Volcanic Eruptions

Question 1

Volcanoes are mostly found along

Answer 1

Convergent boundaries

Question 2

three types of magma

Answer 2

basaltic, andesitic, rhyolitic

Question 3

is the process where the early-formed minerals are denser (heavier) than the liquid (melt) and sink toward the magma chamber

Answer 3

Crystal Settling

Question 4

occurs during the ascent of two chemically distinct magma bodies as the more buoyant mass overtakes the more slowly rising body

Answer 4

Magma mixing

Question 5

Most magma that erupts on the Earth’s surface is __________ in
composition and has a temperature of ______________°C to __________°C.

Answer 5

basaltic, 1000°C to 1250°C

Question 6

partial melting of the ultramafic rock __________ will yield a magma of basaltic composition.

Answer 6

peridotite

Question 7

Basaltic magmas are generated at

Answer 7

subduction zones

Question 8

are steep-sided mounds that were formed from viscous lava (rhyolitic lava); lava domes can act like a plug when it begins to solidify and thus allow pressure to build in the magma chamber and result in a more explosive eruption

Answer 8

lava dome

Question 9

formed when lava eventually cools and solidifies into an igneous rock body

Answer 9

lava flow

Question 10

formed when large volumes of basaltic lava will flow onto the surface along large fracture zones

Answer 10

Continental flood basalt

Question 11

an accumulation of extrusive materials around a vent (sometimes a fault or fracture) through which lava, gas, or pyroclastics are ejected.

Answer 11

volcano

Question 12

relatively small and is formed when lava is ejected into the air and cools into pyroclastic material called cinders, which then fall and accumulate around the vent

Answer 12

cinder cone volcano

Question 13

also known as “stratovolcano”; are cone-shaped volcanoes with steep slopes consisting of alternating layers of pyroclastic material and lava flows

Answer 13

Composite cone volcano

Question 14

a circular depression where lava and pyroclastic material is being ejected

Answer 14

crater

Question 15

are exceptionally large landforms composed primarily of basaltic lava flows. It has a broad cross-sectional shape due to the low viscosity of basalt which can travel considerable distances from the vent and spread out over large areas

Answer 15

shield volcano

Question 16

a circular depression that forms after an eruption when large volumes of magma are ejected from a shallow magma chamber, leaving it relatively empty and thus causing it to subside/collapse.

Answer 16

caldera

Question 17

three classifications of volcanoes

Answer 17

Active Volcanoes
Potentially Active Volcanoes
Inactive Volcanoes

Question 18

The ____________ caused by the overlying rocks gives the molten material within the magma chamber a tremendous amount of fluid pressure.

Answer 18

confining pressure

Question 19

a zone of molten material where magma accumulates and occurs at a considerable depth.

Answer 19

magma chamber

Question 20

As magma rises and encounters less confining pressure, it expands and pushes outwards on the surrounding rocks, thereby creating ________ and ________ and subsequent earthquakes.

Answer 20

fractures and faults

Question 21

If the overlying rocks at some point are no longer capable of containing the fluid pressure, then significant amounts of magma can make its way to the surface, resulting in a __________________

Answer 21

volcanic eruption

Question 22

Eruptions create pulverized rock that is ejected along with the lava
which is collectively known as

Answer 22

pyroclastic materials

Question 23

The finest material, called __________, can travel hundreds, even
thousands, of miles before falling back to Earth’s surface.

Answer 23

volcanic ash

Question 23

solidified lava and pulverized rock

Answer 23

Tephra

Question 24

ways to classify pyroclastic deposits and rocks

Answer 24

1. Grain Size
2. Grain Size Mixture
3. Components

Question 25

It is a relative measure of the explosiveness of volcanic eruptions, and was devised by Chris Newhall of the United States Geological Survey and Stephen Self at the University of Hawaii in 1982.

Answer 25

Volcanic Explosivity Index (VEI)

Question 26

most common hazard on an explosive volcanic eruption

Answer 26

pyroclastic material and hot gases

Question 27

also called as debris avalanche, occurs whenever steep flanks of a volcano become unstable and results rapid downslope movement
of rocks, debris, and/or snow/ice.

Answer 27

Volcanic landslide

Question 28

also called a lahar or debris flow, is a mixture of ash, rock, and
considerable amounts of liquid water.

Answer 28

Volcanic mudflow

Question 29

volcanic gas is mainly composed of

Answer 29

water vapor (H2O)
carbon dioxide (CO2)
sulfur dioxide (SO2)