V23A-3080
Lava Flow Hazard Assessment at Fogo Volcano, Cape Verde on the Base of Combined Terrestrial Laser Scanner and Photogrammetric Data

Tuesday, 15 December 2015
Poster Hall (Moscone South)
Nicole Richter1, Massimiliano Favalli2, Elske De Zeeuw van Dalfsen1, Alessandro Fornaciai2, Rui Manuel Silva Fernandes3, Nemesio Miguel Perez4, Judith Levy1, Sonia Silva Victoria5 and Thomas R Walter1, (1)Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Potsdam, Germany, (2)National Institute of Geophysics and Volcanology - Pisa section, Pisa, Italy, (3)University of Beira Interior, Covilha, Portugal, (4)Canary Islands Volcanology Institute INVOLCAN, Puerto de la Cruz, Tenerife, Spain, (5)University of Cape Verde, Praia, Santiago, Cape Verde
Abstract:
On November 23, 2014, after almost 20 years of dormancy, a major Hawaiian- to Strombolian-type eruption started at Fogo Volcano, Cape Verde. The eruption was very similar in style to previous eruptions and occurred from a vent at the western flank of the Pico do Fogo stratocone (2829 m). During this eruption, about 200 residential buildings and a significant portion of agricultural land were destroyed by lava flows. Also, the only road was blocked by lava, impeding evacuation and emergency response. As future eruptions could follow a similar pattern, and reconstruction of buildings and infrastructure has commenced, a detailed analysis of the pre- and post-eruptive topography, as well as a comprehensive lava flow hazard and risk assessment are needed.

During a field campaign in January 2015, we collected Terrestrial Laser Scanner (TLS) and photogrammetric data. We construct a Digital Elevation Model (DEM) from almost 165 million TLS data points, covering 87.7 % of the new lava flows and most of the Chã das Caldeiras. We use the photogrammetric data and the Structure from Motion (SfM) method to cover the remaining 12.3 % of the affected area. By combining the TLS and SfM datasets, we construct an updated and high-quality DEM, including details on the lava flow morphology and the 2014/2015 eruptive vent. We estimate the total erupted lava volume and area by subtracting a pre-eruptive from the post-eruptive DEM.

Based on this dataset, we are able to assess the lava flow hazard by simulating possible lava flow paths using the DOWNFLOW probabilistic code. We use a pre-eruptive DEM to reconstruct the flow paths of the 2014/2015 eruption. The new post-eruptive DEM is used to forecast possible future lava flow paths. We combine the hazard map with information on existing infrastructure (i.e. roads and settlements) in order to estimate the lava flow risk. As a final result we provide up-to-date lava flow hazard and risk maps for Fogo Volcano, Cape Verde.

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