| 青藏高原东南缘滇缅地块NE向走滑断裂带的新构造活动与大地震危险性 |
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| 引用本文： | 刘鸣,付碧宏,董彦芳.青藏高原东南缘滇缅地块NE向走滑断裂带的新构造活动与大地震危险性[J].地球物理学报,2015,58(11):4174-4186. |
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| 作者姓名： | 刘鸣 付碧宏 董彦芳 |
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| 作者单位： | 1. 中国科学院地质与地球物理研究所, 北京 100029;
2. 中国科学院遥感与数字地球研究所, 北京 100094;
3. 中国科学院大学, 北京 100049;
4. 中国地震局地震预测研究所, 北京 100036 |
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| 基金项目： | 中国地震活断层探察-南北地震带中南段(201108001)和中国科学院战略先导专项(B)"深部-浅部相互作用及远程效应"项目(XDB03020200)共同资助. |
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| 摘 要： | 2008年汶川大地震发生以来,位于青藏高原东南缘实皆断裂带和红河断裂系之间滇缅地块发生了一系列MS5.5以上中强地震,该地区未来是否可能发生MS7.0以上大地震的危险性,十分令人关注.本研究以滇缅地块内部最长的NE向走滑断裂带——南汀河断裂带为例,结合遥感图像、数字高程模型(DEM)和1∶20万地质图,对断裂带附近的水系系统拐弯地貌特征和大型地质体单元位错信息进行提取分析,并根据这些断裂带左旋走滑起始年代(5 Ma),推算其长期走滑速率.研究结果表明研究区NE向断裂带自上新世以来,具有2mm·a-1的长期走滑速率;此外,根据发生在断裂带上及其周边地区的历史地震、大震复发周期和区内现代构造应力场的分布分析发现,沿这些NE向大型左旋走滑断裂带未来具有MS7.0以上大地震发生的危险性.
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| 关 键 词： | 走滑断裂带 长期走滑速率 地震危险性 滇缅地块 青藏高原东南缘 |
| 收稿时间： | 2015-05-15 |
Neotectonics of NE-striking fault zones and earthquake risk in the Yunnan-Myanmar block,southeastern margin of the Tibetan plateau |
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| LIU Ming,FU Bi-Hong,DONG Yan-Fang.Neotectonics of NE-striking fault zones and earthquake risk in the Yunnan-Myanmar block,southeastern margin of the Tibetan plateau[J].Chinese Journal of Geophysics,2015,58(11):4174-4186. |
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| Authors: | LIU Ming FU Bi-Hong DONG Yan-Fang |
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| Institution: | 1. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;
2. Key Laboratory of Digital Earth Sciences, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100094, China;
3. University of Chinese Academy of Sciences, Beijing 100049, China;
4. Institute of Earthquake Science, China Earthquake Administration, Beijing 100036, China |
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| Abstract: | The Yunnan-Burma block, located in the southeast margin of the Tibetan plateau, is one of the most tectonically active regions in mainland China. Since 1900, more than 10 earthquakes with magnitude over 7 occurred in this region, which account for more than a half of the great earthquakes in Yunnan. Moreover, the recent MS7.2 earthquake occurred in Mong Hpayak on March 24, 2011, and a series of MS5.5 earthquakes in the western Yunnan. If these earthquakes are not isolated, does they mean early warning of great earthquakes in the future? Therefore, for the purpose of earthquake prevention and disaster mitigation, it is urgent and necessary to carry out seismic risk assessment in this region especially along the NE-trending fault zones.The method of tectonic geomorphology was used to analyze fault activity. By measuring the deformation of the typical geomorphic or geologic units together with dating data, fault activity was estimated. The measurement was finished indoor or in the field. Remote sensing data were interpreted and geologic maps were prepared. According to the interpretation of drainage systems based on the remote sensing data, displacement of faults were determined. In the field, the rope and scale were employed for measurement (if displacement is too long, GPS equipment was used). Using dating technology, motion rates on the faults in the study area were estimated. The analysis of tectonic geomorphology along the Nanting fault zone, and drainages and channels across the fault zone shows systematically left-lateral offset. The largest offset occurs along the Nujiang River, and total displacement of the fault here is about 10 km. Moreover, offsets of rivers near the village Datianba range from 1.5 to 5.5 km and 1.8 to 2.1 km near Panhe Farm, respectively. Besides geomorphic units, geologic units are also displaced. Granite bodies west of the Yun County show obviously sinistral slip ranging from 4.1m to 5.6 km.Based on the tectonic characteristics and deep dynamic mechanism of NE-trending tectonics within the Yunnan-Myanmar block, the following conclusions are obtained. Firstly, the maximum displacement of the NE-trending left lateral strike-slip fault zone is 10 km. According to its initial age of 5 Ma, the minimum of the left lateral strike slip rate is ca. 2 mm·a-1. Secondly, the late Cenozoic tectonic deformation and seismic activity of the Yunnan-Myanmar block are mainly controlled by the East India plate subduction, and the deformation in dominated by strike slip on faults. Thirdly, based on the analysis of the scales of NE direction left-lateral faults and recurrence times of historical earthquakes, the study region including the Nantinghe, Wanding and Dayingjiang fault zones and the surrounding areas has risk of large earthquakes of magnitude 7 or greater. More attention should be paid to earthquake prevention and risk assessment of large engineering projects in this region. |
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| Keywords: | Strike-slip fault Long-term slip rate Earthquake risk The Yunnan-Myanmar block Southeastern margin of Tibetan plateau |
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