Volcano instabilities and debris avalanche hazard in the East African Rift
| dc.contributor.author | Delcamp, A. | |
| dc.contributor.author | Macheyeki, A. | |
| dc.contributor.author | Kwelwa, S. | |
| dc.contributor.author | Delvaux, D. | |
| dc.contributor.author | Poppe, S. | |
| dc.contributor.author | Kervyn, M. | |
| dc.date | 2013 | |
| dc.date.accessioned | 2016-03-15T10:05:56Z | |
| dc.date.available | 2016-03-15T10:05:56Z | |
| dc.identifier.uri | https://orfeo.belnet.be/handle/internal/1968 | |
| dc.description | Volcanoes tend to develop gravitational instabilities during their lifetime, essentially due the presence of hydrothermal layers or superficial aquifer, dyke injection and the nature of the basement. Once the volcano reached an unstable state, earthquake, strong wind, new dyke injection or eruption can trigger flank collapse, resulting into a debris avalanche which is characterised by high mobility and long run-out and poses thus a serious threat for nearby population. Many volcanoes that are scattered along the East African Rift System (EARS) present sign of past instabilities, such as remnant scar of a sector collapse or debris avalanche deposit, as well as sign of long term deformation, such as spreading. We focused our study on the North Tanzanian Divergence Zone (NTDZ), where the eastern branch of the EARS splits into several branches, at the border between Kenya and Tanzania. Using remote sensing analyses based on 90m DEM (landsat-SRTM-ETM+), we highlighted several debris avalanche deposits (DADs) some of them being to our knowledge- unknown or at least not mentioned in previous literature. Among the edifices, we noticed Mt Meru a 4566m high strato-volcano, which presents three debris avalanche deposits, with the major and last one running up to the feet of Kilimanjaro volcano with an estimated collapsed volume of at least 14km3 and covering an area of 1250km2 (Fig.1). From field investigation, we realised that the two older avalanches are linked to plinian eruption while the last collapse event is tectonic related. Considering the quite large amount of debris avalanche deposits in the NTDZ, we then explore the regional tectonic trends to highlight a potential link that would explain collapse recurrence. Even though the volcanoes from Virunga province are mainly effusive, past explosive activity is not to exclude. Their position in an active tectonic region make them potential candidates for future destabilisation event, such as the steep and high mount Karisimbi. Old volcanoes, such as Mikeno and Sabinyo show also structures that might be linked to volcano long term deformation or instabilities and a major scar on the Mikeno is probably the remnant of a past catastrophic collapse even though deposits are not found yet. | |
| dc.language | eng | |
| dc.title | Volcano instabilities and debris avalanche hazard in the East African Rift | |
| dc.type | Conference | |
| dc.subject.frascati | Earth and related Environmental sciences | |
| dc.audience | Scientific | |
| dc.subject.free | Geodynamics and mineral resources | |
| dc.source.title | AVCOR Meeting on Active Volcanism and Continental Rifting, Gisenyi, 12-14 Nov. 2013 | |
| dc.relation.project | Geo-Risk in Central Africa: integrating multi-hazards and vulnerability to support risk management ( Federal ) | |
| Orfeo.peerreviewed | No | |
| dc.identifier.rmca | 3710 |
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