The Caribbean is home to many active and dormant volcanoes. These volcanic centers are primarily concentrated in the Lesser Antilles, a chain of islands forming the eastern boundary of the Caribbean Plate, stretching from the Virgin Islands down to Grenada. This arc of islands is a direct geological consequence of tectonic plate interaction. The region contains 21 identified “live” volcanoes, distributed across 11 different islands.
The Formation of the Lesser Antilles Volcanic Arc
The presence of volcanoes in the eastern Caribbean is explained by subduction, where one of the Earth’s tectonic plates slides beneath another. Here, the oceanic crust of the North American Plate is slowly diving beneath the Caribbean Plate at the Lesser Antilles Subduction Zone. This process is responsible for the formation of the entire Lesser Antilles Volcanic Arc.
As the North American Plate descends into the Earth’s mantle, it carries water-rich sediments and minerals. This water is released under intense heat and pressure, which lowers the melting point of the mantle material in the overlying Caribbean Plate. The resulting molten rock, or magma, is less dense than the surrounding solid rock and rises toward the surface.
This rising magma eventually penetrates the crust, forming the volcanoes that make up the islands in the arc. The islands formed by this process are generally stratovolcanoes, characterized by steep slopes and explosive eruption styles. This ongoing process ensures that the Lesser Antilles remains a geologically dynamic and volcanically active region. The active arc is distinct from the older, inactive volcanic arc of the Greater Antilles, which includes islands like Puerto Rico and Hispaniola.
Notable Active and Historically Eruptive Sites
The Lesser Antilles contains several well-known volcanic centers with significant histories of activity. These volcanoes are a mix of those currently erupting, those showing signs of unrest, and those that are dormant. The region has recorded at least 34 historical eruptions, with 21 occurring since 1900.
Soufrière Hills Volcano on Montserrat is the most famous example of recent, sustained activity. This volcano began erupting in 1995 and has been continuously active for decades, necessitating the abandonment of the island’s capital, Plymouth. Its eruptions are characterized by the slow growth and frequent collapse of a lava dome, which generates hazardous pyroclastic flows.
Another prominent example is La Soufrière, located on the island of St. Vincent, which erupted explosively in 2021, forcing mass evacuations. The name La Soufrière is common for several volcanoes in the region, including La Grande Soufrière on Guadeloupe. Historically, La Soufrière also had a major eruption in 1902, which occurred around the same time as the region’s most catastrophic event.
That event was the eruption of Mount Pelée on Martinique in 1902, which resulted in the destruction of the city of Saint-Pierre and the deaths of approximately 30,000 people. Mount Pelée’s eruption is known for the rapid pyroclastic flows that swept down its flanks, making it one of the deadliest eruptions of the 20th century. Today, both La Soufrière and Mount Pelée are closely monitored and remain at a low-level “vigilance” alert status.
Scientific Monitoring and Hazard Mitigation
A sophisticated system is in place to monitor the Eastern Caribbean’s volcanoes and mitigate risks. The Seismic Research Centre (SRC) at the University of the West Indies is the primary body responsible for monitoring 16 of the region’s 21 live volcanoes. The SRC works in collaboration with local authorities, such as the Montserrat Volcano Observatory, to track signs of volcanic unrest.
Monitoring employs several scientific techniques to detect subtle changes that may precede an eruption. Seismology is a primary tool, using a network of seismic stations to detect and locate small earthquakes associated with magma movement. Scientists also use GPS and tiltmeters to measure ground deformation, which is the swelling or deflating of the volcano’s flanks as magma and gas pressure changes.
The chemical composition of gases and hot springs is also regularly analyzed to track changes in the release of volcanic gases, such as sulfur dioxide. Significant changes in activity are communicated to island governments through their National Disaster Management Organizations. This communication uses a standardized alert level system, typically ranging from green (normal) through yellow, orange, and red, to guide public education and evacuation planning.