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Age distribution of fossil landslides in the Tyrol (Austria) and its surrounding areas

机译：蒂罗尔州（奥地利）及其周围地区化石滑坡的年龄分布

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Some of the largest mass movements in the Alps cluster spatially in the Tyrol (Austria). Fault-related valley deepening and coalescence of brittle discontinuities structurally controlled the progressive failure and the kinematics of several slopes. To evaluate the spatial and temporal landslide distribution, a first comprehensive compilation of dated mass movements in the Eastern Alps has been made. At present, more than 480 different landslides in the Tyrol and its surrounding areas, including some 120 fossil events, are recorded in a GIS-linked geodatabase. These compiled data show a rather continuous temporal distribution of landslide activities, with (i) some peaks of activity in the early Holocene at about 10 500-9400 cal BP and (ii) in the Tyrol a significant increase of deep-seated rockslides in the Subboreal at about 4200-3000 cal BP. The majority of Holocene mass movements were not directly triggered by deglaciation processes, but clearly took a preparation of some 1000 years, after ice withdrawal, until slopes collapsed. In view of this, several processes that may promote rock strength degradation are discussed. After the Late-Glacial, slope stabilities were affected by stress redistribution and by subcritical crack growth. Fracture propagating processes may have been favoured by glacial loading and unloading, by earthquakes and by pore pressure fluctuations. Repeated dynamic loading, even if at subcritical energy levels, initiates brittle fracture propagation and thus substantially promotes slope instabilities. Compiled age dating shows that several landslides in the Tyrol coincide temporally with the progradation of some larger debris flows in the nearby main valleys and, partially, with glacier advances in the Austrian Central Alps, indicating climatic phases of increased water supply. This gives evidence of elevated pore pressures within the intensely fractured rock masses. As a result, deep-seated gravitational slope deformations are induced by complex and polyphase interactions of lithological and structural parameters, morphological changes, subcritical fracture propagation, variable seismic activity and climatically controlled groundwater flows.
机译：阿尔卑斯山一些最大的群众运动在空间上聚集在蒂罗尔州（奥地利）。与断层有关的山谷加深和脆性间断的聚结在结构上控制了渐进破坏和几个斜坡的运动学。为了评估时空滑坡的分布，已经对东阿尔卑斯山的过时群众运动进行了首次综合汇编。目前，在与GIS链接的地理数据库中记录了蒂罗尔及其周边地区的480多个不同的滑坡，包括约120个化石事件。这些汇总的数据显示滑坡活动的时间分布是相当连续的，（i）全新世早期的一些活动峰值在大约10 500-9400 cal BP，并且（ii）蒂罗尔州深层的岩质滑坡明显增加。在约4200-3000 cal BP处的子基体。大部分全新世质量运动不是由冰消过程直接触发的，但是显然在撤冰后直到斜坡塌陷之前，已经进行了大约1000年的准备。有鉴于此，讨论了可能促进岩石强度降低的几种方法。晚冰期后，边坡稳定性受应力重新分布和亚临界裂纹扩展的影响。冰川的装卸，地震和孔隙压力的波动可能有利于裂缝的传播过程。即使在亚临界能级下，反复的动态载荷也会引起脆性裂缝的扩展，从而大大加剧了边坡的不稳定性。汇编的年龄测年表明，蒂罗尔州的几处滑坡在时间上与附近主要山谷中一些较大的泥石流的扩散相吻合，并且在奥地利中部阿尔卑斯山还出现了冰川发展，这表明水供应增加的气候阶段。这提供了在强烈破裂的岩体中孔隙压力升高的证据。结果，岩性和结构参数，形态变化，亚临界裂缝扩展，可变地震活动和受气候控制的地下水流的复杂多相相互作用引起深层次的重力斜坡变形。

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