利用波形互相关方法识别乳山震群中的重复地震,挑选一组在时间上跨越2015年5月22日ML 5.0地震的重复地震序列(repeating earthquake sequences,RES),利用测算单台直达P波第一个周期信号频散衰减特性的方法,估算乳山震群震源区介质品质因子,结果显示,不同路径下Qm值随时间的变化形态基本一致,即此次ML 5.0地震前Qm值升高,临震及震后Qm值下降并恢复至震前水平。同时,通过对震源区近场及远场应力状态的相关性分析,认为此次ML 5.0地震发生在远场作用下区域构造应力状态调整过程中,与区域构造的介质状态、断层分布、速度结构密切相关。
In this paper,we identified repeating earthquakes of the Rushan earthquake swarm in Shandong Province by using the waveform cross-correlation method and searched out a group of repeating earthquake sequences (RES) that spanned the ML 5.0 earthquake on May 22,2015.The medium quality factor of the focal area of the Rushan earthquake swarm is estimated by the method of calculating the dispersion and attenuation characteristics of the first period signal of direct P-wave of a single station.The results show that the shape of Qm with time is basically the same under different paths,that is,the Qm value increases before the ML 5.0 earthquake,decreases before the immediate occurrence of the earthquake and after the earthquake,and recovers to the level before the earthquake.At the same time,according to the correlation analysis of the near-field and far-field stress in the focal area,it is considered that the ML 5.0 earthquake occurred in the adjustment process of the regional tectonic stress under the far-field,which is closely related to the medium state,fault distribution and velocity structure of the regional structure.
2022,43(3): 10-17 收稿日期:2020-2-9
DOI:10.3969/j.issn.1003-3246.2022.03.002
基金项目:山东省地震局一般科研基金(项目编号:YB2206)
作者简介:李霞(1975-),女,高级工程师,主要从事地震预测研究工作。E-mail:cyfm@163.com
参考文献:
陈立德.震源硬化模型的理论、实验及观测事实依据[J].地震,2000,20(1):1-9.
陈为涛,甘卫军,肖根如,等. 3·11日本大地震对中国东北部地区地壳形变态势的影响[J].地震地质,2012,34(3):425-439.
郝召兵,秦静欣,伍向阳.地震波品质因子Q研究进展综述[J].地球物理学进展,2009,24(2):375-381.
蒋长胜,吴忠良.由"重复地震"给出的中国地震台网的定位精度估计[J].中国地震,2005,21(2):147-154.
李铂,崔鑫,苗庆杰,等. CAP方法反演乳山震群3.0级以上地震震源机制解[J].华北地震科学,2016,34(3):14-19.
李旭芬,刘建朝,张学仁,等.牟平-乳山金矿带构造特征及成矿预测[J].黄金科学技术,2013,21(3):10-15.
李宇彤,吴忠良,蒋长胜,等.利用辽宁区域地震台网记录分析"重复地震"[J].地震学报,2008,30(4):383-396.
林建民,王宝善,葛洪魁,等.重复地震及其在人工探测中的潜在应用[J].中国地震,2006,22(1):1-9.
刘方斌,曲均浩,李亚军,等.山东乳山地震序列震源机制解一致性参数特征[J].地震地质,2018,40(5):1 086-1 099.
刘希强,孙庆文,李红,等. 1999年辽宁岫岩5.4级地震前后P波衰减频散特征[J].地震学报,2005,27(5):477-487.
刘希强,陈朝辉. 1999年集集强震震源区附近地震P波衰减频散特征研究[C]//中国地球物理学会.中国地球物理学会第22届年会论文集.成都:四川科学技术出版社,2006:359-360.
梅世蓉,冯德益,张国民,等.中国地震预报概论[M].北京:地震出版社,1993.
曲均浩,王长在,刘方斌,等.乳山序列地震分布与震源区速度结构的关系[J].地震地质,2019,41(1):99-118.
宋明春,张京信.胶南造山带西段区域构造格局及变形特征[J].山东地质,1997,13(1):85-91.
王来明,宋明春,王沛成.胶南-威海造山带研究进展及重要地质问题讨论[J].山东地质,2002,18(4):78-83.
王鹏,郑建常,谭毅培.利用重复地震研究山东乳山地区地壳介质波速变化[J].地震学报,2016,38(5):728-738.
辛魏.山东省乳山市东峒岭金矿床地质特征研究[J].世界有色金属,2017,(14):192-193.
杨喜安,赵国春,宋玉波,等.胶东牟平-乳山成矿带拆离断层控矿特征及找矿方向[J].大地构造与成矿学,2011,35(3):339-347.
尹京苑,刘岚,王华林,等.日本3·11大地震对郯庐断裂带(中南段)位移场影响的数值模拟研究[J].地震地质,2015,37(3):928-938.
赵振,李欣.海城地震震源区的地震尾波衰减特征[J].中国地震,1995,11(1):62-71.
郑建常,曲利,曲均浩,等.乳山震群大小台网地震定位的对比研究[J].地震地质,2015,37(4):953-965.
周龙泉,刘桂萍,马宏生,等.利用重复地震观测地壳介质变化[J].地震,2007,27(3):1-9.
Doornbos D J. Observable effects of the seismic absorption band in the earth[J]. Geophys J Int, 1983, 75(3):693-711.
Igarashi T, Matsuzawa T, Hasegawa A. Repeating earthquakes and interplate aseismic slip in the northeastern Japan subduction zone[J]. J Geophys Res:Solid Earth, 2003, 108(B5):2249.
Jin A S, Aki K. Spatial and temporal correlation between coda Q-1 and seismicity and its physical mechanism[J]. J Geophys Res:Solid Earth, 1989, 94(B10):14 041-14 059.
Li L, Chen Q F, Cheng X, et al. Spatial clustering and repeating of seismic events observed along the 1976 Tangshan fault, North China[J]. Geophys Res Lett, 2007, 34(23):L23309.
Schaff D P, Richards P G. On finding and using repeating seismic events in and near China[J]. J Geophys Res:Solid Earth, 2011, 116(B3):B03309, doi:10.1029/2010JB007895.
Shelly D R, Ellsworth W L, Hill D P. Fluid-faulting evolution in high definition:connecting fault structure and frequency-magnitude variations during the 2014 Long Valley Caldera, California, earthquake swarm[J]. Journal of Geophysical Research:Solid Earth, 2016, 121(3):1 776-1 795.