2014年霍山M_(S)4.3地震前后重磁场变化特征及机理分析  

THE CHARACTERISTICS AND MECHANISM OF GRAVITY AND MAGNETIC FIELD CHANGES BEFORE AND AFTER THE 2014 HUOSHAN M_(S)4.3 EARTHQUAKE

作　　者：梁霄[1,2,3] 储飞 徐如刚[1,2,3] 孙鸿博 肖伟鹏[1,2] 王俊 LIANG Xiao;CHU Fei;XU Ru-gang;SUN Hong-bo;XIAO Wei-peng;WANG Jun(Anhui Earthquake Agency,Hefei 230031,China;Mengcheng National Geophysical Observation and Research Station,Mengcheng 233500,China;Anhui Provincial Joint Construction Key Laboratory of Subsurface Exploration and Earthquake Hazard Risk Prevention(in prep.),Hefei 230031,China)

机构地区：[1]安徽省地震局,合肥230031 [2]安徽蒙城地球物理国家野外科学观测研究站,蒙城233500 [3]安徽省地下结构探测与震灾风险防范联合共建重点实验室(筹),合肥230031

出　　处：《地震地质》2024年第5期1151-1171,共21页Seismology and Geology

基　　金：中国地震局地震监测、预报、科研三结合课题(3JH-202402026);中国地震局地震监测、预报、科研三结合课题(3JH-202401029);武汉引力与固体潮国家野外科学观测研究站开放基金(WHYWZ202209);中国地震局震情跟踪专项任务(2024010414);中国地震局地震科技星火计划项目(XH22002YA)。

摘　　要：文中利用安徽省及周边地区2010—2015年流动重力和2013—2014年流动地磁资料,系统分析了霍山地震前后重力和岩石圈磁场三分量随时间的变化特征,利用小波分析法提取震前重磁场变化不同分解尺度的小波细节,结合地下流体资料探讨了霍山地震的发震背景和震前地球物理场前兆异常明显的原因。霍山地震前,重力场与岩石圈磁场总强都形成了异常变化的高梯度带,异常范围约为100km,梯度带的走向与发震断裂一致,地壳形变与地下流体运移明显受到构造断裂的控制。岩石圈磁场总强在霍山地区出现了较大幅度下降,重力场经历了“区域整体微小负值变化—形成重力异常高梯度带—在重力变化零等值线附近发震”的演化过程。震前半年“霍山窗”开窗,小地震活动显著增强,区域地壳运动水平显著上升,加速了区域应力状态的调整与地下流体的运移,导致了重磁场震前的显著变化;小波分析结果显示,磁场变化的极值点靠近重力场变化的零值线及断裂发育区域,表明重力场与岩石圈磁场的变化具有一定的相关性,进一步揭示了基于重力与岩石圈磁场变化等地球物理前兆信息预报地震的可能,结合区域应力场、地下流体、重力场与岩石圈磁场变化的综合分析,更有利于震前地震危险区的划定及危险性研判。Before the Huoshan earthquake,significant anomalies were detected in both the gravity and lithospheric magnetic fields.To comprehensively analyze the variations in these fields and their underlying mechanisms before and after the Huoshan earthquake,we used mobile gravity data from 2010 to 2015 and mobile geomagnetic data from 2013 to 2014 in Anhui Province and surrounding regions.Our analysis focused on gravity field changes from two perspectives:(1)the spatial and temporal variations in the gravity field and(2)the time series of gravity point values across the seismogenic fault(Tudiling-Luoerling fault).Additionally,we corrected for diurnal variations and long-term trends in the geomagnetic field,allowing us to track changes in the three components of the lithospheric magnetic field—total intensity,magnetic inclination,and declination—before and after the earthquake.Using wavelet multi-scale decomposition,we calculated and analyzed wavelet details at different decomposition scales for the gravity and magnetic field variations in the first half year before the Huoshan earthquake.Finally,in conjunction with underground fluid data,we examined the seismogenic background and explored the underlying reasons for the precursory anomalies observed in the geophysical fields.The research yielded the following conclusions:Prior to the Huoshan earthquake,an anomalous high-gradient zone in both the gravity field and the total strength of the lithospheric magnetic field was observed,extending approximately 100km.Notably,the total magnetic field strength in the Huoshan area significantly decreased before the earthquake.The gravity field exhibited a small initial decline,evolving into a high-gradient anomaly zone parallel to the seismogenic fault,which culminated in the earthquake occurring near the zero contour of gravity change.The alignment of the zero lines of gravity and magnetic field changes with the strike of the seismogenic fault suggests that tectonic faults play a critical role in controlling crustal deformation a

关 键 词：地震 重力场 岩石圈磁场 小波多尺度分解 地下流体 

分 类 号：P315.726[天文地球—地震学]