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| 芦山地震发震构造及其与汶川地震关系讨论 | |
| 引用本文： | 徐锡伟,陈桂华,于贵华,程佳,谭锡斌,朱艾斓,闻学泽.芦山地震发震构造及其与汶川地震关系讨论[J].地学前缘,2013,20(3). |
| 作者姓名： | 徐锡伟 陈桂华 于贵华 程佳 谭锡斌 朱艾斓 闻学泽 |
| 作者单位： | 1. 中国地震局地质研究所活动构造与火山重点实验室,北京,100029 2. 上海市地震局,上海,201203 3. 四川省地震局,四川成都,610041 |
| 基金项目： | 国家自然科学基金项目，中国地震局芦山7.0级强烈地震科学考察项目 |
| 摘 要： | 芦山地震发生在巴彦喀拉块体与华南块体之间龙门山推覆构造带南段。野外考察表明,芦山地震在震中区没有形成具有构造地质意义的地震地表破裂带,仅在各山前陡坡地带出现平行于山麓陡坡的张性地裂缝、山地基岩崩塌、滑坡等边坡震动失稳现象和震动引起的砂土液化现象。重新定位的芦山地震余震分布、震源机制解和地表构造地质等分析表明,芦山地震的发震断层为一条现今尚未出露地表、其上断点仍埋藏在地下9km以下地壳中的一条盲逆断层,走向212°,倾向NW,倾角38°±2°,上断点以上至地表的构造变形符合断层扩展背斜模型。根据汶川地震和芦山地震的余震空间分布、地震破裂过程、深浅构造关系等差异反映出它们是分别发生在龙门山推覆构造带中段和南段的两次独立地震破裂事件。 |
| 关 键 词： | 芦山地震 龙门山推覆构造带 发震断层 断层扩展背斜 青藏高原 |
Seismogenic structure of Lushan earthquake and its relationship with Wenchuan earthquake |
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| Abstract: | The Lushan earthquake occurred on the southern segment of the Longmenshan thrust belt between the Bayan Har and south China blocks.Field investigations indicated that there is no any earthquake surface rupture zone generated by this earthquake,only secondary surface breaks,such as extensional ground fissures,landslides,bedrock collapses,and liquefactions were found in the epicentral areas,which were caused by slope instability and earthquake vibration.The relocated aftershocks,focal mechanism solutions and surface structural geology further demonstrate that the seismogenic fault of the Lushan earthquake is a blind reverse fault which strikes 212° and dips toward NW with a dip angle of 38°±2°.The upper tip of this blind reverse fault is still at the depth of about 9 km in the upper crust.The structural deformation from above the tip to the ground surface is in accordance with a fault-propagation-anticline model.Besides,the differences in spatial aftershocks' distribution,rupturing process and seismogenic structure suggest that the Wenchuan and Lushan earthquakes are two independent rupturing events occurred along the middle segment and southern segment of the Longmenshan thrust belt,respectively. |
| Keywords: | Lushan earthquake Longmenshan thrust belt seismogenic fault fault-propagation-anticline Tibetan Plateau |
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