Science test volcanoes Flashcards

Terms Definitions
freely flowing lava
means "little stones" in Italian
What type of volcano is Hawaii?
a large, circular depression that forms when the magma chamber below a volcano partially empties and causes the ground above to sink
the place where magma rises through cracks in the earth's crust and comes from the magma chamber
lava plateaus
They form similarly to sheild volcanoes; built out of layers of runny, non-explosive lava. They aren't volcanoes.
The opening through which molten rock and gas leave a volcano
Composite volcano
Created by a combination of explosive and nonexplosive eruptions; broad base, steep at top.
Explain Pillow lava.
forms when lava erupts underwater. lava forms pillow shaped rounded lumps
The viscosity of magma depends upon its silica content and its
a) magnetism
b) temperature
c) pahoehoe
d) pyroclastic flow
b) temperature
Extinct Volcano
Havent erupted in recorded histor and probably wont
shield volcano
A wide, gently sloping mountain made of layers of lava and formed by quiet eruptions.
- the hot liquid that when rock partially or completly melts; may include mineral crystals
subduction zone
where 2 plates collide to form a volcano
TRUE OR FALSE: A caldera and a crater are formed similarly.
Volcanic Blocks
These are pices of solid rock that erupted from a volcano
What eruption causes a composite volcano?
Both Quiet and Explosive
Dormant volcanoes
these volcanoes have not erupted in a while, but could erupt again at any time
A volcano that may erupt again at some time in the future is
a) active
b) dormant
c) explosive
d) extinct
b) dormant
How a Composite Volcano Forms
sometimes, lava flows alternate with explosive eruptions of ash, cinder, and bombs creating a composite volcano
All of the following are examples of physical properties EXCEPT
a) melting point
b) hardness
c) ability to burn
d) density
c) ability to burn
What happens if the magma from underground moves quickly to the surface?
the pressure decreases and water and other compounds become gas
it traps gases and builds pressure in the magma chamber
Why does thick, sticky lava cause explosive eruptions?
What does the magma do in the mantle after it is formed?
It is less dense than the surrounding rock, so it floats up towards the surface like an air bubble.
A brittle stiff lava.
the inner layer of the earth
lava flows
Rivers of red hot lava.
Silica content
more=thicker, lighter, sticky, forms rhyolite(granite) when dry, pummus, obsidianless= thinner, darker, flows better, rock like basalt
An example of a cinder cone volcano.
cinder-cone volcano
steep, cone shaped volcano that usually has explosive eruptions
Volcanic ash
Can reach the upper atmosphere and circle the Earth for years
Magma sometimes forces its way out of the side of a volcano through a(n) VENT.
at tectonic plate boundaries
Where do most volcanoes form?
a partially or mostly burned piece of coal, wood, etc.
cinder cone volcano
A volcanic cone created entirely from pyroclastic material. They are small and explosive.
Central Valley
a huge basin with the Sierra Nevada and Coastal Ranges
Said of a volcano hat does not show signs of erupting in the near future
What are tectonic plate boundaries?
Areas where tectonic plates either collide, separate, or slide past each other.
A major volcanic belt known as the ____________________ circles the Pacific Ocean.
Ring of Fire
Solid volcanic debris
The name of the category of materials spewed out of a volcano during an eruption.
molten rock and metal
Describe what most of the Earth is made of.
Shield volcanoes have a ___ gas content and a ___ silica content. Explain
low, low- runny magma and quiet eruption
You live on a large volcanic island not far from an active volcano. Besides damage from lava, what other hazards might affect your town and it's people?
an eruption could cause landslides or avalanches of mud, melted snow or rock. If an explosive eruption occurs, clouds of hot burning gases could injure people. ash could bury the village, damage crops, and clog car engines.
fine, glassy fragments
made liquid by heat
Volcanoes occur along ________________.
plate boundaries
Extremely vesicular volcanic rock, usually rhyolitic in composition.
Island arc
String of volcanic islands
Fissure Eruptions
Fractures leaking lava or pyroclastics. Can be large or small, basaltic or rhyolitic.
A destructive process that have occurred previously at a volcano.
Large cracks in the earth's crust
Liquid magma that reaches Earth's surface
resistance of a liquid to flowing
quiet eruptions
Volcanoes that have very hot, low-silica magma generally erupt quietly (low-viscosity lava, called lava flow). Lava flows from a quiet eruption can travel for great distances. Quiet eruptions produce two different kinds of lava: pahoehoe and aa.
Cinder cones
Classic volcanic shape, created when pyroclasts build up after they are discharged from volcanic vents.
occurs when only steam reaches the surface. the temp. of the water abd steam are very hot and dangerous
sheets of igneous rock that run parallel to the layers they intrude. Horizontal - mafic lava.
What other plate boundaries are volcanoes found?
Hot spots
one the most famous volcanos in history
mountain created as liquid rock or ash erupts from inside the earth
The Moment Magnitude Scale
scale used most by scientists.
It comprises of the denser parts of the earth such as rock.
hot spot
A volcanic center located within a lithospheric plate that is thought to be caused by a plume of hot mantle material rising from depth.
Basaltic magma
Most common magma type, which is produced along midocean ridges and at hot spots within plates, as well as in continental rift valleys.
A fountain of water and steam that builds up pressure under the ground and erupts at regular intervals
black smoker
chimney vents on ocean floors. smoke is actually basalt really hot and 4-5 ft
role of heat
additional heat generated by friction and hot mantle rocks
T or F: Some types of volcanic activity do not involve the eruption of lava.
Volcanic Dust
Fine droplets of lava which harden when thrown high into the air.
quiet eruption
lava flows from vents, setting fire to, and then burying, everything in its path. Can cover large areas.
a funnel-shaped pit near the top of the central vent of a volcano
A mass of rock formed when a large body of magma cools inside the crust
A volcano that is no longer active and unlikely to erupt again
island chain
a formation of islands aligned above a volcanic hot spot
Explosive Eruption
an eruption that's lava is high in silica and viscosity
sedimentary rock
rocks that are made from bits and peices of other rocks
Pyroclastic material
Fragments of rock that form during a volcanic eruption
Composite Volcanoes
are formed from lava and cinders to make a high mountain, can have violent eruptions
Large igneous provinces (LIP)
A large volume of predominantly mafic extrusive and intrusive igneous rock whose origin lies in processes other than normal seafloor spreading.
T or F: Silica is rarely found in the crust.
magma chamber
the body of molten rock that feeds a volcano
What are the major island arcs?
Japan, New Zealand, Indonesia, the Caribbean islands, the Philippines, and the Aleutians
On what divergent plate boundaries are volcanoes found?
Mid ocean ridges & continental rift
Why is silica content important when studying magma?
It helps determine the viscosity - the higher silica the higher viscosity and vice versa
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