地震研究

2011年云南盈江5.8级地震及震前短临跟踪预测^*

钱晓东,苏有锦,付虹,李琼

(云南省地震局,云南昆明 650224)

关键词：盈江地震; 震源机制; 地震学参数; 短临预测

Short-term and Impending Prediction of the Mar.10,2011,M_S5.8,Yingjiang,Yunnan Earthquake

QIAN Xiao-dong,SU You-jin,FU Hong,LI Qiong

(Earthquake Administration of Yunnan Province,Kunming 650224,Yunnan,China)

Keywords：Yingjiang M_S5.8 earthquake; focal mechanism; seismic parameters; short-term and impending prediction

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系统收集了2011年云南盈江5.8级地震前后的地震学基础资料,对盈江地震的地震地质背景、地震序列基本特征、地震烈度、发震断裂和区域应力场进行了详细分析。在此次盈江地震发生前,运用地震力标度、环境剪应力、地震序列h值、破裂时间法、能量释放方法,对该地震做了短临跟踪和预测。结果显示,盈江5.8级地震的发震断裂很可能是NE向的大盈江左旋走滑断裂,盈江地震前出现了诸多地学参数异常,这些异常对未来强震发生的时间和地点均有短临指示意义。

Collecting the firsthand seismic data before and after the M_S5.8 Yingjiang earthquake in Yunnan Province in 2010,we systematically analyze the seismo-geological background,the main characteristics of the sequence,the seismic intensity,the seismogenic fault of the Yingjiang earthquake as well as the regional stress field in the earthquake-stricken area. Particularly,by tracking the earthquake force scale,shear stress,h-value of earthquake sequence,time-to-failure and seismic energy,we conduct a short-term and impending earthquake and prediction 3 months before Yingjiang earthquake. The Dayingjiang fault,which is NE-trending,left-lateral and strike-slip,is most likely the seismogenic fault of this earthquake. There appeared a lot of anomalous seismic parameters before the earthquake,which significant to the short-term and impending prediction for the time and location of the future earthquakes in this area.

引言
1 盈江5.8级地震基本特征分析
2 盈江5.8级地震前短临跟踪和预测
3 讨论和结论

表1 盈江5.8级地震基本参数<br/>Tab.1 Basic parameters of the Yingjiang MS5.8 earthquake

表1 盈江5.8级地震基本参数
Tab.1 Basic parameters of the Yingjiang MS5.8 earthquake

图1 盈江地震震区台站分布(a)和历史地震地质构造图(b)<br/>Fig.1 Historical strong earthquakes and seismic stations(a)and geological structure(b)in Yingjiang MS5.8 earthquake region

图1 盈江地震震区台站分布(a)和历史地震地质构造图(b)
Fig.1 Historical strong earthquakes and seismic stations(a)and geological structure(b)in Yingjiang MS5.8 earthquake region

图2 盈江MS5.8级地震序列时空分布图(a)震区M-t图(2011-01-01～2011-04-10); (b)震中分布(黑色圆圈表示ML≥1.0地震,白色圆圈表示ML≥3.0地震)<br/>Fig.2 Temporal and spatial distribution of the Yingjiang MS5.8 earthquake sequence(a)M-t diagram(2011-01-01～2011-04-10);(b)Distribution of the epicenters

图2 盈江MS5.8级地震序列时空分布图(a)震区M-t图(2011-01-01～2011-04-10); (b)震中分布(黑色圆圈表示ML≥1.0地震,白色圆圈表示ML≥3.0地震)
Fig.2 Temporal and spatial distribution of the Yingjiang MS5.8 earthquake sequence(a)M-t diagram(2011-01-01～2011-04-10);(b)Distribution of the epicenters

表2 前震、主震序列震源深度h统计百分比<br/>Tab.2 Percentage of the focal depth h of the foreshocks and the main shock

表2 前震、主震序列震源深度h统计百分比
Tab.2 Percentage of the focal depth h of the foreshocks and the main shock

图3 盈江地震序列空间分布(a)前震和主震序列空间分布(ML≥2.0)(实心圆:前震序列; 空心方框:主震序列; 左下方框为震区局部放大图); (b)震源深度随时间分布(ML≥2.0)<br/>(实心大圆:4级以上地震)<br/>Fig.3 Spatial distribution of the Yingjiang MS5.8 earthquake sequence (a)Distribution of the fore-shocks and the main shock; (b)Epicenters(ML≥2.0)

图3 盈江地震序列空间分布(a)前震和主震序列空间分布(ML≥2.0)(实心圆:前震序列; 空心方框:主震序列; 左下方框为震区局部放大图); (b)震源深度随时间分布(ML≥2.0)
(实心大圆:4级以上地震)
Fig.3 Spatial distribution of the Yingjiang MS5.8 earthquake sequence (a)Distribution of the fore-shocks and the main shock; (b)Epicenters(ML≥2.0)

图4 盈江MS5.8级地震烈度等震线图<br/>Fig.4 Isoseism of the intensity of the Yingjiang MS5.8 earthquake

图4 盈江MS5.8级地震烈度等震线图
Fig.4 Isoseism of the intensity of the Yingjiang MS5.8 earthquake

表3 震源机制解<br/>Tab.3 Focal mechanism solution

表3 震源机制解
Tab.3 Focal mechanism solution

图5 盈江MS5.8级地震震源机制解(a)本文的结果;(b)中国地震局地球物理研究所的结果;(c)美国USGS的结果<br/>Fig.5 Focal mechanism solution of the Yingjiang MS5.8 earthquake(a)Got by author;(b)Referred from the institute of Geophysics,CEA;(c)Referred from USGS

图5 盈江MS5.8级地震震源机制解(a)本文的结果;(b)中国地震局地球物理研究所的结果;(c)美国USGS的结果
Fig.5 Focal mechanism solution of the Yingjiang MS5.8 earthquake(a)Got by author;(b)Referred from the institute of Geophysics,CEA;(c)Referred from USGS

图6 盈江震区周边地区P轴方位角<br/>Fig.6 Azimuth of P-axis in Yingjiang and its surrounding area

图6 盈江震区周边地区P轴方位角
Fig.6 Azimuth of P-axis in Yingjiang and its surrounding area

图7 盈江震区周边地区压应力(a)及震源机制解(b)<br/>Fig.7 Compressive stress(a)and mechanism(b)in Yingjiang and its surrounding area

图7 盈江震区周边地区压应力(a)及震源机制解(b)
Fig.7 Compressive stress(a)and mechanism(b)in Yingjiang and its surrounding area

图8 盈江地震前地震学参数时间异常指标(a)时间间隔Δt(M≥5);(b)能量释放E(M3.0～4.9); (c)地震力标度σ(M2.5～4.9)<br/>Fig.8 Anomalous indexes of time the seismological parameters before Yingjiang MS5.8 earthquake(a)Interval:Δt(M≥5);(b)Energy release:E(M3.0～4.9); (c)Seismic force scale σ(M2.5～4.9)

图8 盈江地震前地震学参数时间异常指标(a)时间间隔Δt(M≥5);(b)能量释放E(M3.0～4.9); (c)地震力标度σ(M2.5～4.9)
Fig.8 Anomalous indexes of time the seismological parameters before Yingjiang MS5.8 earthquake(a)Interval:Δt(M≥5);(b)Energy release:E(M3.0～4.9); (c)Seismic force scale σ(M2.5～4.9)