Simulation of fault planes and seismic hazard distribution maps using GIS-based 3D modeling algorithms for a seismic risk mitigation study in Egypt

Abstract

Although Egypt is generally considered an area of low to medium seismicity, it has experienced recurring destructive earthquakes throughout its history. The distribution of damage is significantly influenced by fault geometry and local site effects. Consequently, assessing seismic hazards has become a major challenge in effectively mitigating seismic risk. This study aims to develop a geographic information system (GIS)-based three-dimensional (3D) modeling framework to enhance seismic hazard assessments in Egypt, a region of low to medium seismicity that has historically faced destructive earthquakes. The research focuses on integrating fault-specific parameters, geological data, and local site effects into deterministic seismic hazard models. Using 3D fault modeling algorithms, fault plane geometries are generated based on fault traces, geological features, and topography. To account for local site effects, a 3D grid-mesh system models ground motion velocity amplification, incorporating average shear-wave velocity and a soil susceptibility map. The developed methodology is then applied to simulate seismic hazard maps for the October 12, 1992, Dahshour earthquake; the October 11, 1999, Beni Suef earthquake; and a scenario analysis for a maximum expected magnitude 6.5 Dahshour earthquake. Validation of the 1992 Dahshour earthquake simulation against observed isoseismal maps and damage evidence demonstrates the model’s reliability in reproducing high-intensity zones (MMI = VII–VIII). The scenario-based analysis highlights high-risk areas vulnerable to liquefaction and significant ground motion amplification, underscoring the critical need for updated building codes and disaster mitigation strategies. Despite data limitations, the GIS-based 3D modeling framework serves as a robust tool for detailed seismic hazard assessments, helping local governments and planners identify high-risk zones, prioritize mitigation efforts, and enhance disaster preparedness in Egypt and similar regions.