The string of islands known as the Lesser Antilles stretches
from the margin of the South American continent to the Anegada
Passage in the north, which marks the boundary with the Greater
Antilles Figure 2. The island arc is about
850 km in length and there are a number of active volcanoes
present. These islands have been built up almost entirely by
volcanic eruptions, first on the sea floor as submarine volcanoes
or seamounts, and later to emerge and grow as volcanic islands.
There are at least five islands which currently have active
volcanoes, that is volcanoes which have had historic eruptions
(post-Columbus). The northernmost young volcano in the Lesser
Antilles is Saba, but it has not been active in historic time.
To its south lies the island of St Eustatius, with the Quill
volcano at its southern end, and its activity is also pre-historic
in origin. Similarly, the Mount Misery (Liamuiga) volcano on
the island of St Kitts is also inactive, and so is the Nevis
Peak volcano on the near-by island of Nevis. Further
south is the island of Montserrat, where the Soufriere Hills
volcano has been in a constant state of activity since 1997,
forcing evacuation of much of the island. The Soufriere volcano
on the French island of Guadeloupe had minor steam explosions
in 1976, and must be regarded as an active volcano. Further
south, the island of Dominica has a number of volcanic centers,
but no current activity except for the Boiling Lake. Just south
of Dominica is Martinique, with its ill-fated volcano Montagne
Pelee, which had a devastating eruption in 1902, killing over
29,000 people, and erupted again in 1929-32. The near-by island
of St Lucia has an active hydrothermal field in the Qualibou
caldera, but no current volcanic activity is known. South of
St Lucia is the Soufriere of St Vincent, a volcano that has
erupted violently in 1902, and erupted again in 1971 and 1979.
The southernmost active volcano in the Lesser Antilles arc is
the submarine volcano Kick’em Jenny.
Lesser Antilles are formed where two great crustal plates collide
Figure 3. The North American plate (right)
moves steadily to the west, subducting beneath the Caribbean
plate. Each plate is about 100 km in thickness and they move
at a rate of about 2 cm per year. The interaction of the plates
results in earthquakes (blue, yellow and red dots) and the formation
of magma or molten rock (red) that rises upwards to erupt and
form the Lesser Antilles volcanic islands.
The subduction process introduces water to great depths in the
Earth and this leads to melting of rocks in the Earth’s
mantle, producing the liquid rocks or magmas that erupt to form
the volcanoes at the surface above Figure 4.