Tunisia

Tunisia occupies the northeastern tip of the African continent, where the African plate converges with the Eurasian plate in the central Mediterranean. This convergence, at approximately 3 to 5 millimetres per year, generates compressional stress in northern Tunisia, expressed through fold-and-thrust structures in the Tell Atlas continuation and the northern Tunisian ridges. Tunisia is moderately seismically active by African standards, with the highest hazard concentrated in the northern part of the country.

The most seismically active zone in Tunisia is the northeast — the Cape Bon Peninsula, the Tunis area, and the offshore Pelagian Shelf. The Pelagian Sea between Tunisia and Sicily is underlain by continental crust (the Pelagian Block) and contains several active [[fault]] systems. The 1972 earthquake near El Kef in northwestern Tunisia (magnitude 5.5) and the 1999 magnitude 5.8 earthquake near Aïn Draham caused building damage and public alarm. Historical records describe significant earthquakes affecting Tunis and Carthage in antiquity.

The most damaging earthquake in Tunisia's modern history struck on 25 October 1985 near El Kef in the northwest, with a [[magnitude]] of 5.9 killing 6 people and injuring dozens. The Kef region sits near an ancient suture zone between the Tell Atlas and the Tunisian Platform and has produced multiple moderate events over the past century.

The Saharan Atlas in the southwest of Tunisia and the Saharan platform in the south are geologically stable and essentially aseismic. The Gulf of Gabès on the eastern coast sits above the Pelagian Shelf, a broad platform that has experienced occasional moderate seismicity in the offshore zone. A small [[tsunami]] triggered by a submarine earthquake in the Gulf of Gabès in 1948 caused minor coastal damage.

The [[seismic-wave]] propagation characteristics in Tunisia are dominated by the relatively thin lithosphere of the Pelagian Block and the thicker craton to the south. The Africa-Eurasia convergence will continue to generate moderate earthquakes in northern Tunisia for the foreseeable geological future, and cities such as Tunis — built partly on soft alluvial soils of the Medjerda River valley — face amplified shaking hazard from regional events.