnitude across the entire seismic zone in a short period of time prior to the onset of major earthquakes . When the void area is behind the earthquake migration front, it is likely to be filled by the earthquake later. For intraseismic activities, the concept of “seismic zones” seems to be the most appropriate for these zones. Although no physical mechanism has yet been found for earthquake migration, this phenomenon is sometimes helpful in predicting future earthquakes and helps us to understand the characteristics of on-board seismic structures.