Comparación del método de Newmark a escala regional, local y de emplazamiento: el caso del desprendimiento de la Paca

Abstract

The Lorca Basin (Murcia) is located in one of the most seismically active regions of Spain. This area is very interesting for studying earthquake-induced slope instabilities as there are well known cases associated to specific earthquakes (e.g., 2002 Bullas, 2005 La Paca). In this work we present our investigations at regional, local and site scales. For regional and local scales, we have used a GIS to develop an implementation of Newmark’s sliding rigid block method. We have particularly introduced a new variation to consider soil and topographic amplification effects. Subsequently, we have produced «Newmark displacement» maps for deterministic seismic scenarios. We have found that rock-falls produced during the last earthquakes in Lorca Basin are associated to Newmark displacements lower than 2 cm. To support this hypothesis we have applied the Newmark method to La Paca rock-fall at a site scale. We have performed a back-analysis to estimate the static safety factor and the critical acceleration. Finally, we have compared the safety factor, the critical acceleration and the Newmark displacement calculated at La Paca rock-fall at a site scale with our GIS estimations in order to improve the calibration of Newmark’s method at the regional scale