1 May 2014, Comments: 0
Fact Checked

Volcanic eruptions occur when lava and gas are discharged from a volcanic vent. These typically cause large populations to evacuate away from the area and damage in the surroundings as the lava flows away from the volcano. Another consequence of volcanic eruptions is volcanic ash landslides, also called Lahar. Volcanic eruptions release magma, which is mixture of semi-molten and molten rocks, volatiles and solids located beneath the Earth’s surface. The most dangerous of all volcanic eruptions is called glowing avalanche, where erupted magma that reaches up to 1,200 degrees forms hot pyroclastic flow. Rock fragments succeeding a volcanic eruption surges down the flanks of the volcano at a few hundred kilometers per hours and eventually reaches as far as tens of kilometers from the original disaster site.

Types of Volcanic Eruptions

There are three main types of volcanic eruptions: magmatic eruptions, phreatomagmatic eruptions, and phreatic eruptions. Magmatic eruptions implicate decompression of gas within the magma that causes it to drive forward. Phreatomagmatic eruptions also involves the decompression of gas within the magma, however they are caused by interactions between magma and water. Lastly, the superheating of steam through contact with the magma propels phreatic eruptions. Under the three main types are several subtypes that are usually named famous volcanoes where the type of eruption was observed.

Magmatic Eruptions

  • Hawaiian – calmest type
  • Strombolian – short-lived but explosive eruptions* of intermediately-viscous lava
  • Vulcanian – highly viscous magma  with explosive eruptions* (more explosive than Strombolian)
  • Peléan – large amounts of gas, dust, ash and lava fragments are ejected from the central crater of the volcano
  • Plinian or Vesuvian – highly explosive eruptions

*due to high gas pressure

Phreatomagmatic Eruptions

  • Surtseyan – characterized by shallow water interactions between water and lava
  • Submarine – volcanic eruptions that occur underwater
  • Subglacial – caused by interactions between ice and lava, usually under a glacier

Warning Signs of Volcanic Eruptions

Volcanologists alert the government regarding volcanic activities and advise when there needs to be an evacuation. However, one can also be on the lookout for volcanic eruptions with the following warning signs. These signs may begin to appear weeks to months before eruption is bound to occur.

  • Minor earthquakes beneath the volcano
  • Slight inflation and swelling of the volcano
  • Increase heat and gas emission from the volcano vent

How to Survive Volcanic Eruptions

Evacuation is the topmost priority in cases of volcanic eruptions. The following tips can help increase chances of survival during volcanic eruptions but do not guarantee it.

  • If the lava flow is heading towards a particular location, immediately leave the area. If possible, drive away and keep all doors and windows closed.
  • If one is indoors, close all windows, doors and every possible opening. Switch off fans, air and heating conditioning systems.
  • If one is outdoors, go indoors immediately. If this is not possible, roll into a ball to protect the head in case caught in a rock fall.
  • If one is nearby a river or stream, be wary of rising water and move to higher ground as soon as quickly as possible.
  • Protect self during ash fall by wearing long-sleeved shirts, long pants and goggles. If possible, stay indoors with all windows and doors still closed.
First Aid and CPR classroom where the dangers of natural disasters, including volcanic eruptions, are taught

First Aid and CPR classroom where the dangers of natural disasters, including volcanic eruptions, are taught

It may be difficult to stay calm in cases of volcanic eruptions but it is important not to panic at all times. To learn how to act appropriately in cases of natural disasters such as volcanic eruptions, enroll in First Aid and CPR Courses.

Online Sources

http://www.ifrc.org/en/what-we-do/disaster-management/about-disasters/definition-of-hazard/volcanic-eruptions/

http://en.wikipedia.org/wiki/Types_of_volcanic_eruptions

http://www.livescience.com/8809-scientists-volcano-erupt.html

http://www.bt.cdc.gov/disasters/volcanoes/during.asp

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