| 2010年以来四川地区中强地震震源机制反演及深度确定 |
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| 引用本文： | 赵博,高原,刘杰,梁姗姗,徐志国,杜广宝.2010年以来四川地区中强地震震源机制反演及深度确定[J].地球物理学报,2019,62(1):130-142. |
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| 作者姓名： | 赵博 高原 刘杰 梁姗姗 徐志国 杜广宝 |
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| 作者单位： | 1. 中国地震台网中心, 北京 100045;2. 中国地震局地震预测研究所, 北京 100036;3. 中国地震局地球物理研究所, 北京 100081;4. 国家海洋环境预报中心, 北京 100081 |
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| 基金项目： | 国家重点研发计划（2017YFC1500304）和地震监测重点专项（2018020110）联合资助. |
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| 摘 要： | 2008年5月12日四川龙门山断裂带发生了汶川8.0级地震,之后四川境内发生了两次7.0级地震(其中一个是芦山地震),为了研究汶川地震之后龙门山断裂带及周边区域的地震活动性,本研究收集了国家地震台网和四川区域地震台网2010年1月1日—2017年12月31日四川地区发生的17次M≥5.0地震以及120多次5.0>M≥4.0地震的波形资料,利用波形拟合法反演了震源机制解及区域应力场.反演结果显示,位于龙门山断裂带上的地震,震源机制以逆冲型为主,鲜水河断裂带地震震源机制以走滑型为主,而川滇块体西南部的理塘断裂、金沙江断裂附近,震源机制解以正断层为主.根据震源机制解反演得到的龙门山地区、鲜水河地区的主压应力场方向为WNW、近EW向.川滇块体的巴塘、理塘等地区,其主压应力轴方向为12°左右,接近SN向,且仰角接近40°左右.本研究利用面波振幅谱特征对震源深度进行了精确定位,定位结果与中国地震台网中心(CENC),美国地震调查局(USGS),国际地震中心(ISC)等机构地震目录进行了对比.结果显示,四川地区强震震源深度主要分布在20km以上的中上地壳.龙门山地区震源优势分布在10～20km,鲜水河断裂地震震源深度在10km左右,川滇块体西南部的理塘断裂,巴塘断裂,金沙江断裂等地区,震源深度一般在5～10km范围.
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| 关 键 词： | 四川地区 震源机制 震源深度 波形拟合法 面波振幅谱 |
| 收稿时间： | 2018-03-14 |
Focal mechanism inversion and source depth locating of moderate-major earthquakes in the Sichuan region since 2010 |
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| ZHAO Bo,GAO Yuan,LIU Jie,LIANG ShanShan,XU ZhiGuo,DU GuangBao.Focal mechanism inversion and source depth locating of moderate-major earthquakes in the Sichuan region since 2010[J].Chinese Journal of Geophysics,2019,62(1):130-142. |
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| Authors: | ZHAO Bo GAO Yuan LIU Jie LIANG ShanShan XU ZhiGuo DU GuangBao |
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| Institution: | 1. China Earthquake Networks Center, Beijing 100045, China;2. Institute of Earthquake Forecasting, China Earthquake Administration, Beijing 100036, China;3. Institute of Geophysics, China Earthquake Administration, Beijing 100081, China;4. National Marine Environmental Forecasting Center, Beijing 100081, China |
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| Abstract: | Focal mechanism solutions and accurate source depths of earthquakes are important for understanding seismicity and structure of seismic faults. This work collected the seismic wave data of earthquakes with magnitudes M ≥ 5.0 and 5.0 > M ≥ 4.0,which occurred from January 1, 2010 to December 31, 2017, recorded by the national seismic network and the regional seismic network in Sichuan province. The focal mechanisms of these events were inverted applying the synthetic seismograms method. The results show that the earthquakes on the Longmenshan fault zone are of thrust focal mechanism. On the Xianshuihe fault zone, focal mechanism solutions are dominated by strike-slip. And in the southwest of the Sichuan-Yunnan block, normal faulting dominates the focal mechanism solutions. As the excitation energy of surface waves is sensitive to source depth, the surface wave amplitude spectrum is applied to determine the focal depth and compared with the results from China Earthquake Networks Center (CENC), the U.S. Geological Survey (USGS), and the International Seismological Centre (ISC). The sources of the moderate-major earthquakes in the Sichuan region are mainly distributed in the upper-middle crust above 20 km. In the Longmenshan region, seismic sources are concentrated in the depth range from 10 km to 20 km. On the Xianshuihe fault zone, focal depths are confined about 10km. In the southwest of Sichuan-Yunnan block, near the Litang and Jinshajiang faults, the depths of seismic sources are generally 5 km to 10 km. |
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| Keywords: | Sichuan region Focal mechanism Focal depth Synthetic seismograms Surface wave amplitude spectrum |
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