摘要
分析甘肃岷县M_S6.6地震前后潮汐变化发现,发震时刻引潮力处于最低相位点,显示引潮力的诱震属于典型逆冲断层作用类型。以潮汐周期为时间指示,利用NOAA卫星地面长波辐射(OLR)数据,分析震中及其邻近区域(30°~40°N,90°~110°E)地震前后(7月17~25日)地面长波辐射值的连续变化状况,结果显示,震前仅震中及其相关联断裂附近OLR发生了显著且连续的异常变化,在时间上经历了起始增温—异常加强—峰值—衰减—发震—平静的演化过程;在空间上异常区域覆盖震中,与汶川地震引发的应变积累正影响区之南北地震带北段基本吻合;在形态演化上,表现出沿断裂带分散—汇聚—分散的破裂过程,并与岩石应力加载破裂的初始微动破裂—扩张破裂—应力闭锁—地震爆发—恢复平静阶段的力学过程完全吻合。这可能预示该地震发震前后天体引潮力对处于临界状态的活动断层具有诱发作用以及长波辐射异常在一定程度上对地震构造应力应变过程辐射进行表征。
The tidal change before and after the Ms6.6（N34.5,E104.2）earthquake occurred on July 22,2013,in Minxian Gansu Province was analyzed.The tidal force was at the lowest phase point when the earthquake occurred,which indicated that the induced earthquake of the tidal force influenced by the thrust fault.According to the data of tidal cycle,the ground long-wave radiation variable condition before and after the earthquake at the epicenter and nearby area（30°～ 4°N,90°～ 110°E）was calculated based on the NOAA satellite data.The result showed that only the OLR of the epicenter and associated fractures appeared significant and continuous abnormal changing.In temporal,the change of the OLR：Initial warming→ strength→ peak→ attenuation→earthquake→return to the normal;in spatial,the abnormal region was consistent with the north area of the North-South Seismic Belt where it was affected by the positive strain accumulation of the Wenchuan earthquake area.In the morphological evolution,the OLR changing process：scattered→conversion→scattered along the fractures,which was fully consistent with the fracturing process of the rock stress loading：initial micro-cracking→expansion rupturing →stress lockout→earthquake →normal.The active faults in the critical state maybe induced by the tidal force in this earthquake,what＆#39;s more,the stress-strain process of earthquake could be characterized by the OLR anamoly.
出处
《中国地震》
北大核心
2017年第1期166-171,共6页
Earthquake Research in China
基金
地震科技星火计划项目(XH15050)资助
