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首页> 外文期刊>Natural hazards and earth system sciences >Rainfall-triggered landslides in the Lisbon region over 2006 and relationships with the North Atlantic Oscillation
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Rainfall-triggered landslides in the Lisbon region over 2006 and relationships with the North Atlantic Oscillation

机译：2006年里斯本地区降雨触发的滑坡及其与北大西洋涛动的关系

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摘要

Landslides occurred in the Lisbon area during the last 50 years were almost always induced by rainfall and have been used to establish rainfall thresholds for regional landslide activity. In 2006, three new rainfall-triggered landslide events occurred in the study area, namely on the 20 March, the 25-27 October, and the 28 November. Landslide events occurred in March and October 2006 include shallow translational slides and few debris flows, and the corresponding absolute antecedent rainfall was found to be above the threshold for durations ranging from 4 to 10 days. These events also fit the combined threshold of daily precipitation and 5 days calibrated antecedent rainfall values. Likewise the landslide event that took place in late November 2006 includes some slope movements with deeper slip surfaces, when compared with landslides dating from March and October. Moreover, the corresponding absolute antecedent rainfall was also found to be above the 40-day period rainfall threshold. Here we characterize in detail the short and long-term atmospheric circulation conditions that were responsible for the intense rainfall episodes that have triggered the corresponding landslide events. It is shown that the three rainfall episodes correspond to considerably different synoptic atmospheric patterns, with the March episode being associated to an intense cut-off low system while the October and November episodes appear to be related to more typical Atlantic low pressure systems (and associated fronts) travelling eastwards. Finally, we analyse the role played by the North Atlantic Oscillation (NAO) during those months marked by landslide activity. It is shown that the NAO index was consistently negative (usually associated with above average precipitation) for the months prior to the landslide events, i.e. between October 2005 and March 2006, and again between August and October 2006.
机译：在过去的50年中，里斯本地区发生的滑坡几乎总是由降雨引起的，并已被用来确定区域滑坡活动的降雨阈值。 2006年，研究区域发生了三起新的降雨触发的滑坡事件，分别是3月20日，10月25日至27日和11月28日。 2006年3月和2006年10月发生的滑坡事件包括平移的滑坡和很少的泥石流，相应的绝对前雨量超过了4至10天的阈值。这些事件也符合日降水量和5天校准的前期降雨值的总和。同样，与3月和10月发生的滑坡相比，2006年11月下旬发生的滑坡事件包括一些具有更深滑动面的斜坡运动。此外，还发现相应的绝对前期降雨高于40天周期降雨阈值。在这里，我们详细描述了短期和长期的大气环流条件，这些条件是引发相应滑坡事件的强降雨发作的原因。结果表明，这三个降雨事件对应着相当不同的天气大气模式，三月事件与强烈的低压系统有关，而十月和十一月事件似乎与更典型的大西洋低压系统有关（并且相关）。前线）向东行驶。最后，我们分析了北大西洋涛动（NAO）在那些以滑坡活动为特征的月份中所扮演的角色。结果表明，在滑坡事件发生之前的几个月（即2005年10月至2006年3月之间以及2006年8月至2006年10月之间），NAO指数一直为负（通常与高于平均降水量有关）。

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