Volcanoes 14.1

Question 1

Volcanism

Answer 1

describes all the processes associated with the discharge of magma, hot fluids, and gases.

Question 2

What percentage of magma erupts from plate boundries?

Answer 2

5%

Question 3

Convergent volcanism

Answer 3

-tectonic plates collide at convergent plate boundaries.
- Subduction zones form where oceanic crust descends into the mantle.
-the subducted crust melts and forms magma.
-magma rises to the surface forming volcanic mountains on land or volcanic islands in the ocean
-explosive eruptions

Question 4

Two major belts

Answer 4

Circum-Pacific Belt & Mediterranean Belt

Question 5

Divergent Volcanism

Answer 5

-tectonic plates move apart at a divergent plate boundaries.
-At mid-ocean ridges, magma rises to fill in the gap between the plates
-2/3 of Earths volcanism occurs underwater along divergent boundaries at ocean ridges
-non-explosive eruptions & pillow lava occurs

Question 6

Hot spot

Answer 6

unusually hot area in Earth’s mantle where high-temperature plumes of magma rise toward the surface.

Question 7

Hot spots (more in depth)

Answer 7

-most hot spots occur where columns of solid, hot material from deep mantle, called mantle plumes, rise and reach the crust.
-when a mantle plume reaches the crust, the plume spreads out.

Question 8

Flood basalt

Answer 8

huge amounts of lava that erupt from fissures.
these eruptions can form flat planes called plateaus (takes hundreds or thousands of years)

Question 9

Fissure

Answer 9

a long crack in the earths crust

Question 10

Conduit

Answer 10

A tube-like structure that allows lava to reach the surface

Question 11

Vent

Answer 11

opening in Earths crust through which lava erupts and flows out onto the surface

Question 12

Crater

Answer 12

bowl-shaped depression that forms around the central vent at the summit of a volcano

Question 13

Caldera

Answer 13

larger crater that can form when the summit or side of a volcano collapses into the magma chamber during or after an eruption.

Question 14

Sheild volcanoes

Answer 14

definiton: broad volcano with gently sloping sides
- largest of the tree types of volcanoes
-quiet eruptions
-composed of layers of solidified basaltic lava

Question 15

Cinder Cone volcanoes

Answer 15

definition: steep-sided, generally small voncano that is built by the accumulation of tephra around the vent.
-smallest of the three volcanoes
-cone shaped
- explosive eruptions
-composed of fragments of basaltic lava

Question 16

Composite volcanoes

Answer 16

definition: generally cone-shaped with concave slopes
- larger than cinder cone volcanoes
-Tall, majestic mountains
- composed of layers of rock from explosive and quiet lava flows
-cycles through periods of quiet and explosvie eruptions