Gibraltar

Gibraltar is a British Overseas Territory on the southern tip of the Iberian Peninsula, occupying a narrow limestone ridge at the entrance to the Mediterranean Sea. Its position is seismically significant: Gibraltar sits very close to the diffuse convergent boundary between the African Plate and the Eurasian Plate, which in this region is expressed not as a simple plate boundary but as a broad zone of deformation extending from the Rif Mountains of Morocco through the Betic Cordillera of southern Spain and offshore into the Alboran Sea. The Eurasian-African convergence rate here is approximately 4 to 5 millimetres per year, accommodated across multiple thrust and strike-slip [[fault]]s.

The most historically devastating earthquake in Gibraltar's broader region was the 1755 Lisbon earthquake — estimated at [[magnitude]] 8.5 to 9.0 — which generated a [[tsunami]] with waves of 3 to 5 metres that struck the Gibraltar coast and caused widespread destruction across Iberia, Morocco, and northwest Africa. The event is one of the deadliest in European history. More locally, the 1954 Al Hoceima earthquake in Morocco (magnitude 6.5) and the 2004 Al Hoceima earthquake (magnitude 6.3) were felt in Gibraltar. The region around the Strait of Gibraltar and the Alboran Sea produces multiple moderate-magnitude events annually, and a magnitude 6.3 earthquake offshore in 2016 was felt across southern Spain and Gibraltar.

Gibraltar's compact urban area sits on Jurassic limestone and is largely bedrock, which provides relatively firm ground conditions and limits [[liquefaction]] risk. The Rock itself acts as a geologically stable platform, but nearby Lower Town areas built on reclaimed land are more vulnerable. The British Geological Survey monitors regional seismicity relevant to the territory.