pyroclast to strombolian eruption


The eruption of La Palma volcano it has brought with it geological concepts unknown to those who do not deal with it regularly. We frequently hear words like lavage, pyroclasts, fumarole, smoke plume, or strombolian eruption to explain the behavior that the only active volcano in the Canary Islands today.

To make it easier to understand the various words used by experts and that have been generalized for more than a month in the news media on a daily basis, the National Geographic Institute (IGN) picks up a glossary of volcanic terms to consult. The eruption of the volcano lasts more than a month and it is not known when it will go out, so it is convenient to familiarize yourself with these concepts.

These words help us to know exactly what is happening on La Palma and what are the consequences from now on of the orographic change that the volcano is causing in the Aridane Valley. These are the most common concepts that IGN facilitates:

  1. Crater: depression in the shape of a circle that originates from an explosion, it is almost always associated with a chimney through which the volcanic material comes out. It can be tens or hundreds of meters in diameter and depth.
  2. Strombolian eruption: small explosions with eruptive columns that can reach 15 kilometers in height.
  3. Effusive eruption: it is characterized by the expulsion of low viscosity lava, little ash production and a low gas content.
  4. Tremor: the constant vibration and noise caused by the movement of magma as it rises to the surface through a volcano.
  5. Volcanic Explosivity Index (IEV): is an 8 degree scale that volcanologists use to measure the magnitude of a volcanic eruption. It is obtained from several measurable or appreciable elements of volcanic activity.
  6. Cone: or volcanic building. It is the mountain that is formed around the chimney of the volcano with the material that it expels. The cone is forming and deforming every day. It is constantly changing. When talking about hypothetical tsunami that would occur as a result of the eruption in the Cumbre Vieja area on La Palma, the approach starts from the collapse of the volcanic cone with subsequent landslide that would fall on the sea raising large waves that would reach the coasts of the American continent.
  7. Fumarole: a point of emission on earth where steam and other gases come out, they may be located in the crater and their existence may indicate that the volcano is still active.
  8. Plume: also known as an eruptive cloud. It is the plume of smoke from the volcano, formed from the expulsion of gases, ash and fragmented incandescent material that is released into the atmosphere during an eruption. If this material has enough energy and volume, it can reach a height of several kilometers in the stratosphere where the winds can carry it long distances.
  9. Magma: mixture of melted rocks and gases. They can be stored in depths of a few kilometers and their exit to the earth’s surface gives us a volcanic eruption.
  10. Wash: magma that rises to the surface during the volcanic eruption.
  11. Wash: effusion of lava on the surface that starts from a fracture.
  12. Pyroclasts: fragments of lava that are expelled into the atmosphere during the volcanic eruption, can be of different sizes and consolidation.
  13. Volcanic bomb: fragment of liquid or semi-liquid rock that is expelled from the emission mouth during the eruption. It can be several centimeters in diameter.
  14. Lapilli: small, rounded fragments of rocks that can measure up to 5 centimeters in diameter and that are expelled in a liquid or solid state during an eruption. It is what in the Canary Islands we also call irritation or rofe. This last term is more typical of Lanzarote.
  15. Ash: very fine particles of pulverized rock that are emitted during the volcanic eruption. They are less than two millimeters in diameter and can be solid or liquid.
  16. Tephrite: it’s a type of pyroclast or tephra, that is, a volcanic igneous rock whose mineral composition contains titanoaugite, feldspathoids and calcium-rich plagioclase. These compounds are responsible for its dark gray color, one of the clues we have to recognize it if we see it. Its presence in the La Palma volcano indicates that magma has been evolving under the island’s subsoil for thousands of years.
  17. Fajana: land reclaimed from the sea by lava flow. This space has other names, such as low island and lava delta, the latter due to its resemblance to a river mouth delta.
  18. Kipuka: islands of land that remain in the middle of the volcanic flows.
  19. Volcanic rays: They are produced by friction between the rocks ejected by the volcano, which are thrown at high speed, as they rub against each other and produce charges of electricity.
  20. Volcanic tube: volcanic cave in the form of a tunnel that is generated inside a flowing lava flow as it runs down a slope towards the sea. The part of the laundry in contact with the air cools and solidifies, while inside the lava continues to advance and creates the tube.

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