Tsunami Hazard Evaluation for the Head of the Gulf of Elat–Aqaba, Northeastern Red Sea

Amos Salamon,Eran Frucht,Rachamim Shem-Tov,Steven N Ward,Erez Gal,Hanan Ginat,Marina Grigorovitch,Ran Calvo

doi:10.3389/feart.2020.602462

Abstract

Unique geological and seismotectonic settings may trigger a multicascading hazard and should be identified beforehand. Such is the head of the Gulf of Elat–Aqaba (HGEA) at the northeastern end of the Red Sea where its geology, tectonics, bathymetry, and earthquake and tsunami history exhibit clear potential for earthquake and submarine-landslide tsunami generation. We thus investigated the possible tsunamigenic sources in the gulf and evaluated the resulting hazard at the HGEA. First, we assembled a bathymetric grid and adopted GeoClaw software to simulate most of the earthquake-tsunami scenarios. Next, we resolved the scheme of the largest possible tsunamigenic earthquakes along the deep basins of the Gulf of Elat (GEA) and the associated Dead Sea rift valley, as well as the potential tsunamigenic submarine landslides in the HGEA. The use of GeoClaw was verified against the 1995 tsunami generated by the Nuweiba Mw 7.2 earthquake, and then operated to simulate a suite of earthquake scenarios. Results showed that the marginal faults of Elat Basin pose the highest tsunami hazard to the Israeli part of the HGEA. To better assess that hazard, we screened the geology and seismotectonics of the HGEA and found that the Elat normal fault presents the worst-case scenario for Elat city. It is capable of generating a multicascading threat of earthquake and submarine-landslide tsunami, local subsidence that can increase inundation, and above all, destructive ground motion. Scenarios of a tsunami caused by the worst-case earthquake on the Elat fault simulated by GeoClaw and Ward’s (Tsunami, The encyclopedia of solid earth geophysics. 2011, 1473–1493) approach, and submarine landslide in the HGEA simulated by Wang et al.’s (Geophys. J. Int., 2015, 201, 1534–1544) ‘Tsunami Squares’ approach, demonstrated waves as high as 4 m along these coasts. Accordingly, we constructed a map of the evacuation zone. We also show that strong ground-shaking and retreat of the sea at the HGEA should be considered a tsunami warning, although false alarms are inevitable. Furthermore, tsunami hazard exists all along the gulf and further assessments are needed to quantify this hazard and increase awareness among the area's population.

Highlights

Some recent catastrophic tsunamis have occurred in unexpected settings that were misinterpreted or overlooked by existing early warning procedures and surprised the population
The Modeled Submarine Landslide To simplify the landslide-tsunami simulation and overcome the many unknowns in the geometrical, mechanical and hydrodynamic properties of submarine landslides that dominate the magnitude of the resulting tsunami (e.g., Ward, 2001; Løvholt et al, 2015), we focused on the largest recognizable slump in the head of the GEA (HGEA) as representing the worst case of landslidetsunamis (Table 2, case ‘b’)
Seismotectonic considerations: As we were interested in the return period of the faults that pose the highest tsunami hazard to the HGEA, either directly by earthquake or by submarine failure, we focused on the marginal faults of the Elat Basin and the main transform

Summary

Introduction

Some recent catastrophic tsunamis have occurred in unexpected settings that were misinterpreted or overlooked by existing early warning procedures and surprised the population Such were, for example, the sudden 1998 Papua New Guinea tsunami that followed a nearby seismogenic submarine landslide (Synolakis et al, 2002), the multiple cascading earthquake and tsunami hazards triggered by the 2018 Sulawesi strike-slip earthquake that severely affected Palu Bay (Goda et al, 2019), and the tsunamigenic collapse of the Anak Krakatoa emerging volcano (Walter et al, 2019). The head of the GEA (HGEA), which is occupied by Egypt, Israel, Jordan and Saudi Arabia, is undergoing intensive development of residential districts, infrastructure facilities, and international tourist resorts with inner lagoons and large hotels Realizing that this is a unique setting of a transform in a marine environment with the potential of generating both earthquake and submarine-landslide tsunamis, we initiated a tsunami hazard evaluation for the HGEA to characterize the hazard and assess its potential severity

Methods

Findings

Discussion

Conclusion