Applicability of Newmark method at regional, sub-regional and site scales: seismically induced Bullas and La Paca rock-slide cases (Murcia, SE Spain)

Abstract

In this paper, the applicability of the Newmark method at regional, sub-regional and site scales has been investigated in the Lorca Basin (Murcia). This basin is located in one of the most seismically active regions of Spain. The area is very interesting for studying earthquake-induced slope instabilities as there are well-known cases associated with specific earthquakes. For the regional and sub-regional scales, a geographic information system has been used to develop an implementation of Newmark sliding rigid block method. Soil and topographic amplification effects have been particularly considered. Subsequently, ‘Newmark displacement’ maps for deterministic seismic scenarios have been produced. Some specific studies have also been performed using limit equilibrium methods to estimate the safety factor and the critical acceleration of certain slope instabilities at a site scale. These instabilities were the rock slides related to recent seismic series at the Lorca Basin: 2002 Bullas (Mw = 5.0) and 2005 La Paca (Mw = 4.8). Finally, the safety factor, critical acceleration and Newmark displacement values estimated at different scales have been compared to determine which scale is most suitable for the Newmark method.