Life in paradise can be hard. Paradise is a Greek word of Persian origin made famous by the Jewish bible: it comes from a mix of very different cultures. The word means a walled garden. The garden provides food and the wall provides safety: together it makes the perfect refuge from normal life. And isn’t that what a garden still means to us? The Septuagint, the Greek translation of the bible, used the word both for an orchard and for the Garden of Eden.

Nowadays, we often associate paradise with tropical islands, where plants grow in abundance year-round and where the sea provides the isolation and security that seems so desirable. It is a place far from the conflicts of the world. But it overlooks the stifling heat, the punishing droughts, the teeming insects, the hurricanes. Life in paradise is not easy. I remember an old man sitting in a small holding of maize, ready to chase away the raiding monkeys, amidst a crop of plants that all seemed to already have succumbed to the drought and heat; the old man was safeguarding a crop that would never ripen. That too is life in the tropics.

The Atlantic ocean has a number of those paradisiacal tropical islands. Some are little known, such as Fernando De Noronha, a small archipelago of volcanic rocks of the Brazilian coast. Ascension Island and Saint Helena are two other ones, albeit more desert than paradise. Closer to Africa, the Cape Verde islands and Sao Tome and Principe fit the expectations of a tropical paradise better. All of these islands are volcanic, as deep-sea islands normally are. But most often, when people are taking holidays to tropical islands in the Atlantic basin, they travel to the Caribbean. There are over 7000 islands here spread over 26 separate nations. But, despite the promise of a paradise holiday, life on the islands is not for the faint-hearted, with devastating hurricanes (of increasing strength), earthquakes, potential tsunamis – and volcanoes.

The Caribbean Sea and plate

The islands of the Caribbean form distinct groups. In the north are the islands of the Greater Antilles, which includes the large islands, from Cuba to Puerto Rico and the Virgin Islands, which appear as an extension of the Yucatan peninsula. (Many of the 7000 islands are associated with Cuba.) South of these are the Lesser Antilles. These include a chain of smaller islands stretching to the coast of South America from Saint Martin to Grenada, and a group of islands along the Venezuelan coast, from Tobago to Aruba. Finally, there is a group of islands north of Cuba known as the Bahaman archipelago.

The Caribbean is more than just a series of islands. The Caribbean Sea covers the entire region from the islands to Central America, and from Cuba to the Yucatan – although it excludes the Bahamas. Much of the sea is 5-8 km deep. The deepest part is the Cayman trench, at more than 7.5 km. The Puerto Rico Trench just north of this island is even deeper, but it falls outside of the boundaries of the Caribbean Sea. , A region between Honduras and Jamaica is much shallower and divides the sea in two

The region has a rather complex geology. The part of the Caribbean Sea north of Honduras and Jamaica is located on the North American plate. This includes the deepest parts of the Caribbean Sea, reaching over 7.5 km in the Cayman Trench. The area south of Jamaica forms its own plate, indeed named the Caribbean plate. One can argue about this name, since it does not cover the entire Caribbean Sea, includes part of continental Central America and its shelf, and even extends slightly into the Pacific ocean. The plate is mainly oceanic (in spite of being named a ‘sea’). It includes four oceanic basins: the Colombian Basin, the Venezuelan Basin, the Granada Basin and the small Tobago Basin, where the first two reach some 5.5 km deep. This depth shows that the oceanic part of the plate is mature but not ancient. (Fresh oceanic crust is less deep whilst 6km is average for older oceanic crust.)

Small plates make large boundaries. The Caribbean plate borders the North American plate, the South American plate, the Cocos plate and the Nazca plate or the Panama micro-plate depending on which paper you read. Along the northern boundary, the plates have fragmented, forming the Hispanola microplate and several even smaller fragments. Each boundary acts different. This is a geo-mess.

On the Pacific side, the Cocos plate is subducting underneath the Caribbean and the North American plate. An active volcanic arc follows this subduction zone, stretching from the Mexican border to Costa Rica. Here are the famous volcanoes of Guatemala and Nicaragua. One of the largest eruptions of the 20^th century (remember that one, before the invention of the mobile phone changed everything?) occurred here: this was the Santa Maria explosion of 1902. The volcanic activity lessens towards the south, but even Panama has some volcanoes. This all acts as a normal subduction zone.

The Nazca plate boundary behaves a bit different. This is another large plate which follows much of the coast of South America where it subducts vigorously. (If you are interested: it is a surviving part of the Farallon plate, now lying underneath North America.) But along the Caribbean plate it does not subduct: the boundary here runs east-west and this is also the direction of movement of the plate, causing transform motion. Along this border lies a fragment that has split off from the Caribbean plate, known as the Panama (micro)plate. This was originally a volcanic arc, caused by the Nazca subduction, but it started to move independently and is now moving northwestward. This movement, no doubt caused by pressure from the Nazca plate, ended the subduction and is the reason why Panama, in spite of its volcanic origin, has dropped down the volcanic rankings. The Cordillera Central of western Panama contains the remains of the volcanic arc. Volcan Baru is still active – and dangerous.

The Caribbean plate is now interacting with its Panamian offspring. This is mainly a passive, diffuse boundary: parent and child get along reasonably well. There is a bit of transform movement where the Panama plate moves eastward (causing the funny shape of Panama in the process), and a bit of thrusting where the two move into each other and which has helped pushed up the sea floor north of Panama.

Further east, the Caribbean plate borders Colombia and Venezuela, stretching to Trinidad and the Orinoco river. This is a so-called transpressional zone, a zone that has both transform motion and convergence. This is not an easy movement to accommodate, and the fault zone has separated into two. In-land in Venezuela runs a transform fault, called the El Pilar fault zone. It is a right-lateral fault, meaning that if you stand facing the fault, the opposite side is moving to the right: the Caribbean side is moving eastward relative to South America. The fault zone runs from west of Caracas to Trinidad. The transform motion is a few mm per year, which is less than a tenth of the movement on the Cocos plate subduction.

Still, the El Pilar fault system is capable of large earthquakes. Caracas was destroyed by an M7.5 (est.) in 1812 and was again but less severely damaged by a similar-sized event in 1900. An M7.3 earthquake hit further east in 2018. The last significant earthquake in Caracas was in 1967 (M6.6), long enough in the past that the city should be prepared for a recurrence.

The El Pilar fault system does transform motion. The compression component is accommodated further north. The northern coast line of Venezuela has accreted fragments from the Caribbean Sea, and these have been uplifted by the compression. There isn’t a well-developed fault line but some ancient lava flows that were formed under water have now been uplifted above it, affecting the arc of islands from Aruba eastward. It is not particularly active but there are occasionally minor earthquakes in the region. But off the coast of Colombia, the effect is a bit different and here, east of Colomobia’s Santa Marta fault, the Caribbean plate actually subducts underneath the accretionary block on the coast.

The northern boundary of the Caribbean plate is just as complex, and even more so when including the Caribbean Sea further north. This is paradise at its worst.

The islands of Jamaica and Hispaniola (home to Haiti and the Dominican republic) lie at the end of the Nicaraguan rise, the one that starts from Honduras. The northern edge of this rise marks the boundary of the Caribbean plate: it runs north of Jamaica and along the southern coast of Hispaniola. This edge is a transform fault where the Caribbean plate moves eastward. The fault is known under many different names, including the Walton Fault zone and the Swan Islands Fault Zone (same fault, different place) to the west of Jamaica and as the Enriquillo-Plantain Garden Fault Zone at Haiti. The devastating 2010 Haiti earthquake took place on this fault, when perhaps 150,000 people died (the true number is not known); Haiti has never really recovered from it.

About 100 km north of this fault lies a second fault, known as the Oriente Fault Zone west of Cuba and the (hold it) Septentrional Fault Zone further east. (This is not the most memorable name in history – perhaps we should find someone willing to lend their name to a fault.) (I am not going to mention it.) USGS calls the combination the Septentrional-Oriente Fault Zone which does not sound like an improvement. The fault zone runs along the southern edge of Cuba and the northern edge of Hispaniola. There are regular earthquakes along this fault as well, including the 1766 M7.6 Cuba earthquake and the M6.8 in the same location in 2024. Haiti’s record event, the M8 earthquake in 1842, was also on this fault line. North of this fault lies the Cayman Ridge.

Further northeast, on the other side of Cuba, lies yet another fault, with perhaps the most complex name of all: it is the North Hispaniola Deformed Belt-Puerto Rico Trench. (Yes, that is all one name.) It begins near the Bahamas and runs east from there. Around Cuba and Hispaniola it is a thrust zone, but around Puerto Rico it becomes an oceanic trench and subduction zone.

There is more. Between the Cayman Ridge and the Nicaragua Rise is the Cayman Trough, which contains the deepest part of the Caribbean Sea. This is at the southern edge of the North American plate; the trough runs between Hispaniola and southern Mexico, sandwiched between the two faults.

Midway along its length lies a ridge which connects the southern and northern fault. This ridge is a short spreading centre. The trough east of this spreading centre, plus the adjacent island of Hispaniola, is considered an independent plate, called the Gonâve microplate. The Cayman trough is the remnant of an older subduction zone, where the Caribbean plate subducted underneath North America. It became inactive but did not disappear.

The eastern boundary of the Caribbean plate is easier. Here, the Puerto Rico Trench bends around the arc of the Lesser Antilles. There is a proper subduction zone where the Atlantic Ocean dives underneath the Caribbean plate. Indeed, the Lesser Antilles here form a volcanic arc with 16 known potentially active volcanoes. The relative speed of the two plates is quite small for a subduction zone, at roughly 2 cm per year. This is no Indonesia. Still, there is enough magma production for some volcanic activity. And there are earthquakes. The largest reported one was in 1843 in Guadaloupe which may have been M7.5 or more. (The value of M8.5 that is often quoted seems inconsistent with the lack of major tsunamis across the Atlantic.) The region experiences an earthquake around M7 perhaps once per 20 years, most recently in 2007 in Martinique.

Altogether, the Caribbean plate is a small version of the Ring of Fire. It is surrounded by two major earthquake zones and two major volcanic zones – both of which can also do earthquakes. This paradise really is a walled garden.

History

The Caribbean plate seems a strange inclusion in the Atlantic ocean. The Gulf of Mexico isn’t a separate plate, nor is the northern Caribbean Sea, so why is the Caribbean plate here? It is not a recent addition: it seems to have a similar age as the Atlantic ocean itself. There is ancient lava here, of two different origins. The first is an old volcanic arc that follows the current line of the Greater Antilles and the Lesser Antilles and which has left its remnants on and underneath these islands. It dates to the early cretaceous, perhaps 120 million years ago. The second one is a flood basalt 90 million years ago which formed the Caribbean Large Igneous Province (CLIP) and which is found throughout much of the region, including Jamaica.

There are two models for the origin of the Caribbean plate. One is that it always was where it is now, sandwiched between the Pacific and Atlantic oceans. The other model places it as originally part of the Pacific ocean. This second model is now seen as most likely. The CLIP deposits are one of the reasons for this. The isotopic composition of the lavas and the age indicate a possible relation to the Galapagos hot spot – and this has always been in the Pacific ocean. The basalts must have drifted with the Pacific ocean floor towards the east.

A second reason stems from magnetic anomalies have been found in the basins of the Caribbean plate. The distance between the anomalies, together with their ages, gives a spreading rate. This comes out a rate of 30 mm per year. At this rate, the plate again must have formed in the Pacific ocean. The Caribbean plate would have formed at a Pacific spreading centre from 120 million years ago, and arrived at its present location between the America some 60 million years ago and more or less remained there.

In this model, the Caribbean plate is a survivor of the Farallon plate. Hence, the Nacza, Panama and Carribbean plate are descendants from the same parent.

There are many unsolved problems. The old volcanic arc of the Greater Antilles suggests there was a subduction zone. But where was this? Why did the plate become stationary? And what made the plate move this way, if there were spreading centres in both the Pacific and Atlantic ocean?

This last point is a significant problem. Spreading centres form when the oceanic crust is pulled apart in opposite directions, a bit like tearing a piece of paper by pulling on both sides. The pull comes from subduction zones. Without the distant subduction, there is no space for new crust to move into. How does this work with spreading centres on either side and the oceanic crust still too young to easily subduct?

There are ways around this. Younger oceanic crust can do through flat-plate subduction. The continental crust moves underneath a continent but does not subduct deeper. This creates space by, in a way, double dipping. A second way is to postulate an unusually warm mantle. This allows the oceanic crust to subduct at a much younger age than would normally be the case.

There may even be a third way. Around 120 to 100 million years ago, the north-central Atlantic ocean was opening up but South America was still joined to Africa. The effect was that South America was moving south and the new ocean between North and South America was growing larger. This growth may have caused space for the Farallon plate to move into. By 60 million years ago, the space was full. The spreading centre in the Farallon plate may have jumped west, and plate movements changed. Perhaps this was when the Caribbean plate separated from the Farallon plate and became the full owner of its own space, neither enslaved to the Atlantic nor the Pacific, neither North nor South America, but pure Caribbean. I like the idea. But there is much research still to be done before we really understand the Caribbean, where the world mixed and created a new, independent paradise.

Volcanoes of the Caribbean

There are around 15 to 20 active volcanoes here, of which 8 have erupted relatively recently. All are located on the volcanic island arc, over a distance of 750 km. The volcanic line is only tens of kilometers wide. Typically, the volcanoes are around 1 km tall: don’t expect hawaiian giants here!

From north to south, they are found on the following islands:

Saba is a small island consisting largely of one volcano: Mount Scenery. The name is nice, the volcano is not. It had an eruption around 400 years, a large eruption 5000 years and a seismic swarm in 1992. The main town, called The Bottom (don’t ask) was build on the pyroclastic deposits of the eruption that likely occurred a few decades before.

Sint Eustatius has a small volcano called The Quill. It formed in a large event over 20,000 years ago, and had a largish eruption around 1600 years ago. The topography can focus pyroclastic flows towards the capital, Oranjestad. This is not a safe mountain.

Saint Kitts and Nevis are two separate islands with one name. They own two volcanoes, Mount Liamuiga and Nevis Peak on Nevis. Mount Liamuiga is at the northern end of Saint Kitts. It is also known as Mount Misery. There is an impressive 1-km wide crate on the summit. The appearance is that of an active volcano, and indeed it has erupted with VEI 4’s 2000 and 4000 years ago. Mount Verchild is also volcanic but is extinct. Nevis Peak is considered potentially active because of fumaroles and hot springs but there are no known eruptions

Montserrat is known for the Soufriere Hills. It was in an active phase between 1995 and 2010, with several large eruptions since. It builds and explodes lava domes. The capital, Plymouth, was badly damaged in 1997. Much of the population of the island has been evacuated. Three more volcanoes are listed on the island but without recent activity; these may be extinct.

Guadeloupe consists of two parts, Grande-Terre and Basse-Terre. If you are tempted to buy property here, go for the former which is away from the volcanic line. Basse-Terre has La Grande Soufriere (Soufriere means sulphur) on the southern side of the island. It had a significant eruption 500 years ago. The major earthquake in 1843 (already mentioned) also caused an explosive eruption at this volcano. However, although the 1500 casualties on the island are sometimes attributed to this eruption (as in the wikipedia page of the volcano), they were in fact due to the earthquake and tsunami. The most recent eruption was in the 1970’s.

Dominica has five potentially active volcanoes, lying along the spine of the island. Morne Watt, on the southern end of the island, is the main attraction, with active thermal areas and a boiling lake. It had a phreatic eruption in 1997 and a larger one in 1880, and there is evidence for a much larger eruption some 1500 years ago. Nearby are two more volcanic peaks, Morne Trois Pitons and Morne Plat Pays, which also had minor eruptions 1000 years. A large caldera formed 40,000 years ago. There are two volcanoes in the north of the island, Morne Diablotin and Morne aux Diables which are potentially active but have not erupted in the past 20,000 years. There are several more extinct volcanic peaks on the island.

(The number of 21 potentially active volcanoes in the Eastern Caribbean listed in places such as wikipedia comes from counting a number of distinct features on Dominica as separate volcanoes. I have not done this here, which reduces the number to 16.)

Martinique has one volcano but it is a very well known one. The 1902 eruption of Mount Pelee destroyed the town of Saint Pierre and killed almost everyone in it. There was a further eruption in 1929. The typical eruption rate is around once per century. It remains well watched and renewed activity would not be a surprise.

Saint Lucia has a single volcanic centre, associated with the Qualibou caldera which formed over 20,000 years ago. It contains lava domes and hot springs, with a phreatic eruption in 1766.

Saint Vincent and the Grenadines are a small island (Saint Vincent) and a series of even smaller ones to the south. There is one main volcano, La Soufrière (a more distinctive name might be helpful), located on the north side of Saint Vincent. It is the most frequently active on-land volcano in the Caribbean, which last erupted in 2021 with a VEI 4. A large eruption on 7 May 1902 caused 1500 fatalities. It happened one day before the catastrophic eruption of Mount Pele on Martinique.

Grenada lies at the southern end of the Grenadines. Although the island is covered in volcanoes, they are not active. Only Mount Saint Catherine is listed as a risk for a future eruption, based on fumarole activity and a scoria cone which may be less than 1000 years old. The main active volcano is a submarine cone 8 km north of the island . It is called, in typical Caribbean fashion, Kick ‘em Jenny. It was discovered in 1939 when an eruption broke the surface of the water, with a small tsunami. It erupts on average once per decade, most recently in 2017. The main risk associated with the volcano is cone-collapse causing a tsunami, but the current size of the cone seems too small for this. A second cone lies 3 km away, and is called Kick ‘em Jack. This peak seems currently inactive.

This gives a total of 16 active volcanoes. You may note that the islands lying just to the east do not have volcanoes. These include St Maarten, Antigua and Barbuda, Barbados and Tobago do not have volcanoes. They are lying on a ridge that is pushed up by the subduction zone. The next series of islands are the volcanic ones. Because of the narrowness of the volcanic zone, this separation is nicely visible.

The following table gives a list of significant eruptions in historical times. It is copied from https://uwiseismic.com/volcanoes/caribbean-volcanoes/ The 1976 eruption led to precautionary evacuations which caused the large economic cost. The eruption indeed happened but was much smaller than had been feared.

Each of these volcanoes is worthy of a VC post!

This is life in paradise. The Caribbean has evolved to become a unique place. It lives in between different worlds and out of this mix, both human and geology, has created a new one. Soehow, the word paradise seems fitting. The Caribbean is a gift.

Albert, January 2026