Distribution pattern of coseismic landslides triggered by the 2014 Ludian, Yunnan, China Mw6.1 earthquake:special controlling conditions of local topography
Distribution pattern of coseismic landslides triggered by the 2014 Ludian, Yunnan, China Mw6.1 earthquake:special controlling conditions of local topography
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2014年云南鲁甸Mw6.1地震引发的同震滑坡分布规律:当地地形的特殊控制条件
DOI：
10.1007/s10346-015-0641-y
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发表时间：
2015
期刊：
影响因子：
6.7
通讯作者：
陈晓利
中科院分区：
文献类型：
--
作者：
陈晓利
2014年云南鲁甸Mw6.1地震触发的同震滑坡的分布呈现出特殊的模式。它们并不沿断层线性地沿着集中（例如，发震断层）或构造带，而多在主震震中的东南、西部相对成簇地出现，相距5-9 km。其中绝大多数发生在悬崖峭壁的河段，如九龙江北岸红石岩村特大滑坡。这一现象表明，鲁甸地震同震滑坡的分布可能受河谷局部地形条件的控制。为了定量验证这一直观的推测，本研究提出了一个参数的相对滑坡面积比，与当地地形条件的滑坡面积比进行了统计。结果表明，该比值与三个地形变量高度相关，即，坡度角、局部起伏和坡面（面向斜坡的方向）。研究区同震滑坡多发生在坡角大于30° ~ 40 °的地段，尤其是坡角大于50°的河段。滑坡的局部分布与地形起伏呈正相关，绝大多数滑坡位于高差大于400 m的地方。顺南和东南向边坡最易发生同震滑坡，这可能与主震过程中发震断层由北西向东南、由深向浅破裂有关。这也可能是由于震中西南方向没有同震滑坡，但也存在陡坡河段的原因。这意味着震源过程可以对当地地形条件对地震诱发滑坡分布格局的控制构成制约。
The distribution of coseismic landslides triggered by the 2014 Ludian, Yunnan, China Mw6.1 earthquake exhibits a particular pattern. They do not concentrate linearly along a fault (e.g., the causative fault) or a tectonic zone, instead mostly appear in the southeast and west of the epicenter of the main shock in a relatively clustering manner, 5–9 km distant. Majority of them occur at the river reaches with cliffs, including the unusually large-scale landslide at the Hongshiyan village, north bank of the Njiulanjiang River. Such a phenomenon implies that local conditions of terrain of the river valley might control the distribution of coseismic landslides induced by the Ludian event, which is of a moderate magnitude. To verify quantitatively this intuitive conjecture, this study proposes a parameter of the relative landslide area ratio, with which a statistics is made for landslide area ratios and local terrain conditions. The results demonstrate that this ratio value is highly correlated with the three terrain variables, i.e., slope angle, local relief, and slope aspect (facing direction of the slope). In the study area, most coseismic landslides occur at loci with slope angle greater than 30°–40°, particularly the river reaches with slope angle exceeding 50°. Localized distribution of the landslides is positively correlated with terrain relief, of which majority lies at places with altitude differences over 400 m. The side slopes facing south and southeast are most prone to occurrence of coseismic landslides, which may be explained by the mainshock process that the seismogenic fault ruptured from northwest to southeast and from deep to shallow. It may also be an account on which there is no coseismic landslide southwest of the epicenter, though there also exist river reaches with steep slopes. It means that the seismic source process can pose a constraint on the control of local terrain conditions on the distribution pattern of earthquake-induced landslides.