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MEGAHazards, “Mass-wasting Episodes in the Geological Evolution of the Azores islands: timing, recurrence, mechanisms and consequences”, is a research project funded by Fundação para a Ciência e a Tecnologia (FCT) Portugal (PTDC/CTE-GIX/108149/2008).

Volcanic ocean islands are among the highest and most unstable topographic relieves on Earth. Their sub-aerial evolution occurs over short spans of time, as a consequence of volcanic construction, and destruction by mass-wasting processes including giant sector-collapses, shallow landslides and protracted long-term erosion. Giant sector collapses such as recognized around numerous volcanic islands represent a major threat, since they can generate fast running debris avalanches and trigger large tsunamis.

On the other hand, shallow landslides are a frequent expression of the dynamic nature of denudation. They contribute to the rapid evolution of the landscape, and produce significant amounts of debris, which may cause serious damage. The Azores in the Atlantic Ocean are particularly exposed to mass-wasting hazards, in an area of intense regional deformation characterized by recurrent high-magnitude earthquakes.

The islands have been mainly edified during the late Quaternary and are subjected to a very humid climate. Their geology is marked by a multi-stage evolution including fast-growing phases and multiple destruction events in the form of vertical caldera collapse, lateral landslides and rock fall of various sizes.

This project aims at reconstructing the morpho-structural evolution of selected islands from the Azores, with a particular emphasis on the analysis of past and present mass-wasting processes. We wish to characterize the distribution, the magnitude, the timing and recurrence, the mechanisms and the consequences of landslides over the lifetime of the islands.

The study will target on the eruptive systems of Pico, Faial, S. Miguel, S. Jorge, Terceira and Flores, which concentrate most of the population and infrastructures and are the locus of intense tourism. The methodology proposed includes fieldwork and geological sampling on the islands (task 1), high-precision geochronology (K/Ar, Ar/Ar) on target volcanic samples (task 2), palaeomagnetic analyses on slid/tilted blocks (task 3), whole-rock geochemistry (task 4), the production of high-resolution bathymetric and topographic maps around and in the islands (task 5), geophysical soundings for the characterization of the deep structure of active major mass-wasting events (task 6), quantitative geomorphological reconstructions (task 7), numeric simulations of debris propagation and tsunami generation (task 8), and the production of a webpage including reports for dissemination of the results to a large audience (task 9).

The research team includes experts on the several areas of knowledge and methods necessary for this project. The multi-disciplinary study proposed in the present project will provide valuable insight on the different factors favouring the development of slope instabilities, the mechanisms of the rupture, the processes controlling the mobility and the dynamics of landslides, and their geological and societal impacts. It will have significant implications for risk assessment and hazard planning in the Azores.

 

June 2010
1st Fieldwork Campaign
FO Marques, A Hildenbrand, P Silva, JC Nunes and B Henry participated [+]

November 2010
2nd Fieldwork Campaign
FO Marques and the new PhD student Ana Cristina Costa participated. Ana was born in Pico, so she knows the terrain! [+]

 

1st Fieldwork Campaign [+]

 

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