Deck 2 - Tectonics: Types of volcanoes and hazards Flashcards
What is a composite volcano?
Volcano made of alternating layers of lava and tephra from previous eruptions
What is a shield volcano?
A type of volcano built entirely or mostly from fluid lava vents. They are relatively wide and low in elevation hence their name
What is a cinder cone volcano?
A steep conical hill shaped volcano that is made of volcanic debris (tephra) that accumulates around and downwind from the vent.
What type of eruption is this?
It is an explosive eruption as large amounts of hot tephra and gases have been released.
What type of eruption is this?
It is an effusive eruption as the eruption is characterised by basaltic lava flowing down the volcano. There is a small amount of ash released.
Which type of volcanoes are associated with effusive eruptions?
Shield and hotspot
Which type of volcanoes are associated with explosive eruptions?
Composite volcanoes
What is a hotspot volcano?
A hotspot volcano forms above a mantle plume. As the plate moves across the mantle plume the volcano becomes extinct and over time a volcanic island arc is created.
What is a pyroclastic density current and what sort of volcanoes do they occur at?
A current that is made of hot ash, gases and volcanic rocks that travels down the volcano rapidly. They occur during explosive eruptions at composite volcanoes.
What volcanic hazards are present in this eruption?
Visible- Ash fall, pyroclastic current
Also likely/possible- lava flow (viscous so stayed near crater), toxic gases, lahar (if it rains)
What is a lahar and how do they form?
A lahar is a destructive mud flow that is made of volcanic ash that has mixed with water (either from rainfall or snowmelt).
What is a jokulhaup and how do they form?
A jokulhaup is a glacial flood that forms when a subglacial volcano erupts and the heat of the eruption melts the ice creating a large flood.
What risk do lava flows pose?
Smaller risk to human life as lava flows are generally slow enough for humans to move away from. However, large risk posed to immoveable objects such as buildings, infrastructure and the natural environment.
What risks does volcanic ash pose?
Ash can easily be inhaled which can suffocate people/animals. The build up of volcanic ash on buildings and infrastructure can cause it to collapse due to its weight. Finer volcanic ash can travel large distances and destroy crops and cause disruption to air travel.
What risks do toxic gases pose?
Toxic gases that include chlorine, fluorine and sulphur and kill people if large quantities are inhaled. In smaller concentrations they can irritate eyes and skin.
