Can earthquakes trigger volcanic eruptions?

Earthquakes are not necessarily linked to volcanic activity. Some earthquakes are due to tectonic activity (plates shifting), hence not related to volcanoes, while some others are due to magma trying to find its way up a volcano (volcanic earthquakes). Volcanic earthquake are generally indicative of an increase of volcanic activity but don't necessarily lead to an eruption. Tectonic earthquakes can "shake" a volcano and can potentially help triggering an eruption. However, they can also potentially stop an eruption. No direct links between tectonic earthquake activity and eruptions in the Eastern Caribbean have been found so far.

Can eruptions occur without warning and destroy the entire island?

It is unlikely that an eruption will occur without warning. Volcanic eruptions in the Eastern Caribbean are usually preceded by recognizable symptoms, such as small earthquakes, changes in gas chemistry, and/or ground deformation (swelling of the mountain) long before an eruption occurs. The Seismic Research Centre operates a monitoring system which should enable scientists to provide sufficient warning to the authorities prior to an eruption so that appropriate action can be taken.

Are all the volcanoes in the Caribbean connected so that an erupting volcano on one island will trigger the others nearby?

No, volcanoes in the Caribbean are not connected. Volcanoes on individual islands are formed by the same process, i.e. subduction at the plate boundary, but they do not share the same magma chamber, and are not linked by long underground magma conduits. A volcanic eruption on one island, therefore, cannot trigger an eruption on another island.

If a volcano has not erupted in a long time how do scientists know that it is still ‘live’?

A volcano is considered active (i.e., "live") when signs of activity can still be detected. These signs can be occasional volcanic seismic activity, gas emitted on an around the volcano, ground deformation. Apart from the occurrence of gas vents, most of these signs are generally only detectable with specialized monitoring equipment (e.g., seismometers, GPS).

Do changes in the weather (e.g. a strong heat wave or thunderstorm) signal that the volcano is in a state of unrest and may erupt at any moment?

Volcanoes are caused by processes beneath the surface of the Earth and the factors which may trigger eruptions are totally unconnected to the atmospheric processes which cause changes in weather. Heat waves, overcast conditions at the summit or any other weather phenomena do not indicate anything about the state of the volcano. However, heavy rains during an eruption may trigger mudflows (lahars) and lightening can occur from eruption columns.

Are geothermal features such as steam vents as seen at Sulphur Springs in Saint Lucia and Dominica, actually volcanoes?

Hot springs and fumaroles are not volcanoes. They represent small cracks where hot water and steam escape at the surface. They often occur in volcanic areas, where they can be found in the vent, on the slopes, and in the surrounding countryside, miles away from the volcano! For example, the Sulphur Springs in Saint Lucia is part of the much larger Soufriere Volcanic Centre. It is not the volcano.


Boiling Lake in Dominica. Photo: Göran Höglund