Réf. Corsini & al 2000 - A

Référence bibliographique complète
CORSINI A., PASUTO A., SOLDATI M. Landslides and climate change in the Alps since the Late-glacial: evidence of case studies in the Dolomites (Italy). In: Bromhead, E., Nixon, N., Ibsen, M.-L. (Eds.), Landslides in Research, Theory and Practice. Thomas Telford Publishing, London, 2000, p. 329–334.

Mots-clés
 

Organismes / Contacts
Department of Earth Sciences, University of Modena and Reggio Emilia, Modena, Italy. C.N.R.-I.R.P .1., Research Institute for Hydrological and Geological Hazard Prevention, Padova, ltaly. Department of Earth Sciences, University of Modena and Reggio Emilia, Modena, ltaly.

(1) - Paramètre(s) atmosphérique(s) modifié(s)
(2) - Elément(s) du milieu impacté(s)
(3) - Type(s) d'aléa impacté(s)
(3) - Sous-type(s) d'aléa
       

Pays / Zone
Massif / Secteur
Site(s) d'étude
Exposition
Etage / Tranche d'altitude
Période(s) d'observation
Italy Dolomites Cortina d'Ampezzo and Alta Badia     Holocene

(1) - Modifications des paramètres atmosphériques
Reconstitutions
On a large time-scale, the dates gathered in the area of Cortina d'Ampezzo and in Alta Badia show clusters of landslide events in two periods characterised by marked climatic changes: the early Post-glacial and the Subboreal. In the early Post-glacial (Preboreal and Boreal), after the retreat of the Würmian glaciers, increased precipitation is reported.
Observations
 
Modélisations
 
Hypothèses
 

Informations complémentaires (données utilisées, méthode, scénarios, etc.)
Palaeoclimate curves are [from] Orombelli and Ravazzi (1996) and Goudie (1992); chrono-zones boundaries are after Orombelli and Ravazzi (1996).

(2) - Effets du changement climatique sur le milieu naturel
Reconstitutions

 

Observations
 
Modélisations
 
Hypothèses
 

Sensibilité du milieu à des paramètres climatiques
Informations complémentaires (données utilisées, méthode, scénarios, etc.)

 

(3) - Effets du changement climatique sur l'aléa
Reconstitutions

The oldest dates obtained, ranging between 13,000 and 10,000 cal. yr BP, refer, on the one band to huge rock slides, now inactive, which affected dolomitic rocks after the retreat of the Würmian glaciers and, on the other hand, to slides and earth flows mainly involving pelitic rocks. The rock slides (Col Drusciè Zuel, Pierosà), which occurred when slopes were no longer sustained by ice masses markedly modified the morphology of the Cortina valley with their hill-shaped accumulations which, later on, have been partly remobilised by successive slides and flows. An example of this is given by the Pierosà rock slide body which was partly reactivated by a series of earth flows (Cortina landslide) since 10,000 cal. yr BP. Early Holocene dates have been collected also for other earth flows, such as that of Lacedel, probably triggered in the Late-glacial. The Lacedel landslide had a recurrent activity during the Holocene and also at present shows a high rate of movement. For other earth flows (La Riva, Pezzié, Chiamulera, Chiave) early Holocene movements are not documented, but a series of dates which show a cluster of events between 5500 and 2500 cal. yr BP have been achieved. However, it was not possible to define whether the dated events were first time failures or reactivations of older movements.

In Alta Badia, [...] the oldest events dated range from about 10,000 to 9000 cal. yr BP and refer to massive earth flows subsequent to large-scale rotational slides, which affected the bedrock clown to 40-50m in depth. More recent movements, mainly spanning from about 5000 to 2000 cal. yr BP, refer to earth flows which episodically moved along more shallow shear surfaces. Apart from a reactivation of the Arlara landslide, dated to ca. 7700 cal. yr BP, other landslides in Alta Badia fit in a similar time span. In fact, in the northem part of the Badia valley landslide events have been dated at about 5600 cal. yr BP (San Leonardo earth flow) and about 5000 cal. yr BP (Colfosco rock fall). More recent dates (2800 to 2500 cal. yr BP) refer to two superimposed earth flows, separated by a 20cm thick soil, which detached from the accumulation of a much larger rotational slide near San Cassiano. The research in Alta Badia bas also identified the recurrent formation, in the past, of a dam-lake downstream of Corvara in Badia. Valley damming bas been related to the Col Maladat rotational slide. Charcoals from cores of the dam-lake deposits, together with sedimentary evidence, date damming conditions in two distinct periods: from about 10,000 to 7000 cal. yr BP and from about 4000 to 1000 cal. yr BP. It is likely that the onset of the oldest damming event closely post-dates an early sliding event. On the other hand, the most recent lacustrine phase, which appears to have taken place after the oldest lake was extinguished, should be related to a partial reactivation of the landslide due to debris slides and flows.

On a large time-scale, the dates gathered so far in the area of Cortina d'Ampezzo and in Alta Badia show clusters of landslide events in two periods characterised by marked climatic changes: the early Post-glacial (Preboreal and Boreal) and the Subboreal. The causes and types of mass movements of these two clusters are, however, substantially different.

The first cluster includes landslides of various types which occurred in the early Post-glacial when, after the retreat of the Würmian glaciers, slopes became prone to mass movements. On the one hand, these movements consist of rock slides of considerable size (e.g. Zuel and Col Drusciè landslides) detached from the steep dolomitic rock walls no longer sustained by ice masses, as a consequence of glaciopressure implications (cf. Panizza. 1973); on the other hand, they consist of complex movements (Corvara), rotational slides (Col Maladat) and earth flows (Lacedel, Cortina, La Riva) which affected the pelitic formations outcropping in the middle and lower part of the slopes, as a consequence of higher availability of groundwater; the latter is likely to be connected to increased precipitation and permafrost melting (cf. Soldati, 1999). In a European perspective, the period during which these landslides took place coïncides with the oldest period of frequent post-glacial slope movements identified in Europe by various authors (e.g. Starkel, 1966; González Díez et al., 1996; Berrisford and Matthews, 1997; Lateltin et al., 1997; Margielewski, 1998).

The second cluster of landslides, which coïncides with the Subboreal period, includes, in both study areas, mostly earth flows involving pelitic rocks. The dated movements are likely to be reactivations of older landslides rather than first time failures, since the same slopes appear to have been mobilised more than once in the past. The period of occurrence corresponds with an increase of precipitation reported in literature. However, the hypothesis of a direct influence of this climate change on landslides, partially confirmed by other European case smilles (e.g. González Díez et al., 1996; Berrisford and Matthews, 1997; Lateltin et al., 1997), still needs further verification especially through the comparison with other alpine sites.

However, the Cortina d'Ampezzo and Alta Badia areas have been affected by landslides also during other periods of the Holocene: the recurrent activity bas been favoured by non-climatic factors such as seismic events and litho-structural characteristics of the rock types involved which are either affected by dense networks of joints (dolomites) or markedly ductile (pelitic rocks). Also extreme meteorological events, not specifically related to climate changes, may have triggered mass movements.

Observations
 
Modélisations
 
Hypothèses
 

Paramètres de l'aléa
Sensibilité du paramètre de l'aléa à des paramètres climatiques et du milieu / Facteurs de contrôle
Informations complémentaires (données utilisées, méthode, scénarios, etc.)
Mass movement occurrence Precipitation

As regards the area of Cortina d'Ampezzo, more than thirty landslides of different type, size age and degree of activity have been identified (Panizza, 1990; Panizza et al., 1996; Pasuto et al., 1997), several of which have been dated by means of radiocarbon method.

In Alta Badia a series of radiocarbon dates of landslides and related lacustrine deposits have been collected (Corsini et al., 1999). Many of the dates available refer to movements of the Corvara landslide, a complex phenomenon (slide-flow) located just south of Corvara in Badia. [...]

- Calibrated data from Radiocarbon Calib. Program 4.1 (by Stuiver and Reimer, 1993; Dataset: Stuiver rt al., 1998);
-
Cal. method: Intercept.

Palaeoclimate curves are [from] Orombelli and Ravazzi (1996) and Goudie (1992); chrono-zones boundaries are after Orombelli and Ravazzi (1996).


(4) - Remarques générales

 


(5) - Syntèses et préconisations

 

Références citées :

Berrisford M.S. and Matthews J.A., 1997. Phases of enhanced rapid mass movement and climatic variation during the Holocene: a synthesis. Palaoklimaforschung–Palaeoclimate Research, 19, 409-440.

Corsini A., Pasuto A. and Soldati M., 1999. Geomorphological investigation and management of the Corvara landslide (Dolomites, Italy). JGU Transactions, 20(3), 169-186.

González Díez A., Salas L., Díaz de Terán J.R. and Cendrero A:, 1996. Late Quaternary climate changes and mass movement frequency and magnitude in the Cantabrian region,  Spain. Geomorphology, 15,291-309.

Goudie A., 1992. Environmental change. Third Edition, Oxford Univ. Press, Oxford, 329  pp.

Lateltin O., Beer C., Raetzo H. and Caron C., 1997. Landslides in Flysch terranes of Switzerland: Causal factors and climate change. Eclogae geol. Helv., 90, 401-406. [Fiche Biblio]

Margielewski W., 1998. Landslide phases in the Polish outer Carpathians and their relation to climatic changes in the Late Glacial and the Holocene. Quat. Studies in Poland, 15, 37-53.

Orombelli G. and Ravazzi C., 1996. The Late Glacial and Early Holocene chronology and paleoclimate. Il Quatemario, 9(2), 439-444.

Panizza M., 1973. Glacio Pressure Implications in the Production of Landslides in the Dolomitic Area. Geol. Appl. e Idrogeol., 8(1), 289-297.

Soldati M., 1999. Landslide Hazard Investigations in the Dolomites (ltaly): The Case Study of Cortina d'Ampezzo. In: R. Casale and C. Margottini (eds.), Floods and Landslides: Integrated Risk Assessment. Springer-Verlag, Berlin, 281-294.

Starkel L., 1966. Post-glacial climate and the moulding of European relief. Proc. Int. Symp on World Climate from 8000 to 0 B.C., Royal Meteorological Society, London, 15-33.