Repeated historical earthquakes in Sousse, Monastir and El-Jem (Tunisia)\u2014an archaeoseismological study

Miklós Kázmér

doi:10.1007/s12517-020-06372-w

Abstract

Tunisia is known of sparse and moderate earthquakes. However, there are seismically damaged historical buildings in the eastern Sahel region. The Roman amphitheatre of Thysdrus (modern El-Jem), various Islamic religious and secular buildings in Sousse and Monastir testify to seismic events with intensity up to IX (EMS98 scale). We raise the hypothesis that their destruction was caused by the nearby east-west Cherichira-Abaieh Fault and the north-south Monastir Fault. Simultaneity of the 859 AD Kairouan earthquake and extensive restoration works in Sousse 50 km to the east allow assessing magnitude up to 7.2 based on segment length. The city was hit both by the 859 AD and a post-1575 earthquake. Being nearby two active faults, seismic hazard in Sousse is higher than either in Kairouan or in Monastir.

Highlights

The diffuse plate boundary along the northern margin of Africa had earthquakes up to M 7.3 during the past six decades
Tectonic activity is concentrated along transpressional folds and strike-slip faults within the coastal Atlas region, both onshore and offshore (Meghraoui and Pondrelli 2012)
Thysdrus was the rich centre of olive growing in Tunisia in Antiquity, briefly rising to the rank of imperial capital in the AD 230s

Summary

Introduction

The diffuse plate boundary along the northern margin of Africa had earthquakes up to M 7.3 during the past six decades. Tectonic activity is concentrated along transpressional folds and strike-slip faults within the coastal Atlas region, both onshore and offshore (Meghraoui and Pondrelli 2012). The Tunisian sector is the best studied (Bahrouni et al 2020b), having sparse and moderate seismic events up to M 4.7 since 1981, dominated by strike-slip faults (Bahrouni et al 2014). Historical seismology, from Ambraseys (1962) to Kharrat et al (2019), revealed that earthquakes larger than M 7 are possible (Fig. 1). The author carried out pilot studies in three sites in the less seismic eastern Sahel region of Tunisia: Roman Thysdrus (modern El-Jem) and in the Islamic medina (old town) of Sousse and Monastir (Fig. 1) (Kázmér 2019). Earthquake archaeological effects are illustrated below, discussed in the framework of active tectonics

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Conclusions

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