地震研究

利用1970年1月至2018年10月吴忠—灵武地区的地震精定位目录,基于b值平面分布以及沿活动断裂的震源深度剖面和b值剖面图等,分析了研究区发生强震的潜在危险性。结果表明:①新华桥附近存在发生地震的潜在危险性,强度为MS5.1～5.4,但b值时序曲线表明该区域短期内发生中强地震的紧迫性不强; ②吴忠/郭家桥—高闸地区很可能是1921年2月22日吴忠南MS6.0地震的发震位置,该地震震源深度应在15 km左右,上地壳浅部很可能未破裂; ③吴忠/郭家桥—高闸地区地壳浅部依旧存在发生强震的危险,孕震强度为MS6.2～6.3,孕震深度在10 km以内。

In the paper,we relocated the earthquakes in Wuzhong-Lingwu region from Jan.,1970 to Oct.,2018 based on Hypo2000 and HypoDD methods.Then,analyzing the horizontal distribution of b-value,focal depth profile and b-value profile along active fault,we studied the potential risk of strong earthquakes in the study region.The results show that:① There is a risk of MS5.1～5.4 earthquakes near Xinhuqiao area.However,the b-value time series curve does not support the occurrence of medium-strong earthquakes in the region in a short time.② The Wuzhong MS6.0 earthquake on Feb.22,1921 is likely to occur in Wuzhong-Gaozha region.The focal depth of the earthquake is about 15 km,and the shallow part of the upper crust is probably unbroken.③ There is still a risk of strong earthquakes with MS6.2～6.3 in the shallow crust of the Wuzhong-Gaozha region and the focal depth is within 10 km.

引言
1 资料选取
2 结果分析
3 讨论
4 结论

图1 研究区位置、构造背景及地震分布(1970年1月—2018年10月)<br/>Fig.1 Location of research area and distribution of tectonic background and earthquakes from Jan.,1970 to Oct.,2018

图1 研究区位置、构造背景及地震分布(1970年1月—2018年10月)
Fig.1 Location of research area and distribution of tectonic background and earthquakes from Jan.,1970 to Oct.,2018

图2 1970年1月—2018年10月研究区ML≥0 地震M-T(a)、N-T(b)和M-N图(c)<br/>Fig.2 M-T(a),N-T(b)and M-N(c)diagrams of the ML≥0 earthquakes from Jan.,1970 to Oct.,2018

图2 1970年1月—2018年10月研究区ML≥0 地震M-T(a)、N-T(b)和M-N图(c)
Fig.2 M-T(a),N-T(b)and M-N(c)diagrams of the ML≥0 earthquakes from Jan.,1970 to Oct.,2018

图3 b值随震级的变化<br/>Fig.3 b-value changes with magnitude

图3 b值随震级的变化
Fig.3 b-value changes with magnitude

图4 研究区地震震级-频度关系曲线(1970年1月—2018年10月)<br/>Fig.4 Magnitude-frequency curve of earthquakes in the study area from Jan.,1970 to Oct.,2018

图4 研究区地震震级-频度关系曲线(1970年1月—2018年10月)
Fig.4 Magnitude-frequency curve of earthquakes in the study area from Jan.,1970 to Oct.,2018

图5 研究区地震密度分布<br/>Fig.5 Distribution of seismicity density in the study area

图5 研究区地震密度分布
Fig.5 Distribution of seismicity density in the study area

图6 研究区中部地震集中区b值时间进程曲线<br/>Fig.6 Curve of b-value in the seismic concentration area in the middle of the study area

图6 研究区中部地震集中区b值时间进程曲线
Fig.6 Curve of b-value in the seismic concentration area in the middle of the study area

图7 研究区b值平面分布<br/>Fig.7 Horizontal distribution of b-value in the study area

图7 研究区b值平面分布
Fig.7 Horizontal distribution of b-value in the study area

图8 沿断裂方向的地震深度剖面(a)和b值剖面分布(b)(剖面位置见图 1)
Fig.8 Depth profile(a)and b-value profile(b) along the active fault(profile location is shown in Fig.1)

图9 研究区MC空间分布<br/>Fig.9 Spatial distribution of MC-value in the study area

图9 研究区MC空间分布
Fig.9 Spatial distribution of MC-value in the study area

图10 不同扫描半径所占节点的比例数<br/>Fig.10 Proportion of nodes with different search radius

图10 不同扫描半径所占节点的比例数
Fig.10 Proportion of nodes with different search radius

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备注

引言

1 资料选取

2 结果分析

3 讨论

4 结论

期刊信息