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| Titel |
Age distribution of fossil landslides in the Tyrol (Austria) and its surrounding areas |
| VerfasserIn |
C. Prager, C. Zangerl, G. Patzelt  , R. Brandner |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 8, no. 2 ; Nr. 8, no. 2 (2008-04-24), S.377-407 |
| Datensatznummer |
250005417
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| Publikation (Nr.) |
 copernicus.org/nhess-8-377-2008.pdf |
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| Zusammenfassung |
| 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. |
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