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

Evidence of paleotsunami deposit in recent sediments of Algiers (Kaddous area)

M. LARARA (1), A. NEDJARI (1), M. MEGHRAOUI (2)
(1) Science and technology university Houari Boumediene, Geodynamic of sedimentary Basins and Orogenies Laboratory, Departement of geology, Algiers, Algeria
(2)EOST-IPGS-UMR 7716, Strasbourg, France, malikalarara@yahoo.fr

In order to recognize records of paleotsunamis in recent formations of El Kaddous area (Eastern part of Algiers), we performed short cores (5-6 m), which have been completed by field observations in El Kaddous area. Detailed sedimentological and paleontological analysis allows us to highlight a very inserting layer. It has a sharp basal erosional contact. Its organization and composition are different from the rest. It is characterized by high percentage of fragmentation of local bivalve shells. It is also composed by an heterogeneous material: sand, gravel, clay and silt, in total desorganisation.

We performed micropaleontological analysis on samples collected from this anomalous layer. It contains marine Foraminifera (benthic and planctonic), frequent fragments of mollusks and corals. The C14 dating of this catastrophic layer ranges between AD 1680-1810. At that time, the Algiers region has experienced two major earthquakes: 03/03/1716 and 06/05/1773. This event would be contemporary with that described and dated by Maouche et al (2009), on the coasts of Algiers (from Dellys to Tipaza) and detachments that have generated and block moves.