青藏块体东北缘断层形变综合指标异常与岷县漳县6.6级等强震关系

Abnormities of Synthetic Norms for Fault Deformation in the Northeastern Margin of Qinghai-Tibet Block and their Relationship with Strong Earthquakes Containing Minxian-Zhangxian M_S6. 6 Earthquake

采用截至2013年底青藏块体东北缘的跨断层短水准流动观测资料,基于灰色关联度计算,提炼了祁连山—海原—六盘山、西秦岭主要构造断裂及分段的正逆断垂向活动综合指标,对强震尤其是2013年甘肃岷县漳县6.6级震前中短期异常,及与周边大震孕育—发生或影响的可能关系进行了研究。结果表明:(1)6级左右地震前相关构造及其附近中短期异常明显;综合指标对与周边8级特大地震孕育—发生可能存在一定关联、大尺度区域构造应力场的变化也有一定程度反映。(2)2013年甘肃岷县漳县6.6级震前西秦岭构造北—西部至六盘山断裂综合指标异常显著且集中,发震的西秦岭构造短期变化幅度较大。

Based on computation of grey relation degree, using mobile observation data of cross-fault short-leveling up to the end of 2013, we refine the synthetic norms for normal-thrust vertical activity of main fractures and their segments in Qilian Mountain-Halyuan-Liupan Mountain and Western Qinling Mountains, and studied the middle- short-term abnormities before the strong earthquakes especially the Minxian-Zhangxian Ms6. 6 earthquake in 2013, and their possible relationship with preparation, occurrence and influence of strong earthquake in the surrounding area. The results show that： （1） There existed obvious medium-short-term abnormities before the earthquake of magnitude about Ms6.0 in the related tectonic region and its nearby. The synthetic norms are related to the preparation and occurrence of Ms8. 0 earthquakes, and could reflect the variation of large-scope regional tectonic strain field. （2） Before the Minxian-Zhangxian Ms6. 6 earthquake, the abnormities of synthetic norm were remarkable and concentrated from the north and west of Western Qinling Mountains Faults to Liupan Mountain Fault, and the short-term variation range was relatively obvious at the seismogenic structure of Western Qinling Mountains Fault.