海原活动断裂带破裂行为特征研究

Detailed Study of Holocene Paleoearthquakes of the Haiyuan Active Fault

通过对海原断裂带18个探槽资料的研究,分析得出海原断裂带10ka以来共发生10次古地震事件,这些古地震事件具有分级破裂的特征,第一次和最后一次是沿全断裂的破裂事件,其他都是沿次级段落的破裂事件。在时间上,古地震事件的分布是不均匀的,具有丛集的特征;在空间上,具有西段或中东段(中段)来回迁移的特征。沿全断裂的破裂事件震级约8.5级左右,沿次级断裂的破裂事件震级约7.5级左右。

Through studying eighteen trenches along the Haiyuan fault, ten paleoearthquakes were determined since ten thousand years ago. They have different rupture scales. The first and last events ruptured along the entire fault; the other events ruptured along secondary segments. The paleoevents are characterized by clustering in time and migrated back and forth from the west segment to middle - east segment. The magnitude of earthquakes along the entire ruptured fault is about 8. 5 and of those along the secondary ruptured segments is about 7.5.