多种方法测定2019年皎口水库地区2.5级以上地震震源深度

彭骁; 张蓓蕾

doi:10.19987/j.dzkxjz.2022-070

多种方法测定2019年皎口水库地区2.5级以上地震震源深度

doi: 10.19987/j.dzkxjz.2022-070

彭骁^,,
张蓓蕾

宁波地震监测预报中心，浙江宁波 315000

基金项目: 2020年度浙江省地震局局科技项目（2020zjj12）资助。

详细信息

通讯作者:
彭骁（1990-），男，助理工程师，主要从事地震监测预报相关研究。 E-mail：648666236@qq.com

中图分类号: P315.3⁺3
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出版历程
- 收稿日期: 2022-04-29
- 录用日期: 2022-09-14
- 网络出版日期: 2022-10-13

Focal depth determination of earthquakes with M≥2.5 in Jiaokou reservoir area in 2019 by multiple methods

Peng Xiao^,,
Zhang Beilei

Ningbo Earthquake Monitoring and Prediction Center, Zhejiang Ningbo 315000, China

摘要

摘要: 应用CAP方法、sPL深度震相方法和双差定位方法，对2019年M2.5以上皎口水库地区地震震源深度进行测定。通过CAP方法进行反演，计算出最佳震源机制解及震源深度；在震中距50 km左右的近台识别出清晰的sPL震相，运用频率—波速（F-K）方法画出各种震源深度的理论波形，与实际波形进行拟合确定震源深度；建立地震事件对，利用走时差观测值与理论值的残差确定其相对位置及深度。结果发现，上述多种方法测定的结果基本一致；相对而言，双差定位方法更适合皎口水库地区地震震源深度的测定。
- 震源深度 /
- CAP /
- sPL /
- 双差定位 /
- 震源机制
Abstract: In this paper, the focal depth of earthquakes with magnitude 2.5 or above in Jiaokou reservoir area in 2019 was determined using the CAP method, the sPL depth phase method and the double difference positioning method. The inversion is carried out by CAP method to calculate the optimal focal mechanism solution and focal depth. The clear sPL seismic phase is identified at the near station about 50 km away from the epicenter, the theoretical waveform of various focal depths is drawn using the frequency wave velocity (F-K) method, and the focal depth is determined through fitting with the actual waveform. The seismic event pair is established, and its relative position and depth are determined using the residual between the observed value and the theoretical value of travel time difference. The results of various methods are basically the same. In contrast, the double difference positioning method is more suitable for focal depth determination of earthquakes in Jiaokou reservoir area.
- focal depth /
- CAP /
- sPL /
- double difference positioning /
- focal mechanism

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图 1 台站和震中分布图

红色圆点表示震中；黑色三角表示所有提供数据资料的台站；红色三角表示参与CAP反演的台站；黑色粗实线代表省界；黑色细实线代表市界

Figure 1. Distribution of stations and epicenters

The red dot indicates the epicenter. The black triangles indicate all stations providing data. The red triangles indicate stations participating in CAP inversion. The black thick solid line represents the provincial boundary. The black thin solid line represents the city boundary

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图 2 基于CAP方法测定地震震源深度

（a）地震1震源深度拟合曲线；（b）地震1理论波形与观测波形拟合图，红色代表实际波形，黑色代表理论波形；（c）地震2震源深度拟合曲线；（d）地震2理论波形与观测波形拟合图；（e）地震3震源深度拟合曲线；（f）地震3理论波形与观测波形拟合图

Figure 2. Focal depth determination of earthquakes based on CAP method

(a) Focal depth fitting curve of Earthquake 1；(b) Fitting diagram of theoretical waveform and observed waveform of Earthquake 1, red represents actual waveform and black represents theoretical waveform；(c) Focal depth fitting curve of Earthquake 2；(d) Fitting diagram of theoretical waveform and observed waveform of Earthquake 2；(e) Focal depth fitting curve of Earthquake 3； (f) Fitting diagram of theoretical waveform and observed waveform of Earthquake 3

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图 3 sPL震相识别

红色代表R分量波形；绿色代表T分量波形；蓝色代表Z分量波形

Figure 3. sPL seismic phase identification

The red represents the R component waveform. The green represents the T component waveform. The blue represents the Z component waveform

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图 4 sPL三分向波形拟合

（a）地震1的R分量位移记录，黑色代表不同震源深度理论波形，红色代表台站实际波形；（b）地震1的T分量；（c）地震1的Z分量；（d）地震2的R分量；（e）地震2的T分量；（f）地震2的Z分量；（g）地震3的R分量；（h）地震3的T分量；（i）地震3的Z分量

Figure 4. sPL three phase waveform fitting

(a) R component of displacement record of Earthquake 1. The black represents the theoretical waveform of different focal depths, and the red represents the actual waveform of the station；(b) T component of Earthquake 1；(c) Z component of Earthquake 1；(d) R component of Earthquake 2；(e) T component of Earthquake 2；(f) Z component of Earthquake 2；(g) R component of Earthquake 3；(h) T component of Earthquake 3；(i) Z component of Earthquake 3

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图 5 地震序列双差定位前（a）后（b）震中分布图，AA′为拟合断层面

Figure 5. Epicenter distribution before （a） and after （b） double difference positioning of earthquake sequence sequence, AA′ is the fitting fault plane

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图 6 双差定位后地震震源深度剖面图

Figure 6. Seismic focal depth profile after double difference positioning

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表 1 皎口水库地区3次地震震源深度的测定结果

Table 1. Focal depth determination results of three earthquakes in Jiaokou reservoir area

地震序号	发震时刻（年-月-日时:分:秒）	震中位置		M	震源深度/km
地震序号	发震时刻（年-月-日时:分:秒）	北纬/°	东经/°	M	CAP	sPL	双差	台网
1	2019-05-28 10:44:51	29.833	121.260	3.0	6.1	5.0	5.9	6.0
2	2019-05-28 16:52:35	29.827	121.260	2.7	4.6	6.0	4.9	5.0
3	2019-05-29 19:03:00	29.831	121.256	2.7	6.6	6.0	6.1	6.0

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表 2 震中地区速度模型

Table 2. Velocity model of epicenter area

地层名称	地层厚度 /km	v_P /（km•s⁻¹）	v_S /（km•s⁻¹）	密度ρ /（kg•m⁻³）
软沉积层	0.50	2.50	1.20	2.10
上地壳	10.00	6.10	3.50	2.75
中地壳	10.00	6.30	3.60	2.80
下地壳	10.50	6.60	3.60	2.90
地幔	0.00	8.00	4.60	3.30

下载: 导出CSV

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