利用模板匹配滤波技术对2017年11月至2018年4月寻乌ML 3.8震群的遗漏地震事件进行检测,再利用波形互相关震相检测技术标定P、S波到时,采用双差定位方法进行重定位,结合震群分布、震源机制解、地质构造分析震群的发震构造。结果显示,对于寻乌ML 3.8震群共检测到遗漏地震36个,约为中国地震台网中心地震目录的47%,ML<1.2地震的完整性有较明显改善。重定位后震群分布更加集中,沿NE向优势展布。垂直于震群优势展布方向的深度剖面显示,震源深度总体上由NW至SE逐渐变浅,推测可能的发震断层倾向NW。综合地质构造、精定位、震源机制解推测,此次震群的发震构造为吉潭—留车断裂。
Matched filtering technology was used to detect missing seismic events in the Xunwu ML 3.8 earthquake swarm from November 2017 to April 2018. Then we determined P and S wave arrival times using seismic phase detection technology based on waveform cross correlation method,and used double-difference relocation method for relocation, The seismogenic structure of the swarm was analyzed by combining the distribution of the swarm, source mechanism solutions, and geological structures. The results show that a total of 36 missing earthquakes were detected in the Xunwu earthquake swarm, which is about 47% of the catalogue of network, the catalog completeness is obviously improved for earthquakes below ML 1.2. After relocation, the distribution of earthquake swarm becomes more concentrated, spreads along the NE direction. The depth profile perpendicular to the dominant distribution of the earthquake swarm shows that the depth of the earthquake source gradually shallows from NW to SE, suggesting a possible seismic fault inclination towards NW. Based on the geological structures,relocated earthquakes and focal mechanisms, it is speculated that the seismogenic structure of this earthquake swarm is the Jitan-Liuche fault.
2024,45(4): 10-17 收稿日期:2024-3-29
DOI:10.3969/j.issn.1003-3246.2024.04.002
基金项目:江西省地震局科技创新团队项目;中国地震局监测、预报、科研三结合课题(项目编号:3JH-202401049)
作者简介:汤兰荣(1983—),女,硕士,高级工程师,主要从事地震监测预报工作。E-mail:156878629@qq.com
*通讯作者:叶媛媛(1981—),女,专科,高级工程师,主要从事地震监测预报工作。E-mail:49371733@qq.com
参考文献:
范玉兰,林纪曾,胡瑞贺,等. 华南地区近震走时表的研制[J]. 华南地震,1990,10(2):1-16.
黄智权. 江西省志江西省地震志[M]. 北京:方志出版社,2003.
刘泽民,倪红玉,张炳,等. 基于FOCMEC方法反演震源机制解的交互式程序研制与使用[J]. 华北地震科学,2015,33(1):19-24.
倪红玉,刘泽民,洪德全,等. 2016年安徽无为MS 3.0震群序列发震构造与震后趋势研究[J]. 中国地震,2017,33(3):365-373.
倪红玉,谭毅培,邓莉,等. 2014年金寨ML(3.9)震群序列遗漏地震检测及发震构造分析[J]. 中国地震,2021,37(2):379-389.
单连君,张新东,王晓山. 2016年1月9日河北怀来ML 3.4震群发震构造分析[J]. 震灾防御技术,2017,12(3):557-564.
谭毅培,曹井泉,刘文兵,等. 2013年3月涿鹿微震群遗漏地震事件检测和发震构造分析[J]. 地球物理学报,2014a,57(6):1 847-1 856.
谭毅培,曹井泉,卞真付,等. 2013年8月河北蔚县小震群遗漏地震检测与发震构造分析[J]. 地震学报,2014b,36(6):
1 022-1 031.
谭毅培,邓莉,曹井泉,等. 2015年河北滦县震群发震机理分析[J]. 地球物理学报,2016,59(11):4 113-4 125.
汪素云,许忠淮. 中国东部大陆的地震构造应力场[J]. 地震学报,1985,7(1):17-32.
王亚玲,蔡玲玲,李冬圣,等. 2020年7月12日河北唐山MS 5.1地震发震构造及唐山断裂带三维模型[J]. 华北地震科学,2021,39(3):83-91.
谢富仁,崔效锋,赵建涛,等. 中国大陆及邻区现代构造应力场分区[J]. 地球物理学报,2004,47(4):654-662.
张淼. 地震定位和检测[D]. 合肥:中国科学技术大学,2015.
Earle P S, Shearer P M. Characterization of global seismograms using an automatic-picking algorithm[J]. Bull Seismol Soc Am, 1994, 84 (2): 366-376.
Gibbons S J, Ringdal F. The detection of low magnitude seismic events using array-based waveform correlation[J]. Geophys J Int, 2006, 165 (1): 149-166.
Peng Z G, Zhao P. Migration of early aftershocks following the 2004 Parkfield earthquake[J]. Nat Geosci, 2009, 2 (12): 877-881.
Schaff D P,Waldhauser F. Waveform cross-correlation-based differential travel-time measurements at the northern California Seismic Network[J]. Bull Seismol Soc Am, 2005, 95 (6): 2 446-2 461.
Snoke J A, Munsey J W, Teague A G, et al. A program for focal mechanism determination by combined use of polarity and SV-P amplitude ratio data[J]. Earthquake Notes, 1984, 55 (3): 15.
Snoke J A. Earthquake mechanisms[M]//James D E. Encyclopedia of Geophysics. New York: Van Nostrand Reinhold Company, 1989: 239-245.
Stevenson P R. Microearthquakes at Flathead Lake, Montana: a study using automatic earthquake processing[J]. Bull Seismol Soc Am, 1976, 66 (1): 61-80.
Van Trees H L. Detection, estimation, and modulation theory[M]. New York: John Wiley & Sons, 2001, 208-210.
Wang J, Xiao Z W, Liu C, et al. Deep learning for picking seismic arrival times[J]. Journal of Geophysical Research: Solid Earth, 2019, 124 (7): 6 612-6 624.
Yamashita T. Simulation of seismicity due to fluid migration in a fault zone[J].Geophys J Int, 1998, 132 (3): 674-686.
Yang H F, Zhu L P, Chu R S. Fault-plane determination of the 18 April 2008 Mount Carmel, Illinois, earthquake by detecting and relocating aftershocks[J]. Bull Seismol Soc Am, 2009, 99 (6): 3 413-3 420.