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Título:
Volcano morphology and eruptive hazard of the Virunga Volcanic Province: Combining colonial-time reports, satellite images and new field observations in a conflict zone
Autor/es:
POPPE, S.; SMETS, B.; ALBINO, F.; GROSSE, P.; D'OREYE, N.; KERVYN, F.; KERVYN, M.
Lugar:
Yogyakarta
Reunión:
Congreso; Cities on Volcanoes 8; 2014
Resumen:
Within the Western branch of the East-African Rift Valley lies the
Virunga Volcanic Province (VVP), shared by DRCongo, Rwanda and
Uganda. A spatio-temporal assessment of the volcanic hazards
presented by the eight central volcanoes is essential in this region
characterized by recurrent military conflicts and a high population
density of ~one million people in the cities of Goma and Gisenyi. We
have created a volcano-structural map for the VVP using colonial-time
reports and maps, recent satellite images (SPOT, Pléiades) and a
newly-created 5 m resolution digital elevation model (TanDEM-X),
completed with limited field observations. Mapped eruptive
vents-and-fissures served as input to an eruptive vent density map
using QVAST (Bartolini et al., Nat. Haz. Earth Syst. Sci. 2013). This
map was then combined with the fragments of eruptive history of the
Virunga volcanoes, described in colonial-time reports and scientific
literature, and new 14C-ages of palaeosols above or below volcanic
cone deposits. Contrasts in erosive grade and relative age were estimated for the central volcanoes and their parasite cones through a
set of morphometric parameters calculated from the DEM. Although
the reconstructed eruptive history for the whole VVP remains
incomplete, we propose a spatio-temporal assessment of future
eruptive susceptibility. Volcanic features are generally concentrated
along major topographic lineaments, potentially controlled by palaeoand
neo-tectonic structures. Combining the morphometric data, the
available ages and the volcanic susceptibility map, the eruptive hazard
appears low to non-existent for the eastern-most volcanoes, and
medium on the long term for the central volcanoes, with a focus on
Karisimbi volcano. A 1957 lava flow, at ?Mugogo? ~10 km north of
Visoke volcano, is reportedly the only historic activity outside the rift
valley. Finally, the western-most Nyiragongo and Nyamulagira
volcanoes show abundant historic effusive activity, especially for the
latter providing sufficient temporal constraints for quantitative
eruptive susceptibility estimations.