Volcanic eruptions
What is a volcanic eruption ?
The Earth’s crust is constantly changing. Although this movement is not visible to the naked eye, rocks shift across the globe. This activity is particularly evident near major geological faults that cross certain regions. These weaknesses allow magma (a mixture of molten rock, gases, and minerals formed by high temperatures underground) to rise toward the surface. During an eruption, pressure allows magma to escape through a crater or fissure, which are openings in the Earth’s surface. Once magma reaches the surface, it is called lava. As it cools and solidifies, it can build up over time to form a volcanic cone, known as a volcano.
Types of volcanic eruptions
Effusive volcano
Causes of rashes regular washing fluid at high temperature (about 1200° C), flowing slowly on the slopes of the volcano.
Explosive volcano
The magma is viscous, a little liquid-rich and gas accumulates in-depth, under the dome, which acts as a " stopper ". When the pressure becomes too strong, the magma is expelled violently, creating large plumes of gas and ash clouds that can take the form of glowing clouds.
Caribbean volcanoes are explosive.
In addition to lava flows and discharges of gas, volcanoes can generate other hazardous weather, such as lahars. A lahar is a mudflow of volcanic : it is formed when water from heavy rains mixed with ash and volcanic debris. The lahars can hurtle down quickly the slopes and cause significant damage in populated areas. https://pirac.croix-rouge.fr/project/que-faire-en-cas-coulee-de-boue-lahar-volcan/
The eruptions marked the history of the Caribbean, check out these past events by clicking here.
The volcanic eruptions in the Caribbean
"The Caribbean region is characterized by significant volcanic activity. This area is known as the Lesser Antilles Arc. Volcanic activity on Earth is driven by plate tectonics and the movement of magma underground. The Earth’s surface is divided into about a dozen tectonic plates that move relative to one another. Their interactions create different geological processes, particularly:"
Convergence Zone
A plaque can dive under another, this is called subduction zones
Divergence zone
The warm material rises to the surface of the earth and pushes the plates
The west indies is a chain of volcanic islands that extends into the Caribbean sea and having been created by the succession of volcanic eruptions from about 40 million years ago.
Diagram of the formation of the west indies ( ©Risque972)
"To the east of the Caribbean Sea, the North American plate (less dense) converges with the Atlantic plate (more dense) and slides slowly underneath it. This process is called subduction. This process takes millions of years and occurs at a very slow speed on a human scale (a few centimeters per year). Geologically, this collision is significant, resulting in a highly active volcanic area. As the oceanic plate sinks into the Earth's mantle, it undergoes
high pressures and temperatures, causing magma to form. This magma then rises to the surface and feeds the volcanoes.
The succession of volcanic eruptions has shaped the development of the West Indies for about 40 million years. Today, volcanic activity continues to shape the Caribbean landscape."
The volcanoes in the caribbean are volcanoes explosive, even if some have been able to exhibit phases effusive.
Source : Booklet teacher, cycle 3 – Project "Pare pa Pare" – French Red Cross – 2022
Map of active volcanoes of the lesser Antilles
For more information :
Redirect links
Risk 972 – Monitoring and Safety Tips Explanation on the phenomenon, the hazards, how to protect themselves and the eruptions in the lesser Antilles (En)
Volcanoes | The UWI Seismic Research Centre University of the West indies explanation on the volcanoes (Eng)
Volcanic eruption | Geohazards Guide and French device on volcanic eruptions – Geohazards(en)
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