Restless earth- Volcanos Flashcards
How do volcanos form?
magma rises through weak points in the earths crust, the pressure of the magma finally erupts causing lava to spread. The lava cools and forms a new crust (rock). This process repeats to form mountain shapes
Where do volcanos occur?
Destructive and constructive plate boundaries
What is the magma chamber?
A collection of magma inside the earth, below the volcano
What is the main vent?
The main outlet for magma to escape
What are secondary vents?
Smaller outlets for which magma escapes
How is a crater created?
After the eruption blows the top off the volcano
How can volcanos activity be described?
Active
Dormant
Extinct
Characteristics of a shield volcano
Usually found at constructive plate boundaries
Low in height with gentle slopes
Form thin, running lava
Eruptions frequent but gentle
Characteristics of composite volcanos
Usually found at destructive plate boundaries
Made up of alternating layers of lava and ash
May have a very hot and fast moving pyroclastic flow (hot steam, ash, rock, and dust
A volcano case study?
An eruption in 1997 in soufriere hills volcano on the Caribbean Island of Montserrat (destructive plate margin)
What effects did the Montserrat eruption have?
Capital city (Plymouth) burnt under 12m of ash Two thirds of inhabitants leave the island
Soil more fertile
Tourist industry risen
What responses to the Montserrat volcano eruption took place?
People were evacuated
UK provide financial aid and redevelopment
An observatory built to predict future eruptions
Ways to monitor earthquakes
Thermal imaging and satellites to monitor heat
Gas samples and chemical sensors to detect sulphur
Features of a supervolcano?
At least 1000km3 of material
Erupts less frequently
Has a caldera (cone shape)
How many times has Yellowstone supervolcano erupted
3 in the last 3million years
