Crustal Strain and Stress Fields in Egypt from Geodetic and Seismological Data

Mohamed Rashwan,Rashad Sawires,Federica Sparacino,Ali M Radwan,José Antonio Peláez,Mimmo Palano

doi:10.3390/rs13071398

Abstract

The comparison between crustal stress and surface strain azimuthal patterns has provided new insights into several complex tectonic settings worldwide. Here, we performed such a comparison for Egypt taking into account updated datasets of seismological and geodetic observations. In north-eastern Egypt, the stress field shows a fan-shaped azimuthal pattern with a WNW–ESE orientation on the Cairo region, which progressively rotated to NW–SE along the Gulf of Aqaba. The stress field shows a prevailing normal faulting regime, however, along the Sinai/Arabia plate boundary it coexists with a strike–slip faulting one (σ1 ≅ σ2 > σ3), while on the Gulf of Suez, it is characterized by crustal extension occurring on near-orthogonal directions (σ1 > σ2 ≅ σ3). On the Nile Delta, the maximum horizontal stress (SHmax) pattern shows scattered orientations, while on the Aswan region, it has a WNW–ESE strike with pure strike–slip features. The strain-rate field shows the largest values along the Red Sea and the Sinai/Arabia plate boundary. Crustal stretching (up to 40 nanostrain/yr) occurs on these areas with WSW–ENE and NE–SW orientations, while crustal contraction occurs on northern Nile Delta (10 nanostrain/yr) and offshore (~35 nanostrain/yr) with E–W and N–S orientations, respectively. The comparison between stress and strain orientations over the investigated area reveals that both patterns are near-parallel and driven by the same large-scale tectonic processes.

Highlights

Introduction iationsEgypt is part of the north-eastern sector of the African continent (Figure 1), where different tectonic plates interact by a complex tectonic evolution since Late Cretaceous [1].It is surrounded by three plate boundaries where convergent (Hellenic and Cyprian Arc systems), divergent (Gulf of Suez–Red Sea) and transform faulting (Gulf of Aqaba– Dead Sea fault system) processes are currently occurring [2]
We firstly provided an improved snapshot of the present-day crustal tectonic stress and strain-rate fields over Egypt by taking into account updated datasets of seismological and geodetic observations
fault plane solutions (FPSs) catalog consists of 451 solutions which mainly concentrated on the north-eastern sector of catalog

Summary

Introduction

Egypt is part of the north-eastern sector of the African continent (Figure 1), where different tectonic plates interact by a complex tectonic evolution since Late Cretaceous [1]. It is surrounded by three plate boundaries where convergent (Hellenic and Cyprian Arc systems), divergent (Gulf of Suez–Red Sea) and transform faulting (Gulf of Aqaba– Dead Sea fault system) processes are currently occurring [2]. The current tectonic context of Egypt and its surrounding regions is the result of a complex tectonic evolution started in Late Cretaceous with the beginning of the Eurasia–Africa convergent process [1]. Differential movement between the Arabian and African/Sinai plates started in Early Miocene with the branching of the northern Red Sea basin into the

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Conclusion