摘要
2019年7月4—6日位于美国南加州城市Ridgecrest附近地区,在不足两天的时间内接连发生了一系列地震,其中包括震级达M W6.4和M W7.1的强震.震后两天对震中区产生的地表破裂进行了实地地质调查和测量,发现两次地震分别产生了NW方向长度50 km和NE方向长度10 km的两条破裂带.根据野外调查,NW方向的地表破裂表现出右旋走滑特征,是M W7.1地震产生的破裂带,而NE方向的地表破裂表现为左旋走滑性质,是M W6.4地震产生的破裂带.地表破裂野外调查和地震序列统计分析表明,NW方向是本次地震序列的主要破裂带,释放了本次地震的大部分地震矩.通过发震的时序关系和地震序列密集条带分布推断,本次地震是NE和NW两个方向应力作用下,两条共轭断层先后破裂产生的一组复杂共轭地震,推测M W6.4地震是一次强烈前震,促进了震级更大的M W7.1主震发生.
July 4—6,2019,located near Ridgecrest,Southern California,USA,a series of earthquakes occurred in less than two days,including the strong earthquakes M W6.4 and M W7.1.Two days after the earthquakes,the field geological survey and measurement of the surface ruptures in the epicenter area were carried out.Two fracture zones in 50 km length in NW direction and 10 km length in NE direction have been discovered after a series of Ridgecrest earthquakes.According to the field investigation,the dextral strike slip of surface ruptures in NW direction is produced by the M W7.1 earthquake,while the sinistral strike slip of surface ruptures in NE direction is produced by the M W6.4 earthquake.Combining with statistical analysis of earthquake sequence,it′s found that NW is the main direction fracture zones of this earthquake sequence and most of the earthquake energy is released.Based on the analysis of time series of earthquakes and dense strip distribution of earthquake sequences,it can be inferred that the earthquake is a group of complex conjugate earthquakes caused by the rupture of two conjugate faults in NE and NW directions.It also can be speculated that the M W6.4 earthquake is the strong foreshock,which promotes the occurrence of M W7.1 earthquake.
作者
马振宁
钱荣毅
Rufus Catchings
Mark Goldman
祁生文
MA ZhenNing;QIAN RongYi;Rufus Catchings;Mark Goldman;QI ShengWen(School of Geophysics and Information Technology,China University of Geosciences(Beijing),Beijing 100083,China;U.S.Geological Survey Earthquake Science Center(USGS-ESC),Moffett Field,California 94035,USA;Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
2021年第4期1206-1214,共9页
Chinese Journal of Geophysics
基金
国家自然科学基金面上项目(4197040734)
国家电网公司科学技术项目(52199918000C)联合资助.
