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Probabilistic mapping of earthquake-induced submarine landslide susceptibility in the South-West Iberian margin
Marine Geology ( IF 2.6 ) Pub Date : 2020-07-22 , DOI: 10.1016/j.margeo.2020.106296
Stefano Collico , Marcos Arroyo , Roger Urgeles , Eulàlia Gràcia , Marcelo Devincenzi , Norma Peréz

The SW Iberian continental margin is well recognized as a tectonically active area, where major canyons and mass wasting events are both present. Earthquake triggered submarine landslides may cause tsunami and result in catastrophic damage to bordering coastal areas. In this setting, submarine landslide susceptibility mapping represents a major step towards a regional risk mitigation strategy. Landslide susceptibility mapping in large offshore areas presents significant challenges as a result of the limited information on controlling variables, large uncertainties in triggering mechanisms and limited geotechnical data. In this study, a geotechnical model-based approach has been followed that narrows the range of controlling factors and, within a probabilistic framework, allows a systematic treatment of parameter uncertainties. This model-based analysis covers the whole SW Iberian margin increasing by three orders of magnitude the areal extent of precedent offshore slope stability susceptibility studies. This jump in spatial scale is facilitated by application of a systematic Bayesian updating procedure, to combine geotechnical information from global databases and that available from regional sites. Seismic shaking is estimated using an available regional database of seismogenic faults. These tools are implemented within a GIS to generate, via Montecarlo simulations, probabilistic landslide susceptibility maps based on two different analytical seismic infinite slope stability models. These models differ mainly in the form of their final results, either as distributions of slope stability safety factors or as distributions of seismic-triggered slope displacements. Receiving Operator Curves are used to assess the different landslide susceptibility predictions obtained against a comprehensive regional database of submarine landslides. It turns out that the models analyzed correctly predict 92% and 82% of the mapped landslide subset chosen for validation for pseudo-static and displacement-based method respectively. This suggests that, within the limits of the currently available databases, seismic events are the dominant factor at the origin of the submarine landslides mapped in the study area. An advantage of the framework presented is that it can quickly incorporate new regional geotechnical information or better regional landslide databases, as they become available.



中文翻译:

伊比利亚西南边缘地震诱发的海底滑坡敏感性的概率图

SW伊比利亚大陆边缘被公认是一个构造活跃的地区,那里同时存在主要的峡谷和大量的浪费事件。地震引发的海底滑坡可能引起海啸,并对毗邻的沿海地区造成灾难性破坏。在这种情况下,海底滑坡敏感性图代表了朝着区域风险缓解战略迈出的重要一步。由于控制变量信息有限,触发机制存在较大不确定性以及岩土工程数据有限,大型离岸地区的滑坡敏感性地图提出了重大挑战。在这项研究中,遵循了一种基于岩土模型的方法,该方法缩小了控制因素的范围,并且在一个概率框架内,允许系统地处理参数不确定性。西南伊比利亚边界的面积增加了三个数量级,这是先例的海上边坡稳定性敏感性研究的范围。通过应用系统的贝叶斯更新程序,将来自全球数据库的岩土信息与区域站点的岩土信息相结合,可以促进空间尺度的这种跳跃。使用可用的地震成因断层区域数据库来估计地震震动。这些工具在GIS中实现,可以通过蒙特卡洛模拟,基于两个不同的分析地震无限边坡稳定性模型,生成概率滑坡敏感性图。这些模型的主要不同之处在于其最终结果的形式,要么是边坡稳定性安全系数的分布,要么是地震触发的边坡位移的分布。接收算子曲线用于评估针对海底滑坡的综合区域数据库获得的不同滑坡敏感性。结果表明,所分析的模型正确地预测了分别为拟静力法和基于位移的方法验证而选择的映射滑坡子集的92%和82%。这表明,在当前可用数据库的限制内,地震事件是研究区域中海底滑坡起源的主要因素。所提出的框架的一个优点是,它可以迅速合并新的区域岩土工程信息或更好的区域滑坡数据库(如果有的话)。结果表明,所分析的模型正确地预测了分别为拟静力法和基于位移的方法验证而选择的映射滑坡子集的92%和82%。这表明,在当前可用数据库的限制内,地震事件是研究区域中海底滑坡起源的主要因素。所提出的框架的一个优点是,它可以迅速合并新的区域岩土工程信息或更好的区域滑坡数据库(如果有的话)。结果表明,所分析的模型正确地预测了分别为拟静力法和基于位移的方法验证而选择的映射滑坡子集的92%和82%。这表明,在当前可用数据库的限制内,地震事件是研究区域中海底滑坡起源的主要因素。所提出的框架的一个优点是,它可以迅速合并新的区域岩土工程信息或更好的区域滑坡数据库(如果有的话)。地震事件是研究区域内海底滑坡起源的主要因素。提出的框架的一个优点是,它可以迅速合并新的区域岩土技术信息或更好的区域滑坡数据库(如果有的话)。地震事件是研究区域内海底滑坡起源的主要因素。提出的框架的一个优点是,它可以迅速合并新的区域岩土技术信息或更好的区域滑坡数据库(如果有的话)。

更新日期:2020-07-22
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