Volcanoes Flashcards
What are the three main types of volcanoes?
Shield volcanoes, stratovolcanoes, and cinder cone volcanoes. Each type has its own unique characteristics and eruptive behaviors.
Whats a shield volcano?
A shield volcano is formed by repeated eruptions of fluid lava that flows easily and spreads out over a wide area. (Shield volcanoes are known for their relatively calm eruptions.)
Whats a stratovolcano
A stratovolcano, is a tall and steep-sided volcano formed by alternating layers of lava, ash, and volcanic debris. They are characterized by explosive eruptions and can have a conical shape. Stratovolcanoes are known for their potential to produce pyroclastic flows, lahars, and ashfall. They are often found in subduction zones where tectonic plates collide.
Whats a cinder cone volcano
A cinder cone volcano is a type of volcano that is small in size It is formed by explosive eruptions that eject fragments of lava, ash, and volcanic gases into the air. These fragments, known as cinders or scoria, fall back to the ground and accumulate around the vent, building up the cone-shaped structure. Cinder cone volcanoes are typically short-lived.
Whats a dome volcano?
It is formed by the slow extrusion of highly viscous(sticky)lava, which piles up and solidifies around the vent. Dome volcanoes are often associated with explosive eruptions and can be found in volcanic areas where the lava is too thick to flow far from the vent.
Are cone and strato the same
Yes
What are the three types of magma
Basaltic, andestic, and rhyolitic
How are andestic and rhyolitic magma sourced
Subduction
What is the source of basaltic magma
Stretching of the crust or from a hot spot in the mantle
Whats the level of silica in basaltic magma
Low
Whats the level of silica in andestic magma
Medium
Whats the level of silica in rhyolitic magma
High
What does viscousity mean
it describes the resistance of lava to flow. Lava with high viscosity is thick and doesnβt flow easily, while lava with low viscosity is more fluid and flows more easily.
Whats the viscosity of basaltic magma
Runny (moves fast)
Whats the viscosity of andestic magma
Sticky (average speed)
Whats the viscosity of rhyolitic magma
Very sticky ( slow moving)
Amount of gas in basaltic magma
Small amount
Amount of gas in andestic magma
Larger - moderate/medium levels
Amount of gas in rhyolitic magma
Largest amount of all, violent
How does the amount of gas in magma affect a volcano
When there is a high concentration of gas in magma, it can lead to explosive eruptions. As the magma rises to the surface, the pressure decreases, causing the dissolved gases to rapidly expand and escape. This sudden release of gas can result in powerful explosions, ejecting ash, rocks, and lava into the air. On the other hand, magma with lower gas content tends to have more effusive eruptions, where the lava flows more smoothly and steadily.
Whats a lava flow?
A lava flow refers to the movement of molten rock, or lava, from a volcano. It occurs when the lava erupts from the volcano and travels down the slope, spreading out and covering the surrounding area. Lava flows can vary in speed and size.
Whats a pyroclastic flow?
A pyroclastic flow is a fast-moving mixture of hot gas, ash, and volcanic particles that cascades down the slopes of a volcano during an explosive eruption. It can reach speeds of hundreds of kilometers per hour and can be extremely destructive, incinerating everything in its path. Pyroclastic flows are known for their high temperature and density.
Whats a lahar?
A lahar is like a muddy avalanche that happens during or after a volcanic eruption. It occurs when volcanic ash, rocks, and debris mix with water, such as from heavy rainfall or melted snow, creating a fast-moving flow. Lahars can travel down the slopes of a volcano and through valleys, causing significant damage to structures and landscapes in their path.
What are the two types of volcanoes?
Hot spots and subduction. examples, TVZ= subduction, auckland area = hot spot
Whats a dormant volcano?
volcanoes that have not erupted in a long time but are expected to erupt again in the future.
Whats an extinct volcano?
those which have not erupted in human history
Active volcano
Likely to erupt again
