地震研究

结合波形互相关技术,运用双差定位方法对2014年景谷MS6.6地震及其强余震序列进行重定位。对序列中2.0≤ML≤5.0共730个事件重定位得到649个重定位结果。定位误差在EW向为18 m,NS向为19 m,深度方向为23 m。结果显示此次景谷地震序列主要沿2个优势方向展布:一个是主震发生后沿NW走向的无量山断裂西支(普文断裂)延长线呈长约20 km的带状分布,一个是12月6日MS5.8和MS5.9两个强余震发生后沿近NS向长度约10 km左右的展布,这可能与西侧的NNE走向的澜沧江断裂及东侧NW走向的无量山断裂西支(普文断裂)共同作用有关,也有可能是发震断层分段破裂或分段活动造成的结果。从深度上看,序列大部分地震集中分布在6～15 km深度范围内,而在12月6日强余震发生几天后,序列地震的深度有一个整体变深的趋势,分布范围主要集中在9～16 km,这与序列位置及走势发生变化有关,也提示了研究区域地质结构的复杂性。我们用全波形模拟法得到了序列中MS≥3.5地震震源机制解,主震北侧发生的地震,震源机制与主震一致性较好; 而主震南侧的地震,其震源机制解主破裂面走向有向NS向偏转的趋势。

Using the double-difference method that combined with waveform cross-correlation,we relocated the Jinggu MS6.6 and its 730 aftershocks with magnitude between 2 and 5 and finally obtained 649 relocated earthquakes,the statistical location error are 18 m in EW,19 m in NS and 23 m in depth direction,respectively.The aftershock sequence presents a zonal shape with lengths of 20km and along the west branch of Wuliangshan fault(Puwen fault).But two strong aftershocks sequence distribution direction has some transformation,mainly along the nearly NS with length of 10 km after the strong aftershocks with MS5.8 and MS5.9.This may be associated with fracture on the west side of NNE direction of the Lancang river fault and on the east side of NW direction of the west branch of Wuliangshan fault(Puwen fault),also may be related to segmental rupture or segmental activity of fault.Most earthquakes are predominately located between 6 km and 15 km.But the depth of the earthquake sequence has the tendency of a whole deeper distribution range are mainly concentrated in 9 km to 16 km a few days later.This indicates the complexity of the regional geological structure.Using full waveform simulation method to get the focal mechanism solution of MS≥3.5 earthquakes,the focal mechanism of the north earthquakes is consisted with the main shock.The strike of plane I of the south earthquakes have a trend towards NS.

引言
1 重定位方法和数据
2 重定位结果分析
3 震源机制解特征分析
4 结论

表1 一维P波速度模型<br/>Tab.1 1D velocity model by P wave

表1 一维P波速度模型
Tab.1 1D velocity model by P wave

图1 所选用的台站(a)及初步重定位结果(b)<br/>Fig.1 Stations used in relocation(a)and the preliminary relocated results(b)

图1 所选用的台站(a)及初步重定位结果(b)
Fig.1 Stations used in relocation(a)and the preliminary relocated results(b)

图2 景谷地震震后12小时内地震序列分布图(a)和震后85天地震序列分布图(b)<br/>Fig.2 Distributions of the Jigu earthquake sequence in 12 hours after the mainshock(a)and the sequence in 85 days after the mainshock(b)

图2 景谷地震震后12小时内地震序列分布图(a)和震后85天地震序列分布图(b)
Fig.2 Distributions of the Jigu earthquake sequence in 12 hours after the mainshock(a)and the sequence in 85 days after the mainshock(b)

图3 景谷地震序列重定位后深度沿不同剖面的分布<br/>Fig.3 Distribution of focal depth of the Jinggu earthquake sequence along the different profiles

图3 景谷地震序列重定位后深度沿不同剖面的分布
Fig.3 Distribution of focal depth of the Jinggu earthquake sequence along the different profiles

图4 重定位后2.0≤ML≤5.0地震序列深度随时间的分布<br/>Fig.4 Distribution of the focal depth changed with the 2.0≤ML≤5.0 earthquakes sequences during after relocations

图4 重定位后2.0≤ML≤5.0地震序列深度随时间的分布
Fig.4 Distribution of the focal depth changed with the 2.0≤ML≤5.0 earthquakes sequences during after relocations

表2 景谷序列中MS≥3.5地震的震源机制解<br/>Tab.2 The focal mechanism solutions of MS≥3.5 events in the Jinggu earthquake sequence

表2 景谷序列中MS≥3.5地震的震源机制解
Tab.2 The focal mechanism solutions of MS≥3.5 events in the Jinggu earthquake sequence

表3 不同机构给出的主震震源机制解结果<br/>Tab.3 The results of focal mechanisms by different organizations

表3 不同机构给出的主震震源机制解结果
Tab.3 The results of focal mechanisms by different organizations

图5 景谷序列MS≥3.5地震震源机制解<br/>Fig.5 The focal mechanism solutions of MS≥3.5 earthquakes in the Jinggu earthquake sequence

图5 景谷序列MS≥3.5地震震源机制解
Fig.5 The focal mechanism solutions of MS≥3.5 earthquakes in the Jinggu earthquake sequence

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备注

引言

1 重定位方法和数据

2 重定位结果分析

3 震源机制解特征分析

4 结论

期刊信息