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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Recurrent large-scale landsliding on the west flank of La Palma, Canary Island
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Recurrent large-scale landsliding on the west flank of La Palma, Canary Island

机译：加那利岛拉帕尔玛岛西侧经常发生大规模滑坡

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A large area of debris avalanche deposits has been discovered on the western submarine flanks of the island of La Palma. Multibeam bathymetry and its derivative backscatter data, Towed Ocean Bottom Instrument (TOBI) sidescan sonar images, and 3.5 kHz and airgun seismic reflection data have been used to identify at least two, and possibly as many as four, major landslide events. The youngest of the events, the Cumbre Nueva Debris Avalanche, extends onshore into the valleys bounded by the Caldera de Taburiente and Cumbre Nueva Ridge, which mark the degraded collapse scars. Radiometric dating of the volcanic flows in the hadwall indicate an age of between 536 and 125 ka for this landslide. The debris avalanche covers an area of 780 km~2, has a maximum thickness of 500 m, and has an estimated volume of 95 km~3. Older deposits, collectively referred to as the Playa de la Veta Devris Avalanche Complex, are probably, as the name indicates, an amalgamation of at least two or three events rather than the result of a single catastrophic failure. The playa de la Veta Debris Avalanche Complex is associated onshore with an unconformity dated as late Matuyama (1 Ma to 800 ka). It covers an area of 1200 km~2 has a maximum thickness of 1300 m, and may represent a total volume of up to 650 km~3. The greater thicknesses and limited areas occupied by debris avalanches on the western flank of La Palma, compared to other landslides in the Canary Archipelago, suggest that the La Palma landslide masses have relatively low mobility. The different debris avalanche lobes formed by each landslide event are separated by channels 2-2.5 km wide. THe clear relationship between channel position and the boundaries of each debris avalanche lobe indicates that debris avalanches control later channel formation and pathways. The relief of the submarine flanks of the La Palma volcanoes, in the areas of island slope unaffected by landslides, is mainly the result of constructional volcanic processes. However, the older submarine slopes, such as in the northern Taburiente volcano, may also have been modified by smaller-scale submarine mass wasting and sediment flows.
机译：在拉帕尔玛岛的西部海底侧面发现了大量的碎片雪崩沉积物。多波束测深及其派生的背向散射数据，拖曳海底仪器（TOBI）侧扫声纳图像以及3.5 kHz和气枪地震反射数据已被用来识别至少两个（可能多达四个）主要滑坡事件。其中最年轻的事件是Cumbre Nueva残骸雪崩，延伸至陆上由Caldera de Taburiente和Cumbre Nueva Ridge界定的山谷，这标志着退化的崩塌疤痕。辐射测量的火山墙中的火山流表明该滑坡的年龄介于536和125 ka之间。碎片雪崩的面积为780 km〜2，最大厚度为500 m，估计体积为95 km〜3。顾名思义，较旧的沉积物（统称为Playa de la Veta Devris雪崩综合体）可能至少合并了两个或三个事件，而不是一次灾难性失败的结果。 Playa de la Veta残骸雪崩综合体与陆上的不整合面相关，该不整合面可追溯到Matuyama晚（1 Ma至800 ka）。它的面积为1200 km〜2，最大厚度为1300 m，可能代表的总体积为650 km〜3。与加那利群岛的其他滑坡相比，拉帕尔玛岛西侧更大的厚度和被碎屑雪崩占据的区域有限，这表明拉帕尔玛滑坡体的流动性相对较低。每次滑坡事件形成的不同碎片雪崩裂片被2-2.5公里宽的河道隔开。通道位置与每个碎片雪崩裂片的边界之间的明确关系表明，碎片雪崩控制着后来的通道形成和路径。在不受滑坡影响的岛屿斜坡地区，拉帕尔玛火山海底侧面的浮雕主要是构造性火山作用的结果。但是，较旧的海底斜坡，例如北部塔布连特火山，也可能因规模较小的海底物质浪费和泥沙流而得到了改善。

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