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| Titel |
Rainfall-triggered landslides in the Lisbon region over 2006 and relationships with the North Atlantic Oscillation |
| VerfasserIn |
J. L. Zêzere, R. M. Trigo, M. Fragoso, S. C. Oliveira, R. A. C. Garcia |
| 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. 3 ; Nr. 8, no. 3 (2008-05-15), S.483-499 |
| Datensatznummer |
250005527
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| Publikation (Nr.) |
 copernicus.org/nhess-8-483-2008.pdf |
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| Zusammenfassung |
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. |
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