10-1) Volcanoes and Plate Tectonics Flashcards
(17 cards)
what is a volcano?
a weak spot in the crust where magma from mantle rises to the surface.
what is the largest volcano in europe? largest volcano of the century?
Mount Etna and Mount Pinatubo.
what is magma?
a mixture of partially melted mineral crystals, dissolved gases, and water
where and how is magma formed?
forms in crust and upper mantle when solid rock partially melts
what does magma depend on?
heat, pressure, and water content
describe how magma depends on heat
near solid rock is near its melting point. mantle heats subduction slabs.
describe how magma depends on pressure
the deeper into Earth’s interior, pressure rises, decompression melting
what is decompression melting?
when rock rises and melts due to reduced pressure. rock melting point decreases as pressure drops.
describe how magma depends on water content
increasing water content of rock lowers rock’s melting point.
Wet rock beneath surface melts at a much lower temperature than dry rock of the same composition and pressure
a volcano forms a what?
a mountain when layers of lava and volcanic ash erupt.
where do volcanoes often occur?
where plates are moving apart, together, or at hot spots
describe divergent boundary volcanism
plates apart; mantle rock rises to fill in the gap and decompression melting occurs. magma erupts through center and form rifts. (long deep cracks)
describe the first type of convergent boundary volcanism when plates move together
- oceanic plate collides with another ocean plate one goes under the other. magma form volcanoes and sometimes a volcanic island arc.
describe the second type of convergent boundary volcanism
- oceanic plates slide under continental plates. rock is deep and magma forces its way up forming volcanoes. sometimes forming continental volcanic arc.
where does intraplate volcanism occur?
occurs within a plate
what is a mantle plume?
area where the mantle is unusually hot, hot rock forced upward toward the crust. volcanoes form, sometimes rise above sea level and form islands.
what is a hot spot?
a volcanic region that results from mantle plumes
