Regional Hazard Assessment of Earthquake-Triggered Slope Instabilities Considering Site Effects and Seismic Scenarios in Lorca Basin (Spain)

Abstract

We present a regional hazard assessment of earthquake-triggered slope instabilities based on specific seismic scenarios and taking into account soil and topographic amplification effects. We followed Newmark's sliding rigid-block methodology implemented in a geographic information system (GIS) with the aim of producing regional maps in terms of critical acceleration and Newmark displacements for selected seismic scenarios. Strong ground-motion amplification site effects have been considered, particularly the topographic factor, by means of designing a GIS tool based on terrain geometry features and Eurocode-8 provisions. Three different concepts of seismic scenarios are considered in this work: probabilistic, pseudo-probabilistic, and deterministic. The study area is the Lorca Basin, located in the Eastern Betic Cordillera, one of the most seismically active regions of southeast Spain. The obtained Newmark displacement maps are compared to the distribution of known slope instabilities in the area. Future seismically induced slope instabilities in the Lorca Basin appear to be limited to isolated rock slides and rockfalls. Only the deterministic scenario (Mw >6.7) seems capable of producing widespread slope instabilities, mainly rock slides, rockfalls, and landslides.