Volcanoes
About Volcanoes
Volcanic eruptions are one of Nature’s greatest spectacles. Yet for those living near a ‘live’ volcano, an eruption can be very dangerous and can pose serious threats to the population. The fiery ash and rock that can explode from a volcano can, in mere minutes, transform the landscape around, rendering once inhabited areas completely unrecognizable.
The tectonically active setting of the Eastern Caribbean lends itself to a host of natural phenomena including volcanoes, which can erupt at any time. As our cities and towns grow, we increase our exposure to the impacts of a volcanic eruption. In the Caribbean, we should all be aware of the ‘live’ volcanoes that might affect us. Identification of natural/geological hazards is the first step in reducing our exposure to and risk of disasters from natural events.
Volcanoes in the Caribbean
Volcanoes are vents or openings in the Earth’s crust through which, gases and hot, molten rock (magma) from the interior of the Earth are released. When magma reaches the Earth’s surface it is called lava and sometimes, but not always, the solid parts of this lava accumulate around the vent to form a volcanic mountain. Some volcanoes are literally slits or holes in the ground while others are broad mountains with gentle slopes.
Volcanoes in the Eastern Caribbean are mainly steep-sided and roughly conical in shape. They consist of alternating layers of solid lava and broken fragments of lava called pyroclastic rocks. Since they are layered, they are called stratovolcanoes.
Birth of an island chain
According to the Theory of Plate Tectonics, the Earth’s crust is made up of huge slabs of rock called tectonic plates, which fit together like a jigsaw puzzle. These plates are constantly moving relative to each other. The area where the plates meet is called a plate boundary and much of the Earth’s seismic and volcanic activity occurs along plate boundaries.
In the Eastern Caribbean, the Caribbean and North American plates are colliding and the North American plate, which is the denser of the two, sinks beneath the Caribbean Plate. This process is called subduction. As the North American plate descends into the Earth, rising temperatures cause the rock to partially melt, forming magma. Magma is more bouyant than the surrounding rock and over time it rises to the surface of the Earth, where it erupts and may form a volcano. It is believed that this is how the islands of the Eastern Caribbean (Lesser Antilles) were formed through countless eruptions over millions of years.
