| 汶川、芦山地震前龙门山断裂带地壳形变特征对比分析 |
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| 关键词:Wenchuan earthquake Lushan earthquake Longmen Shan fault zone three-dimensional deformation seismic risk |
| 基金项目:国家重点研发计划项目(编号: 2017YFC1500502);国家自然科学基金项目(编号: 11672258) |
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| 摘要: |
| A Contrastive Analysis of Crustal Deformation Characteristics along the Longmen Shan Fault Zone before the MS8.0 Wenchuan Earthquake and the MS7.0 Lushan Earthquake |
| To contrastively analyze crustal deformation characteristics before the Wenchuan earthquake and the Lushan earthquake, the authors mainly used four periods GPS velocity during 1999–2015 and cross fault short leveling data during 1990–2017 to analyze the GPS velocity profiles across the fault, the GPS strain rate field, fault locking and slip deficit rate, annual vertical change rate in detail, and summarized evolution characteristics of three-dimensional crustal deformation along the Longmen Shan fault zone before and after the Wenchuan and the Lushan earthquake. The results show that the mid-northern segment of the Longmen Shan fault zone was locked tightly and stress and strain accumulation level of fault plane was very high before the Wenchuan earthquake, while the southwestern segment was locked weakly, deformation rate was significantly higher than that of the mid-northern segment, and it still could accumulate stress and strain. In addition, the source of the Wenchuan earthquake was located in relatively weakly locked position, which probably led the Wenchuan earthquake to rupture unilaterally since the initial rupture point and the southwestern segment didn’t rupture. The Wenchuan earthquake accelerated stress and strain accumulation rate of the southwestern segment and increased fault locking degree and locking area, which might, to some extent, have accelerated the Lushan earthquakes. And source of the Lushan earthquake was located in high gradient transition sites of strongly and weakly locked position before the Wenchuan earthquake. Because the Lushan earthquake only released finite strain energy of the southwestern segment of the Longmen Shan fault zone, and it did not significantly reduce seismic hazard in the segment, researchers therefore should pay attention to the earthquake empty segment between the Wenchuan earthquake and the Lushan earthquake and the segment southwest of the Lushan earthquake. In addition, the authors collected and contrastively analyzed crustal deformation characteristics before multiple earthquakes of magnitude 6 to 9, and the results also show that the earthquake nucleation was in the area of highly locked gradient zone rather than the completely locked zone, and the length of the locked fault surface increased with the increasing magnitude, which requires us to conduct in-depth research and analysis with the help of high-resolution deformation data. |
| ZHAO Jing,LIU Jie,REN Jin-wei,JIANG Zai-sen,YAN Wei,YUE Chong.2019.A Contrastive Analysis of Crustal Deformation Characteristics along the Longmen Shan Fault Zone before the MS8.0 Wenchuan Earthquake and the MS7.0 Lushan Earthquake[J].Acta Geoscientica Sinica,40(1):186-198. |
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