Understanding Extreme Geohazards: The Science of the Disaster Risk Management Cycle European Science Foundation Conference November 28 to December 1, 2011, Sant Feliu de Guixols, Spain

Submarine land sliding on the continental slope off Central America and the influenced of long-term tectonic Erosion

Rieka Harders (1), César R. Ranero (2), Wilhelm Weinrebe (3)
(1)SFB 574, Leibniz‐Institut für Meereswissenschaften an der Universitat Kiel, (IFM‐GEOMAR), Wischhofstrasse 1‐3, D‐24148 Kiel, Germany, rharders@ifm‐geomar.de,
(2)Barcelona Center for Subsurface Imaging, ICREA, Instituto de Ciencias del Mar, CSIC, Pg. Marítim de la Barceloneta 37‐49, E‐08003 Barcelona, Spain, cranero@icm.csic.es,
(3)SFB 574, Leibniz‐Institut für Meereswissenschaften an der Universität Kiel, (IFM‐GEOMAR), Wischhofstrasse 1‐3, D‐24148 Kiel, Germany, wweinrebe@ifm‐geomar.de

We have studied extensive submarine land sliding using a seafloor topography and side-scan sonar data along the continental slope of the Middle America Trench. This subduction zone is dominated by tectonic erosion. Studies during the last few decades have shown that submarine mass wasting is a common and well developed process on slopes around the world’s continental margins, hot-spot volcanic islands, and volcanic island arcs. Although tectonic erosion is active in about 50% of the world subduction zones submarine mass movements at subduction zones dominated by tectonic erosion are comparatively limited. Distinct failures have been studied at slopes in Peru, Costa Rica, Nicaragua and New Zealand but extensive surveys have not been obtained. Here we present a comprehensive data set on seafloor mapping on a subduction zone dominated by tectonic erosion that covers much of the Middle America Trench (MAT) from the Mexico-Guatemala border to Costa Rica-Panama border. This contribution aims to give an overview on the level and diversity of submarine land sliding from large and catastrophic scale events, like avalanches and large slumps to frequent small-scale sliding on the continental slope. As some case studies indicated natural disasters like tsunamis generated from these events have to be taken into account. Here we evaluate how long-term tectonics caused by subduction erosion preconditions the continental slope structure to modulate the generation of land sliding. We show that changes in subduction erosion processes, interacting with the local topography of the subducting plate correlate to variations in the type and distribution of failures along the slope of the region.