Geothermal Activity Status in the Volcanic Caribbean Islands

Abstract

The Atlantic Crustal Plate is subducting westward beneath the Caribbean Plate resulting in formation of volcanic island chains that comprise: 1) an eastern, eastward-convex arc of older, extinct volcanoes and 2) a western arc of younger, dormant to active volcanoes. The two arcs join at Martinique and from there trend southwestward into the Paria Peninsula of Venezuela.

Geothermal indicia including warm to hot springs, fumaroles, solfataras and mud pots exist, to varying extents, on Saba, St. Eustatius (Statia), St. Christopher (St. Kitts), Nevis, Montserrat, Guadeloupe, Dominica, Martinique, St. Lucia, St. Vincent and Grenada. Volcanic eruptions and associated geothermal phenomena have been documented on Montserrat, Guadeloupe, Dominica, Martinique, St. Vincent, Grenada and Kick-em-Jenny (a highly active seamount north of Grenada).

Geothermal resource surface temperatures in the Lesser Antilles islands range from tepid to above boiling (superheated). Subsurface temperatures high enough to support utilization of a double flash energy conversion system have been recorded in the wells drilled for the 4.2 MW La Bouillante power plant on Guadeloupe while temperatures up to 214oC were measured in wells drilled near SoufriËre, St. Lucia.

Prior to 1995, geothermally oriented geologic, geochemical and geophysical studies were conducted on Guadeloupe, Dominica, Montserrat, St. Lucia and Grenada. Ten 500 meter deep wells were drilled at Watten Waven in Dominica; large diameter wells were drilled on Guadeloupe in 1982-1984 and two deep exploration wells were drilled in St. Lucia in 1984- 1987.

Between 1995 and 1999, Caribbean geothermal activity was confined to prefeasibility and feasibility studies conducted on St. Vincent, Saba, Statia, St. Kitts and Nevis. The work included geologic, geochemical and some geophysical studies plus the acquisition of much non-resource related information. Though the signing of Power Purchase Agreements between utility companies, local governments and private developers has been reported on St. Vincent, Dominica and Grenada, to date no wells have been drilled.

Low temperature geothermal waters are informally used for bathing on several islands and bath houses have been built on St. Lucia and Nevis. Otherwise, geothermal fluids are not being used.