Forecasting database for the Tsunami Warning Center for the western Mediterranean Sea

Abstract

A first generation model-based tsunami prediction system is being developed as part of the French Tsunami Warning Center that will be operational by mid 2012. It involves a pre-computed unit source functions database (i.e., a number of tsunami model runs that are calculated ahead of time and stored) corresponding to tsunami scenarios generated by a source of seismic moment 1.75E+19 N.m. In addition, an authomatized composite scenarios calculation tool is implemented to allow the simulation of any tsunami propagation scenario (i.e., of any seismic moment). The strategy is based on linear combinations and scaling of a finite number of pre-computed unit source functions. This tool produces maps with uncertainties (in epicenter location and magnitude) of expected maximum wave amplitude in deep ocean at each grid node rapidly. A no-dimension code representation is chosen to show zones in the main axis of energy at the basin scale. An example on the 2003 Boumerdès earthquake (Mw=6.9, northeastern Algerian margin) is presented. This forecast system provides warning refinement compared to the rough tsunami risk map given by the decision matrix.