Volcanic Eruptions [U1] Flashcards
Types of eruptions, hazards of eruptions
What are the 4 types of volcanoes? (Referring to their shape).
Shield, Composite/Stratovolcano, Cinder
Which types of volcanoes have high or low explosivity?
Shield/Cinder - Low explosivity
Stratovolcano/Composite - High explosivity
What does ‘VEI’ stand for and what is the measuring based on?
VEI = Volcano Explosivity Index
A measure of how much material (ash, lava) is ejected during an eruption
Name in order of explosivity each type of eruption.
Fissure (Icelandic), Hawaiian, Strombolian, Vulcanian, Vesuvian, Plinian
For the following eruption types, explain how the eruption occurs: Fissure (Icelandic), Hawaiian, Strombolian, Vulcanian, Vesuvian, Plinian.
Fissure (Icelandic) - Lava flows through the fissure, non-explosive eruption
Hawaiian - Lava erupts through a vent, non-explosive, some gas escapes vent
Strombolian - Moderately explosive, moderate gas content, pyroclastic flow
Vulcanian - Moderately Explosive, small magma volume, lots of volcanic ash
Vesuvian - Powerful blasts of gas and ash in the sky covering surrounding area, lava flow occurs
Plinian - Extremely explosive, ash columns extend miles, pyroclastic flow
Define the term “Pyroclastic flows”.
Mixture of gas, lava, rock and ash flowing down the side of a volcano.
Define the term “Tephra”.
Pulverised hot rock ejected in the sky.
Define the term “Lahar”.
Mudflow created by heavy rain mixing with ash.
Why are Lahars so dangerous?
Lahars can form quickly and move at very high speeds. It can often carry large debris and other materials that have a powerful impact. Lahars can happen many years after an eruption.
How does a “Jökulhlaup” (Glacier Flood) occur?
It happens when ice and snow on top of a volcano starts melting due to volcanic activity and floods areas below the volcano.
What is a “Debris Avalanche”?
It’s a volcanic landslide caused by an eruption.
