| 1994年美国北岭地震震源区构造应力状态反演及动力学解释 |
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| 引用本文： | 樊文杰,崔效锋,万永革.1994年美国北岭地震震源区构造应力状态反演及动力学解释[J].大地测量与地球动力学,2017,37(2):169-175. |
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| 作者姓名： | 樊文杰 崔效锋 万永革 |
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| 摘 要： | 针对余震震源机制解相对比较复杂、紊乱这一现象，借助ZMAP软件包的特点，提出在尽可能减少人为分区因素情况下，利用余震震源机制解反演计算震源区应力状态的具体思路。利用1994年美国北岭MW6.7地震的余震震源机制解，采用Michael提出的应力张量反演算法，对震后震源区的构造应力状态及其分布进行反演分析，探讨了地震后震源区应力状态的调整变化及其与地质构造的关系。结果表明：1）震后震源区最大主应力为近水平，方向为北北东向，北北东向的水平挤压是北岭震源区构造应力状态的一个明确特征；2）震后震源区深浅部的构造应力状态可能不完全一致，虽然深部和浅部的最大主应力方向均为北北东向，但震源区深部的应力类型为逆断型，震源区浅部的应力类型为走滑型，深部数据组的反演结果与区域构造应力场相一致。认为北岭地震后震源区深浅部构造应力状态的差异可能与震源区的地震构造和北岭主震的错动方式有关。北岭主震是一次逆冲型地震，地震发生后，在区域构造应力的作用下，震源区应力继续释放，隐伏的北岭断裂（可能包括其周围的小断层）继续逆冲运动，从而产生一些逆冲型的中小余震。深部构造应力状态没有发生明显的改变，但北岭断裂的逆冲运动有可能引起了震源区浅部应力状态的变化。
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| 关 键 词： | 北岭地震 震源机制解 构造应力场 反演计算 |
Tectonic Stress Inversion and Dynamic Implications in the 1994 Northridge Earthquake Source Region |
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| FAN Wenjie,CUI Xiaofeng,WAN Yongge.Tectonic Stress Inversion and Dynamic Implications in the 1994 Northridge Earthquake Source Region[J].Journal of Geodesy and Geodynamics,2017,37(2):169-175. |
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| Authors: | FAN Wenjie CUI Xiaofeng WAN Yongge |
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| Abstract: | For complicated types and distribution of the aftershock focal mechanism solutions，we give a concrete thought of inverting stress by aftershock focal mechanism with human factors as little as possible，according to the characteristics of ZMAP package.Based on aftershock focal mechanism solutions of the 1994 Northridge earthquake，using the stress tensor inversion method by Michael to analyze the tectonic stress state and its distribution in source region and preliminarily discuss the variations of stress state and its links to structure.The results show that the maximum principal stress in source region is nearly horizontal and trends NNE-SSW，which is an explicit characteristic of tectonic stress in Northridge earthquake source region.After Northridge earthquake，tectonic stress in deep and shallow area of source region are not entirely consistent.Even though the maximum principal axis is NNE both in deep and shallow area，the stress regime are thrust-faulting regime in deep area and strike-slip regime in shallow area.And the inversion result of deep data is consistent with region tectonic stress field.At same time，the difference of stress between deep and shallow area in source region is probably related to earthquake structure and movement mode of the Northridge earthquake with a stress regime of thrust-faulting.After the earthquake occurred, stress continued to release and blind fault kept on with thrusting movement under the action of regional tectonic stress. The thrusting movement of fault caused several thrusting earthquakes and stress state in deep area has no significant change. The thrusting movement of Northridge fault probably causes variations of stress and fault’s movement in the shallow area of source region. |
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| Keywords: | Northridge earthquake focal mechanism solution tectonic stress field inversion calculation |
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