Research on the Repositioning and Seismic Source Characters of the Changdao Coastal Earthquake Sequences, Shandong Province
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摘要: 基于山东数字化地震台站的震相资料和胶东半岛地区的速度结构模型，利用双差定位方法对2017年2月14日开始的山东长岛地区双震群进行重新定位，结果显示主震群余震序列分布沿一级断裂分布，震群位置比较集中。并利用CAP方法（Cut and Paste）对长岛海域2个震群中的几个较大地震进行震源机制解的反演分析，其中，2017年3月3日的主震震源机制解的节面Ⅰ走向为320°，倾角57°，滑动角为12°；节面Ⅱ走向为223.4°，倾角80°，滑动角为146.4°；主震的最佳拟合深度在9.7km，6次较大地震的节面Ⅰ走向也基本一致。Abstract: Based on the data collected by the Shandong Digital seismic Network and the speed-structure model, we use the accurate double-difference location method to relocate two sequences starting from the February 14, 2017, the result show that the distribution of the aftershocks of the main sequence is along the class-Ⅰ fault in earthquake swarm, In this paper also applied the CAP method to analyze inversely the focal mechanism solutions of several earthquake in the Changdao costal area. The focal mechanism solution of the main earthquake on March 3, 2017 includes the flowing parameters:nodal plane Ⅰ (trend of 320°, dip angle 57° and slide angle 12°); plane Ⅱ (trend of 223.4°, dip angle 80° and slide angle 146.4), The optimum fitting depth is 9.7km The solutions of nodal plane of these six large earthquakes agree with each other well.
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Key words:
- Changdao /
- Accurate double-difference location /
- CAP /
- Focal mechanism solution
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图 1 长岛地震序列附近断层和台阵台站分布
Figure 1. Distribution of faults and stations around the the Changdao earthquake sequence
图 3 长岛海域震群P和S波走时曲线
Figure 3. The travel time curves of P wave and S wave of Changdao earthquake sequence
图 4 长岛海域震群折合走时曲线
Figure 4. The reduced travel-time curves of the Changdao earthquake sequence
图 5 长岛地震序列双差定位前后频次-深度分布关系
Figure 5. Distriution of earthquake depth and frequency before and after the accurate location of the Changdao earthquake sequence
图 6 长岛海域震群震中分布及震源深度统计
Figure 6. The statistical distribution and focal depth of the Changdao earthquake epicenter
图 7 长岛4.4级地震理论地震图和观测地震图对比（a）和CAP方法的最佳拟合深度和波形拟合图（b）
Figure 7. The comparison of theoretical seismogram and observation seismogram of the Changdao M 4.4 earthquake (a) and plot of focal depth varying with different depth errors and focal mechanism (b)
表 1 地壳速度模型
Table 1. Crustal velocity model
深度/km vp/km·s-1 vs/km·s-1 22 6.13 3.54 33 6.88 3.98 70 7.93 4.58 
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表 2 长岛海域震群序列6次较大地震震源机制解
Table 2. Focal mechanisms of six larger earthquake in the Changdao earthquake sequences
发震时间 东经/° 北纬/° 震级 节面Ⅰ/° 节面Ⅱ/° 最佳拟合
震源深度/km走向 倾角 滑动角 走向 倾角 滑动角 2017-03-03
02:48120.8056 38.1051 4.4 320 57 12 223.4 80 146.4 9.7 2017-03-21
00:54120.7839 38.1014 3.9 321 53 -10 57.1 82 -142.6 10.1 2017-03-27
22:06120.7721 38.1050 4.1 321 50 161 63.5 75.6 41.6 8.7 2017-04-08
02:08120.8051 38.1032 4.0 323 63 0 233 90 153 9.8 2017-04-08
07:44120.7897 38.1012 3.7 351 60 -57 118.6 43.4 -133.3 13.7 2017-06-18
16:33120.7899 38.0955 4.0 331 55 -12 61 90 -143.2 10.7
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