| 川滇菱形块体东边界现今应变积累特征及强震危险性 |
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| 引用本文： | 刘辛中,张风霜,马伶俐,李腊月.川滇菱形块体东边界现今应变积累特征及强震危险性[J].大地测量与地球动力学,2022,42(7):687-693. |
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| 作者姓名： | 刘辛中 张风霜 马伶俐 李腊月 |
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| 摘 要： | 基于川滇地区2013~2018年GNSS速度场结果，解算区域地表应变率场，分析川滇菱形块体东边界现今地表应变特征，反演其断层闭锁程度和滑动亏损分布，并重点分析芦山地震后该区域的深部应变积累程度。结合已有历史地震破裂及断层库仑应力结果，综合分析芦山地震后川滇菱形块体东边界不同段的强震危险性。结果表明，川滇菱形块体东边界现今呈现出明显的左旋应变积累特征，三岔口地区剪切应变积累速率最大，最大量值为3.5×10-8/a；同时，川滇菱形块体东边界还表现出NS-NE向的拉张和近EW-NW向的挤压变形，康定-石棉段EW向挤压应变率最高，为-3×10-8/a；安宁河-则木河断裂带EW向挤压应变率为-2×10-8/a ~ -3×10-8/a，而小江断裂带由北至南挤压变形逐渐减缓，东川以南转为拉张变形；断层闭锁反演结果与GNSS应变率结果具有较好的一致性，同样反映出川滇菱形块体东边界左旋剪切应变兼局部挤压或拉张的应变积累特征。综合分析认为，鲜水河断裂带道孚-八美段、康定以南的磨西至安宁河断裂带及小江断裂带的巧家-东川段、宜良-建水段具有较高的闭锁程度和左旋滑动亏损速率，是强震危险性较高的段落。
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| 关 键 词： | 川滇菱形块体东边界 GNSS 断层闭锁 滑动速率亏损 应变积累 |
Current Strain Accumulation Characteristics and the Risk of Strong Earthquakes on the Eastern Boundary of the Sichuan-Yunnan Block |
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| LIU Xinzhong,ZHANG Fengshuang,MA Lingli,LI Layue.Current Strain Accumulation Characteristics and the Risk of Strong Earthquakes on the Eastern Boundary of the Sichuan-Yunnan Block[J].Journal of Geodesy and Geodynamics,2022,42(7):687-693. |
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| Authors: | LIU Xinzhong ZHANG Fengshuang MA Lingli LI Layue |
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| Abstract: | Based on the GNSS velocity field from 2013 to 2018 in the Sichuan-Yunnan region, we calculate the regional strain rate fields, and analyze the current strain accumulation rates distribution of the eastern boundary of the Sichuan-Yunnan block. We then invert the degree of fault locking and slip-rate deficit on the eastern boundary of the Sichuan-Yunnan block, focusing on the analysis of the strain accumulation characteristics in the deep depth of the eastern boundary of the Sichuan-Yunnan block after the Lushan earthquake. Finally, combined with the results of historical earthquake rupture and fault Coulomb stress, we comprehensively analyze the risk of strong earthquakes in different segments of the eastern boundary of the Sichuan-Yunnan block. The results show that the eastern boundary of the Sichuan-Yunnan block presents obvious characteristics of left-lateral strain accumulation; the shear strain accumulation rate in the Sanchakou area is the largest, with a maximum value of 3.5×10-8/a. Moreover, the eastern boundary of the Sichuan-Yunnan block also exhibits NS-NE directed extension and EW-NW directed compression deformation. The Kangding-Shimian segment has the highest EW-NW compression strain rate of -3×10-8/a. The Anninghe-Zemuhe fault zone also exhibits E-W-directed compression; the E-W-directed compression strain rate is -2×10-8/a to -3×10-8/a, while the compression deformation of the Xiaojiang fault zone gradually slows down from north to south and turns into tensile deformation near the south of Dongchuan. The fault-coupling inversion results are consistent with the GPS strain rate results, and reflects the left-lateral shear strain and local compression or tensile strain accumulation characteristics of the eastern boundary of the Sichuan-Yunnan block. Comprehensive analysis shows that the Daofu-Bamei segment, the Moxi segment of the Xianshuihe fault zone, the Anninghe fault zone, and the Qiaojia-Dongchuan and Yiliang-Jianshui segments of the Xiaojiang fault zone currently have a high locking degree and a left-lateral slip rate deficit, resulting in high potential for the next strong earthquake. |
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| Keywords: | the eastern boundary of Sichuan-Yunnan block GNSS fault locking slip rate deficit strain accumulation rate |
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