Timing and seismic origin of Nixu rock avalanche in southern Tibet and its implications on Nimu active fault
Timing and seismic origin of Nixu rock avalanche in southern Tibet and its implications on Nimu active fault
复制标题
藏南尼须岩崩的时代、地震成因及其对尼木活动断裂的意义
DOI：
10.1016/j.enggeo.2020.105522
复制
发表时间：
2020
影响因子：
7.4
通讯作者：
Liye Liao
中科院分区：
文献类型：
--
作者：
Qingli Zeng;Rongqiang Wei;Hua Du;Fengshan Ma;Guangxiang Yuan;Mauri McSaveney;Liye Liao
在构造活跃区，大型滑坡的识别、定年和成因确定对于识别区域断层的地震活动性和地震震级、重建史前景观演变和估计地震危险性具有重要意义。研究表明：(1)深部泥徐岩崩横跨尼木活动正断层向鞍钢盆地扩散，沉积体积为47 mm3，移动距离为4960 m。(2)沿天然河流侵蚀剖面的崩岩沉积物下的腐殖质样品表明，NXRA事件的14c年龄为820±30 BP（1220±30 CalAD）。(3)识别出23个相邻滑坡具有聚类与距离效应、脊端放大效应和坡向效应等同震分布特征。在离雪崩沉积物约300 m处的基底上发现了砂土液化和泥炭变形。(4)根据Keefer（1994）和Wells & Coppersmith（1994）的经验方程估计，1264年发生的里氏mw7.0 - 7.2级地震很可能触发了NXRA。认为亚东-古鲁裂谷的尼木断裂易发生大型同震滑坡，其危险性可能高于南北两部分。
In tectonically active mountain areas, the identification, dating and determination of origin of large landslides are of special importance in recognizing the seismicity and earthquake magnitude of regional faults, reconstructing the prehistoric landscape evolution and estimating the seismic hazards. Based on field survey, high-resolution satellite image interpretation and14C dating of substrate, this paper studied the large, long-runout Nixu rock avalanche (the NXRA) in the Angang graben of the southern Tibetan Plateau. The study revealed that: (1) the deep-seated Nixu rock avalanche straddles the Nimu active normal fault and spreads onto the Angang basin with a deposit volume of 47 Mm3and a travelling distance of 4960 m. (2) Humus samples immediately under the deposit of rock avalanche along the natural river-erosion section suggest a14C age of 820 ± 30 BP (1220 ± 30 CalAD) for the NXRA event. The age well matches the 1264 CE Chubushi earthquake recorded in Tibetan documents. (3) 23 adjacent landslides have been recognized with co-seismic distribution features, such as clustering and distance effect, ridge-end amplification effect and slope aspect effect. Sand liquefaction and peat deformation were discovered in the substrate beneath and at a distance of ~300 m away from the avalanche deposit. (4) This information indicate that the NXRA was triggered most likely by the 1264 Chubushi earthquake with a magnitude ofMw7.0–7.2 estimated by empirical equations of Keefer (1994) and Wells & Coppersmith (1994). It is suggested that the Nimu fault of the Yadong-Gulu rift may be more hazardous than the northern and southern part due to its high susceptibility of large co-seismic landslides.