Get a kick | On this day

Kick ’Em Jenny sounds like a comic name, but for the scientists who study this underwater volcano, first recorded eighty years ago, it’s no laughing matter. The Caribbean was shaped by its volcanoes, says James Ferguson, which created our mountainous island landscapes — but can also wreak havoc

  • Illustration by Rohan Mitchell

Blessed by climate and topography, the Caribbean is a region of extraordinary physical diversity. Its economy is determined both by the fertility of its agricultural land and by the beauty of its beaches and mountains, which attracts almost sixty million tourists and cruise ship visitors a year. From the grandeur of St Lucia’s twin Pitons and Guyana’s seemingly infinite rainforest to the rivers, beaches, and tropical exuberance of an island like Jamaica, the Caribbean is testament to the aesthetic power of nature.

Yet nature’s might is not always benign. The Caribbean’s islands and surrounding mainland are regularly ravaged by terrifying hurricanes, most lethal in areas of poverty. With shifting tectonic plates under the Caribbean Sea, earthquakes can wreak havoc: up to 300,000 people are thought to have died during the 2010 disaster in Haiti. And earthquakes produce tsunamis, one of which crashed into the Dominican Republic in 1946, with waves up to five metres high.

One of the region’s most threatening features is also one of its most beautiful: the volcano. Across the Eastern Caribbean, magma has been forced upwards from the seabed by a volatile plate boundary to erupt and create a series of volcanoes. The arc of conical, often forest-clad mountains that define the island landscape is the result of this ancient geological activity. Most appear to be dormant, and are close to towns and villages. The tiny Dutch-administered island of Saba is a single volcano, whose summit, Mount Scenery, is the highest point in the Netherlands. From here down the archipelago to Grenada, visitors can admire the rugged terrain, perhaps oblivious to its destructive potential.

The University of the West Indies’ Seismic Research Centre takes nothing for granted, noting:

There are nineteen “live” (likely to erupt again) volcanoes in the Eastern Caribbean. Every island from Grenada to Saba is subject to the direct threat of volcanic eruptions. Islands such as Grenada, St Vincent, St Lucia, Martinique, Dominica, Guadeloupe, Montserrat, Nevis, St Kitts, Sint Eustatius, and Saba have “live” volcanic centres, while other islands such as Anguilla, Antigua, Barbuda, Barbados, the British Virgin Islands, most of the Grenadines, and Trinidad and Tobago (which are not volcanic) are close to volcanic islands and are, therefore, subject to volcanic hazards such as severe ash fall and volcanically-generated tsunamis.

History certainly suggests that volcanic activity is unpredictable and foolish to ignore. The greatest volcanic disaster in the region took place on 8 May, 1902, killing 30,000 people and destroying the French colonial city of Saint-Pierre in Martinique. The mayor had discouraged the population from leaving, since his re-election was imminent. More recently, increased seismic activity has been recorded in Guadeloupe in the 1970s and St Vincent in 1979 — the latter an event that necessitated the evacuation of 17,000 people — but the most damaging eruption occurred in the British overseas territory of Montserrat in July 1995, when the long-dormant Soufrière Hills volcano abruptly buried the capital, Plymouth, under twelve metres of mud. Fortunately, almost everybody had been advised to leave.

The major volcanoes may now appear quiescent, but seismicity continues unabated across the region. Hot springs are to be found on almost every island, and it is a common claim that you can boil an egg in the streams and ponds close to the volcano site. Soufrières — from the French word for sulphur — are areas where a rotten-egg smell hangs heavy in the air. Carbon dioxide, sulphur dioxide, and hydrogen sulphide often escape from under the earth’s surface through fumaroles, cracks or fissures in old and solid lava flows. The gaseous odour serves to remind us that much is still happening under our feet.

The most recent volcano to be identified in the Caribbean carries the strange name of Kick ’Em Jenny, making an unexpected and dramatic appearance exactly eighty years ago. On 24 July, 1939, an eruption suddenly broke the sea’s surface five miles north of Grenada, shooting a cloud of boiling water, steam, and rocks almost three hundred metres into the air. This submarine volcano — the only one known to exist in the Caribbean — might have erupted before, but this was the first recorded sighting, and probably something of a shock for the fishermen and traders who ply the busy sea route between Grenada and Carriacou. The debris propelled into the air created a series of tsunamis, and waves of up to several metres battered northern Grenada, even travelling as far as Barbados.

Subsequent surveys of the area revealed a structure rising 1,300 metres from the sea floor, with its summit 180 metres below the water’s surface. It is thought that Kick ’Em Jenny is what is left of a much larger predecessor volcano which once stood clear of the sea as an island, but subsequently collapsed during an eruption some 43,000 years ago. Its name was borrowed from an infamously rough stretch of water nearby, but it seemed appropriate, especially when a deep rumbling sound could be heard as far away as Grenada. Explosive eruptions have been recorded twice since 1939, in 1974 and 1988, but persistent seismic disturbances have been monitored, making it not only the most recently discovered but also the most active volcano in the Caribbean.

Volcanologists warn that submarine volcanoes pose a particular threat, as they are hard to monitor and can produce especially violent tsunamis through tectonic movement and “ballistic projectiles.” According to UWI’s Seismic Research Centre, “If Kick ’Em Jenny erupts, it might throw hot rocks up through the water column into the air above the surface of the sea. Such rocks could travel as far as five kilometres from the volcano, and would pose a great danger to nearby ships or boats. Any ship which happened to be over the vent of Kick ’Em Jenny during the 1939 eruption would certainly have been destroyed.”

Although unproven, it has been suggested that this volcano may have caused one of the Caribbean’s unsolved maritime mysteries. Even when quiescent, submarine volcanoes can release large amounts of gas into the seawater in what is called “degassing.” This process lowers the density of the water and radically reduces the buoyancy of any vessel passing over the volcano. The disappearance of the wooden schooner Island Queen on its journey from Grenada to St Vincent on 5 August, 1944, was at first blamed on a German U-boat. Yet no debris or bodies of the sixty people aboard were ever found, fuelling the theory that the boat had lost buoyancy and sunk. “Kick ’Em Jenny had, in fact, erupted the year before (1943), and it is highly likely that it was still actively degassing in 1944, without any signs at the sea surface of such activity.”

So concludes the Seismic Research Centre, and it is hence reassuring to know that it has introduced a 1.5 kilometre maritime exclusion zone from the centre of the submerged volcano, expanding it to five kilometres when heightened activity is detected. It is also some comfort to know that the Caribbean’s volcanologists are experts in their field and can nowadays, as Montserrat demonstrated, predict events with great accuracy.