地震研究

基于2011年10月—2015年12月福建测震台网金钟库区周边台站的连续波形数据,利用地震背景噪声互相关技术提取台站对间的经验格林函数,分周期(1～2 s,2～4 s和4～8 s)测量每天经验格林函数与参考格林函数的走时偏移,进而计算了库区各台站对之间的相对地震波速变化。结果表明:2～4 s周期内地下介质相对波速变化表现出夏高冬低的年变规律,与库区水位变化及当地降雨量存在明显的正相关性,说明在此周期范围内,水位变化及降雨量对波速变化的影响最大。2013年8—10月,仙游地区接连发生了4次ML≥4.0地震,其中在2013年9月4日仙游震群最大ML5.0地震发生后,波速变化出现趋势性下降,幅度约为0.1%,随后波速逐渐恢复,在整个震群活动后期,对库区介质波速的影响不明显。

Based on continuous seismic data of the stations in Fujian Seismic Network in the surrounding area of the Jinzhong Reservoir during Oct.,2011 and Dec.,2015,we extracted the empirical Green's function between station pairs by using seismic ambient noise correlation methods,and measured the travel-time shifts between the empirical Green's function and the reference Green's function periodically(1～2 s,2～4 s and 4～8 s),and then calculated the relative seismic velocity changes between the stations in the reservoir area.The results show that the relative seismic velocity changes for underground medium in the 2～4 s period show the annual variation rule of increases in summer and decreases in winter,which obviously correlated with the change of water level and precipitation in the reservoir area.It shows that the change of water level and precipitation have the greatest influence on the change of seismic velocity in this period.From Aug.,2013 to Oct.,2013,four ML≥4.0 earthquakes occurred successively in Xianyou area,among which,after the ML5.0 earthquake on Sep.4,2013,the wave velocity decreased by about 0.1%,and then the wave velocity recovered gradually.At the later stage of the whole earthquake swarm activity,the influence on the seismic velocity of the reservoir medium was not obvious.

引言
1 数据及方法
2 结果分析
3 结论

图1 金钟水库水位变化与仙游震群M-T图<br/>Fig.1 The water level change of Jinzhong reservoir and M-T map of Xianyou earthquake swarm

图1 金钟水库水位变化与仙游震群M-T图
Fig.1 The water level change of Jinzhong reservoir and M-T map of Xianyou earthquake swarm

表1 各地震台观测系统主要技术参数<br/>Tab.1 Main technical parameters of the seismic observation system in each seismic station

表1 各地震台观测系统主要技术参数
Tab.1 Main technical parameters of the seismic observation system in each seismic station

图2 研究区及地震台站分布(a)及金钟水库位置及仙游震群震中分布(b)<br/>Fig.2 Distribution of the study area and seismic stations(a),and the location of the Jinzhong reservoir and distribution of epicenters of the Xianyou earthquake swarm(b)

图2 研究区及地震台站分布(a)及金钟水库位置及仙游震群震中分布(b)
Fig.2 Distribution of the study area and seismic stations(a),and the location of the Jinzhong reservoir and distribution of epicenters of the Xianyou earthquake swarm(b)

图3 各台站数据可用性图<br/>Fig.3 Data availability for each station

图3 各台站数据可用性图
Fig.3 Data availability for each station

图4 DHTZ-XYXY台站对叠加后格林函数的能量干涉图<br/>Fig.4 Energy interferogram of Green's Functions after superposition of DHTZ-XYXY stations

图4 DHTZ-XYXY台站对叠加后格林函数的能量干涉图
Fig.4 Energy interferogram of Green's Functions after superposition of DHTZ-XYXY stations

图5 金钟库区3个周期的地下介质平均相对波速变化与库区水位<br/>Fig.5 The average relative seismic velocity changes for underground medium in three periods and water level in Jinzhong reservoir area

图5 金钟库区3个周期的地下介质平均相对波速变化与库区水位
Fig.5 The average relative seismic velocity changes for underground medium in three periods and water level in Jinzhong reservoir area

图6 金钟库区2～4 s周期地下介质平均相对波速变化与莆田地区降雨量<br/>Fig.6 The average relative seismic velocity changes for underground medium in Jinzhong reservoir area in 2～4 s period and precipitation in Putian region

图6 金钟库区2～4 s周期地下介质平均相对波速变化与莆田地区降雨量
Fig.6 The average relative seismic velocity changes for underground medium in Jinzhong reservoir area in 2～4 s period and precipitation in Putian region

图7 仙游震群序列震源深度时变(a)和频度(b)<br/>Fig.7 Focal depth time-varying(a)and frequency (b)diagrams of the Xianyou earthquake swarm

图7 仙游震群序列震源深度时变(a)和频度(b)
Fig.7 Focal depth time-varying(a)and frequency (b)diagrams of the Xianyou earthquake swarm

图8 金钟库区4～8 s周期地下介质平均相对波速变化与仙游震群序列<br/>Fig.8 The average relative seismic velocity changes for underground medium in Jinzhong reservoir area in 4～8 s period and the Xianyou earthquake swarm

图8 金钟库区4～8 s周期地下介质平均相对波速变化与仙游震群序列
Fig.8 The average relative seismic velocity changes for underground medium in Jinzhong reservoir area in 4～8 s period and the Xianyou earthquake swarm

安艳茹,张晓东.2015.利用背景噪声研究紫坪铺水库水位加卸载对库区地下介质波速的影响[J].中国地震,31(4):616-628.
陈翰林,赵翠萍,修济刚,等.2009.龙滩水库地震精定位及活动特征研究[J].地球物理学报,52(8):2035-2043.
陈颙.2009.汶川地震是由水库蓄水引起的吗?[J]中国科学,39(3):257-259.
段刚,蔡杏辉,陈惠芳,等.2017.福建台网地震目录[EB/OL].(2017-06-22)[2019-10-18].http://www.fjdzj.gov.cn/ca/2017011419000006.htm.
胡淑芳,秦双龙,李强,等.2018.福建仙游震群的孔隙压扩散特征[J].地震学报,40(2):172-183.
李强,李军,袁丽文,等.2015.福建仙游震群序列ML≥4.0事件震源机制与序列活动特征[J].地震,35(4):147-156.
刘志坤,黄金莉.2010.利用背景噪声互相关研究汶川地震震源区地震波速度变化[J].地球物理学报报,5(4):853-863.
马文涛,徐长明,李海鸥,等.2010.长江三峡水库诱发地震加密观测及地震成因初步分析[J].地震地质,32(4):552-563.
张致伟,程万正,梁明剑,等.2012.四川自贡—隆昌地区注水诱发地震研究[J].地球物理学报,55(5):1635-1645.
周斌,薛世峰,邓志辉,等.2010.水库诱发地震时空演化与库水加卸载及渗透过程的关系——以紫坪铺水库为例[J]地球物理学报,53(11):2651-2670.
Brenguier F,Shapiro N M,Campillo M,et al.2008.Towards forecasting volcanic eruptions using seismic noise[J].Nature Geoscience,1(2):126-130.
Clarke D,Zaccarelli L,Shapiro N M,et al.2011.Assessment of resolution and accuracy of the moving window cross spectral technique for monitoring crustal temporal variations using ambient seismic noise[J].Geophysical Journal International,2(186):867-882.
Lecocq T,Caudron C,Brenguier F.2014.MSNoise,a python package for monitoring seismic velocity changes using ambient seismic noise[J].Geophysical Research Letters,85(3):715-726.
Liu Z K,Huang J L,Peng Z G,et al.2014.Seismic velocity changes in the epicentral region of the 2008 Wenchuan Earthquake measured from three-component ambient noise correlation techniques[J].Geophysical Research Letters,41(1):37-42.
Ratdomopurbo A,Poupinet G.1995.Monitoring a temporal change of seismic velocity in a volcano:Application to the 1992 eruption of Mt.Merapi(Indonesia)[J].Geophysical Research Letters,22(7):775-778.
Wang Q Y,Florent B,Michel C,et al.2017.Seasonal crustal seismic velocity changes throughout Japan[J].Journal of Geophysical Research:Solid Earth,122:7987-8002.

备注

引言

1 数据及方法

2 结果分析

3 结论

期刊信息