Volcanic Hazards Flashcards
What plate margins do volcanic eruptions usually occur?
Constructive and destructive.
Describe pyroclastic flow.
A mixture of super heated gas, ash and volcanic rock that flows down the sides of the volcano and travels at high speeds.
Can cause widespread death and destruction due to their speed.
Describe lava flow as a volcanic hazard.
Flow from a volcano vent down the side of the volcano.
Speed and distance depend on the the temp and viscosity of the lava and the steepness of the volcano.
Most flows are slow giving time to evacuate however it still destroys everything by burning it.
Describe volcanic gases as a volcanic hazard.
Lava contains gases such as CO2 and sulfur dioxide which is released into the atmosphere during eruption.
These can be harmful to humans and animals causing breathing difficulties.
Describe ash fallout as a volcanic hazard.
Ash fallout= material ejected from the volcano during eruption.
Can range in sizes and travel thousands of kilometres away from the volcano.
Can damage buildings, kill or injure people and affect evacuation by blocking roads.
What are the secondary hazards of volcanos?
Mudflows and acid rain.
What are secondary hazards?
Hazards caused by the primary hazard.
Describe a mudflow.
When volcanic material mixes with water and flows very quickly and far.
Can bury or destroy natural habitats and infrastructure.
Describe acid rain as a volcanic hazard.
Volcanic gases react with water vapour in the atmosphere causing acid rain.
Eg: sulfur dioxide reacts with water forming a weak sulfuric acid.
This can damage ecosystems and buildings.
Define how the magnitude of volcanic hazards vary.
Eruptions range from small, slow lava flows to huge eruptions of lava ash and gas.
How is the magnitude of volcanos measured?
Volcanic explosivity index.
How does the frequency of volcanic hazards vary?
Some active volcanos erupt once every 100,000 years whereas others erupt every month. More frequent eruptions are smaller in magnitude.
How do scientists predict the regularity of a volcano?
The regularity of a volcano allows scientists to predict when it might erupt again and monitor changes in the shape of volcano.
What is a mudflow also known as?
A lahars
