Seismic Hazard Analysis of Surface Level, Using Topographic Condition in the Northeast of Algeria

Abstract

The aim of this study is to conduct a probabilistic seismic hazard analysis and spatial variation of seismic hazard at the surface level for Northeast of Algeria, covering 4°E–9°E, 33°N–38°N. The most recent peak ground acceleration (PGA) attenuation relationship, along with the updated seismic catalog and the best knowledge on the seismic activity in the study area have been used to estimate the seismic hazard and its uncertainty. Two types of seismic source models, linear sources and areal sources, were considered to model the seismic sources. Different sets of ground motion prediction equations were used for different tectonic provinces to characterize the attenuation properties. The hazard estimation at bedrock level was carried out using a probabilistic approach and the results obtained from various methodologies were combined into a logic tree framework. In this paper, we generate PGA maps with 10% probability of exceedance in 50 years, for a rock site condition. The seismic site characterization of Algeria was done using topographic slope map derived from Digital elevation model data. We estimate the seismic hazard from the seismicity catalog and not from faults with recurrence rates obtained from geologic data. The hazard estimation at surface level, is achieved through the use of appropriate site amplification factors corresponding to various site classes based on topographic gradient. Spatial variation of surface level PGA for return periods of 100, 475 years and 2000 years are presented as contour maps. The maps obtained in this study are based on the assumption that the process of earthquake occurrence is inherently Poissonian, so that the probabilistic ground motion is time-independent.