Dominica

Dominica is the most volcanically active island in the Lesser Antilles, crowned by the Morne Trois Pitons volcano complex and containing no fewer than nine potentially active volcanic centres. Its seismicity is therefore a mixture of tectonic earthquakes generated by the Lesser Antilles [[subduction-zone]] and volcanic-tectonic earthquakes generated by the movement of magma and hydrothermal fluids through the volcanic system. The North American Plate subducts westward beneath the Caribbean Plate along the Lesser Antilles arc at roughly 2 centimetres per year; Dominica sits directly above the volcanic front where slab-derived fluids generate partial melting in the mantle wedge. Shallow crustal earthquakes associated with the volcanic system and hydrothermal activity are frequent and sometimes felt by residents. The island's steep terrain and saturated volcanic soils make it highly susceptible to earthquake-triggered landslides. [[tsunami]] exposure from great earthquakes on the adjacent [[subduction-zone]] is a persistent long-term concern.

Historical records from Dominica note significant felt earthquakes throughout the colonial period, though the island's small population and limited built environment meant casualties were rare. The 1974 Antigua earthquake was widely felt in Dominica. The 29 November 2007 Martinique earthquake (magnitude 7.4), which occurred on the [[subduction-zone]] interface approximately 80 kilometres to the north, was strongly felt in Dominica and caused minor damage to older masonry structures. Volcanic earthquake swarms occurred in 1974, 2001–2002, and multiple times in subsequent years, reflecting unrest in the Wotten Waven and Boeri Lake geothermal fields. In December 2021 and early 2022, a significant swarm of more than 700 small earthquakes occurred beneath southern Dominica, raising concerns about volcanic system reactivation though eruption did not follow. The island's most severe natural disaster history has been from hurricanes rather than earthquakes, but seismic hazard remains real and increasing with the volcanic system's activity.

Dominica's geological character derives entirely from its position above the Lesser Antilles subduction system. The island is entirely volcanic in origin — there is no pre-volcanic basement exposed at the surface — and the volcanic stratigraphy records cycles of eruption and erosion over the past several million years. The presence of abundant hot springs, fumaroles, and the world's second-largest boiling lake (Boiling Lake) testifies to a vigorous hydrothermal system fed by the same magmatic heat sources that drive seismicity. Unlike older, more eroded volcanic islands to the north, Dominica retains fresh volcanic topography with steep calderas, pyroclastic deposits, and recent lava flows. The [[subduction-zone]]-generated [[seismic-wave]]s that periodically shake the island travel up through the volcanic crust from a region approximately 100 kilometres to the northeast, where the subduction interface lies at depths of 30 to 60 kilometres.