British Virgin Islands

The British Virgin Islands (BVI) occupy a critical tectonic junction at the boundary between the Greater Antilles to the west and the Lesser Antilles to the south, in the northeastern Caribbean. The territory straddles the Anegada Trough — a deep submarine valley and active fault zone running east-west between the Virgin Islands platform and the Sombrero Bank — which represents a transform or oblique extensional structure associated with the broader Caribbean-North American plate boundary system. North of the BVI, the Puerto Rico Trench marks the zone of [[subduction-zone]] of the North American Plate beneath the Caribbean Plate. The Anegada Trough itself has generated significant historical earthquakes and represents a major seismic source for the territory. The combination of the northern subduction system and the Anegada Trough fault zone places the British Virgin Islands in a high seismic hazard zone within the Caribbean.

The historical earthquake record of the British Virgin Islands is dominated by two major events. The 1867 Virgin Islands earthquake (magnitude 7.5) struck in November with an [[epicenter]] near St. Croix in the Anegada Passage; the earthquake generated a significant [[tsunami]] with reported wave heights of 3 to 4 metres that devastated coastal communities in Saint Thomas, Saint Croix, and Tortola, killing dozens of people and destroying wharves, buildings, and vessels. The 1843 Guadeloupe earthquake (estimated magnitude 8.0) was also strongly felt throughout the Virgin Islands and caused structural damage. In the instrumental era, the BVI has experienced numerous felt events from both the Puerto Rico Trench subduction system and local Anegada Trough faulting. A magnitude 6.4 earthquake in August 2018 near Tortola caused significant structural damage and was widely felt.

The BVI's geology consists of Cretaceous volcanic and plutonic rocks — including the distinctive granodiorite of Virgin Gorda — overlain by Quaternary coral reef and marine deposits on the coastal margins. The Drake's Passage, Anegada Passage, and surrounding submarine topography reflect the fault-controlled structure of the Anegada Trough. The territory's [[tsunami]] exposure is among the highest in the Caribbean for its size, given the proximity of the Anegada Trough fault system and the Puerto Rico Trench. Earthquake monitoring in the Virgin Islands is shared between the Puerto Rico Seismic Network (PRSN) and the University of the West Indies Seismic Research Centre, providing real-time detection capability.