Caribbean Volcanoes: Fire Down Below

Most of the islands of the Lesser Antilles are the products of ancient volcanic activity, evidence of restless forces seething beneath the earth's surface

Scientists from UWI Seismic Research Unit in the field. Photograph courtesy the Seismic Research Unit/ University of the West IndiesSt Lucia’s sulphur springs. Photograph courtesy the Seismic Research Unit/ University of the West IndiesThe entire island of Nevis is  single volcano, with Nevis Peak as its summit. Photograph courtesy the Seismic Research Unit/ University of the West Indies

He was so overcome by the destruction he saw following the eruption of the Soufrière volcano on the island of St Vincent on May 7,  1902 — which killed 2,000 people — and the explosion of Mont Pelée on the French island of Martinique the following day — which sent 28,000 people to their deaths in the town of St Pierre — that he decided to devote his career to the study of volcanic eruptions in order to save lives.

By today’s standards, the deaths due to these two volcanic eruptions could have been avoided. There were ample warning signs beforehand, including a year of earthquakes around Soufrière and minor eruptions from Mont Pelée which increased significantly before the final disaster: a build-up of ash and sulphurous fumes and the collapse of the crater wall on May 5. Rather incredibly, the residents of St Pierre remained in the town in spite of these danger signals, because of an election carded for May 11, and no preparations for evacuations were made. When Pelée finally erupted with powerful pyroclastic flows, St Pierre was destroyed in a few minutes and everybody, except a prisoner in an underground cell, was killed instantly.

Professor Jagger founded his observatory in Hawaii, where the Kilauea volcano was suitable for continuous study, and he initiated the development of monitoring devices and strategies, so that such destruction should never happen again. Up to the present day, HVO continues to monitor the volcanic activity of the Kilauea volcano.

In the Caribbean, the Seismic Unit of the University of the West Indies, based in St Augustine, Trinidad, which was founded 50 years ago, carries out a similar monitoring of earthquake and volcanic activity in the region. The Unit receives financial support from the territories of the English-speaking Lesser Antilles: Trinidad and Tobago, Barbados, Grenada, St Vincent and the Grenadines, St
Lucia, Dominica, St Kitts and Nevis, Antigua and Barbuda, Montserrat and the British Virgin Islands. It provides the governments of these countries with accurate and up-to-date information about local earthquakes and volcanic activity.

Today, with the exception of the still-active volcano in the Soufrière
Hills in Montserrat (which started erupting in 1995, devastating about two thirds of the island), the underwater volcano Kick ’em Jenny off the north coast of Grenada, and some rumblings in Dominica, the Caribbean volcanoes are quiet. They serve as tourist attractions to which luxurious tours are arranged by an enterprising inhabitant of Montserrat, who claimed that “but for the grace of God” he too would have perished on June 25, 1997, when 20 people died.

His experience led him to produce an educational video in collaboration with Professor Steve Sparks of Bristol University. He felt there was a need to instruct geology students about Montserrat’s volcano, and that the video would also be useful for students of earth science. The video deals with the hazards around volcanic activity. Although people are often understandably unwilling to leave their homes and carefully husbanded possessions, the risks involved in staying in unsafe areas are now fully documented.

As you look down at the tranquil, beach-rimmed Caribbean islands through the window of your plane, you may wonder at the turbulence which has shaken so many of these volcanic islands since they were first thrust up through the blue Caribbean Sea. You are reminded that the Earth roils hotly below its surface, with an energy constantly seeking release from pent-up pressures. This release is found at the edges of the 11 large tectonic plates which make up the Earth’s crust. These plates, constantly moving and grinding against each other as they ride on top of the Earth’s molten interior, provide pressure releases in the form of earthquakes and volcanoes. As molten rock is erupted as magma, lava, fragmented rocks and gases, new material rises up through rifts in the sea floor to cause sea-floor spreading, which was initially responsible for the formation of the three major ocean basins, the Atlantic, the Pacific and the Indian Oceans.

Activity along the tectonic plates often produces long lines of regularly spaced volcanoes in the form of conical islands, as occur in the Caribbean. The Lesser Antilles on the south-eastern edge of the Caribbean Sea are volcanic islands formed millions of years ago when the tectonic plate on which North America sits (the North American Tectonic Plate) slid underneath the adjoining Caribbean Tectonic Plate. That sliding motion still continues. This motion is responsible for earthquakes and vents of sulphur and steam along the chain of islands. (“Soufrière”, the name of several Caribbean volcanoes, means “source of sulphur”.) In St Lucia, tourists enjoy the health benefits of the local sulphur springs, and an enterprising entrepreneur makes “healthy soap” from black iron sulphide — rich mud.

It is said that the Arawaks and Caribs worshipped their “Fire God”, the volcano; according to local legend, the Caribs of St Lucia threw human sacrifices into the volcano. Today, some hope to use volcanic steam vents to generate energy. There is little doubt that the islands of the Caribbean, with their fascinating history and
interesting geology, are among the Earth’s most interesting stomping grounds.