地震研究

利用云南地震台网观测资料,对2021年漾濞MS6.4地震序列的时空演化特征进行分析,结果表明:漾濞地震序列的空间展布可分为4段,且余震活动衰减非常迅速。通过分析历史地震序列类型、h值、等待时间法、累计频次曲线、初动方向等,判断漾濞MS6.4地震序列为前震-主震-余震型。利用云南地区6级地震最大余震发震时间统计和震级差分布特征分析,认为漾濞MS6.4地震最大余震已经发生。最后讨论了漾濞地震序列4级余震偏多的现象及可能的原因。

On the basis of the data of the 2021 Yangbi MS6.4 earthquake sequence recorded by the Yunnan Earthquake Observation Network,we analyze the temporal and spatial evolution characteristics of the sequence.The spatial distribution of the sequence can be divided into 4 sections and the aftershock-activity attenuate rapidly.Through the analysis of the type of the historical earthquake sequences in this area,the method of h-value,the method of dt-t,the method of the cumulative frequency,and first-motion signs of the earthquake wave,we determine that the Yangbi MS6.4 earthquake sequence belongs to foreshock-mainshock-aftershock type.According to the statistics of the original time of the historical strongest aftershocks in Yunnan,and the distribution characteristics of the magnitude differences,we conclude that the strongest aftershock of the Yangbi MS6.4 earthquake has occurred.Finally we discuss the high frequency of ML≥4.0 aftershocks in the sequence and the possible reasons.

引言
1 漾濞M_S6.4地震序列基本概况
2 漾濞M_S6.4地震序列时空统计特征
3 地震序列类型、强余震的早期趋势判断
4 讨论
5 结论

图1 漾濞MS6.4地震序列震中及其附近地震台站分布图<br/>Fig.1 Distribution of earthquake-monitoring stations around the epicenter of the Yangbi MS6.4 earthquake

图1 漾濞MS6.4地震序列震中及其附近地震台站分布图
Fig.1 Distribution of earthquake-monitoring stations around the epicenter of the Yangbi MS6.4 earthquake

表1 漾濞MS6.4地震序列目录(ML≥4.0)<br/>Tab.1 Catalogue of the Yangbi MS6.4 earthquake sequence(ML≥4.0)

表1 漾濞MS6.4地震序列目录(ML≥4.0)
Tab.1 Catalogue of the Yangbi MS6.4 earthquake sequence(ML≥4.0)

图2 漾濞MS6.4地震后24 h内震级-频度关系曲线<br/>Fig.2 Magnitude-frequency curve of earthquakes in 24 hours after the MS6.4 mainshock

图2 漾濞MS6.4地震后24 h内震级-频度关系曲线
Fig.2 Magnitude-frequency curve of earthquakes in 24 hours after the MS6.4 mainshock

图3 漾濞MS6.4地震序列最小完整性震级随时间变化<br/>Fig.3 MC-time curve of the YangbiMS6.4 earthquake sequence

图3 漾濞MS6.4地震序列最小完整性震级随时间变化
Fig.3 MC-time curve of the YangbiMS6.4 earthquake sequence

图4 漾濞地震序列重定位后的震中分布图<br/>Fig.4 Epicenter distribution of the relocated Yangbi earthquake sequence

图4 漾濞地震序列重定位后的震中分布图
Fig.4 Epicenter distribution of the relocated Yangbi earthquake sequence

图5 漾濞MS6.4地震前震序列M-t(a)和累计频度曲线(b)<br/>Fig.5 M-t curve(a)and cumulative number(b)of foreshocks before the Yangbi MS6.4 mainshock

图5 漾濞MS6.4地震前震序列M-t(a)和累计频度曲线(b)
Fig.5 M-t curve(a)and cumulative number(b)of foreshocks before the Yangbi MS6.4 mainshock

图6 漾濞MS6.4地震序列余震M-t(a)和日频度曲线(b)<br/>Fig.6 M-t(a)and daily frequency(b)of aftershocks of the Yangbi MS6.4 sequence

图6 漾濞MS6.4地震序列余震M-t(a)和日频度曲线(b)
Fig.6 M-t(a)and daily frequency(b)of aftershocks of the Yangbi MS6.4 sequence

图7 中甸—大理地震带历史地震序列类型分布图<br/>Fig.7 Sequence types in the Zhongdian-Dali earthquake zone

图7 中甸—大理地震带历史地震序列类型分布图
Fig.7 Sequence types in the Zhongdian-Dali earthquake zone

表2 维西—乔后断裂带附近历史地震序列类型<br/>Tab.2 Sequence types near the Weixi-Qiaohou fault

表2 维西—乔后断裂带附近历史地震序列类型
Tab.2 Sequence types near the Weixi-Qiaohou fault

图8 漾濞MS6.4地震序列h值<br/>Fig.8 h-value of the Yangbi MS6.4 earthquake sequence

图8 漾濞MS6.4地震序列h值
Fig.8 h-value of the Yangbi MS6.4 earthquake sequence

图9 漾濞MS6.4地震dt-t曲线(ML≥4.0)<br/>Fig.9 dt-t curve of the Yangbi MS6.4 earthquake sequence(ML ≥4.0)

图9 漾濞MS6.4地震dt-t曲线(ML≥4.0)
Fig.9 dt-t curve of the Yangbi MS6.4 earthquake sequence(ML ≥4.0)

图10 2021年5月21—28日漾濞MS6.4地震ML≥3.0地震序列累计频度曲线<br/>Fig.10 Cumulative frequency of the Yangbi MS6.4 earthquake sequence(ML≥3.0,21-28 May)

图10 2021年5月21—28日漾濞MS6.4地震ML≥3.0地震序列累计频度曲线
Fig.10 Cumulative frequency of the Yangbi MS6.4 earthquake sequence(ML≥3.0,21-28 May)

图11 岔河台(a)和团山台(b)记录的序列P波初动方向和S-P到时差<br/>Fig.11 Directions of P-wave first motion signs,time-diff.of S-wave recorded by CHT(a)and TUS(b)Stations

图11 岔河台(a)和团山台(b)记录的序列P波初动方向和S-P到时差
Fig.11 Directions of P-wave first motion signs,time-diff.of S-wave recorded by CHT(a)and TUS(b)Stations

表3 云南地区6.0～6.9级地震序列参数<br/>Tab.3 Parameters of the M6.0～6.9 earthquake sequences in Yunnan

表3 云南地区6.0～6.9级地震序列参数
Tab.3 Parameters of the M6.0～6.9 earthquake sequences in Yunnan

图12 云南地区6.0～6.9级地震最大余震发生时间统计<br/>Fig.12 Statistics of the occurrence time of the biggest aftershocks of the M6.0～6.9 mainshocks in Yunnan

图12 云南地区6.0～6.9级地震最大余震发生时间统计
Fig.12 Statistics of the occurrence time of the biggest aftershocks of the M6.0～6.9 mainshocks in Yunnan

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备注

引言

1 漾濞M_S6.4地震序列基本概况

2 漾濞M_S6.4地震序列时空统计特征

3 地震序列类型、强余震的早期趋势判断

4 讨论

5 结论

期刊信息

备注

引言