Assessment of seismic risk in the upper Tinee valley, southeastern France
Résumé
Seismic risk scenario has already been established for major urban centre by the past, but it is of importance to assess also the seismic risk in wide areas with sparse dwelling centres and few connecting roads. The concept developed consists in linking, for each element at risk, vulnerability values together with hazard values, in order to produce for a given scenario, risk values relative to road failure or building damage. We had to overpass two antagonistic specifications of wide area scenario : the scale of survey should be large enough to be economic and simple, but a very small element can be responsible for road failure or building collapse. Hazard is expressed in terms of maximum horizontal acceleration of soil, starting point of the risk analysis. Induced phenomena (liquefaction, landslide and rock fall) occurrence are evaluated from basic soil classifications and expressed in terms of minimum PGA value that can trigger it. For each of these hazard and for each element at risk, a simple vulnerability value is evaluated. A standard geographical information system allows gathering these data in order to produce maps pointing out road failure and building damage distribution. The paper presents the important features of a comprehensive study, highlights the methodology discusses the results and provides insights to the future developments.