Volcanos Flashcards

Terms Definitions
to adorn
stude of volcanoes
Gas and Viscosity determines
das Geschoss
the missile/the bullet
Pyroclastic flow
Dust, ash rocks 100+mph.
a liquid's resistance to flowing
intermediate; contains more silica than basalt and erupts explosively
cuts across existing structures; not in agreement
mud flows of superheated, liquified snow and mud slides
what determines the viscosity?
amount of silica
common on plate OF earths crust
Controlling Factors
Magma viscosity-Resistance to flow, gases cant escape, Big explosionTemperatureDissolved Gas
Formation of Volcanoes
Mantle rock melts, forming magma
Mantle forces its way upward through the crust
􀂃 Under pressure
􀂃 Contains carbon dioxide, sulfur dioxide, and water vapor
􀂃 As magma approaches surface, pressure decreases, causing gases to expand rapidly
o Magma erupts at the surface as a volcano
the second largest particle that is blown into the air by a volcanic eruption; it is a small rough bomb that is no more than a couple of centimeters across
Molten rock that has extruded onto Earth's surface
Shield Volcano
Wide gently-sloping volcano built up by quiet eruptions of low viscosity lava
A mountian that formes in earths crust.
types of volcanoes
cinder cone, broad profile, composite
Volcanic neck
The main vent of a volcano
Magma that forces across rock layers hardens into a
Nuee Ardente
french word for pyroclastic flow means glowing cloud
Pillow lava
lava that solidifies in an underwater environment and develops a structure that resembles a pile of pillows.
use a diagram like figure 8, to explain how the Hawaiian islands formed
A fountain of water and steam that builds up pressure underground and erupts at regular intervals.
a long tube through which magma moves from the magma chamber to Earth's surface.
the heating of underground water by magma
geothermal activity
a hot, fast-moving type of lava that hardens to form smooth, ropelike coils.
Mount St. Helen's
composite and it erupted in 1980
type of pyrolastic depris its near the vent
cinder cone volcano
a steep, cone-shaped hill or small mountain made of volcanic ash, cinders, and pumice
Hawaiian Islands
Island chains that are the result of hot spot activity in the middle of a plate; hot spot does not change location as the plate moves
45 degrees
On average how much does a subducting plate dip?
a string of islands formed by the volcanoes along a deep-ocean trench
island arc
Converging Boundaries
A boundary that forms by the collision of 2 lithospheric plates.
a mass of rock formed when a large body of magma cools inside the crust
island arc
A string of islands formed by the volcanoes along a deep ocean trench.
Ring of Fire
a major belt of volcanoes that rims the Pacific Ocean
Examples of diverging plate volcanoes
Mid Ocean Ridges and Rift Valleys
When do explosive eruptions occur?
when magma is high in silica
Pacific Ring of Fire
the ring of volcanoes that circle the Pacific Ocean from the tip of South America, along the west of the U.S., through Alaska and the Kamchatka Peninusula , down through Japan, Indonesia, and the islands in the South Pacific.
fumarole, p 147
a vent in a volcanic area from which fumes and gasses escape
What does a volcanic neck look like?
a giant tooth stuck in the ground
unlikely to erupt again
Plate boundaries
Where volcanoes most likely form
not erupting in long time
erupts violently
Cool, stiff lava that forms jumpled heaps of sharp chunks near the vent. Slow-moving, doesn't travel far.
Forms when a magma chamber empties, and the ground above it falls in, creating a large, sinking depression.
Volcanoes that form along a mid-ocean ridge occur at a(n) DIVERGING PLATE BOUNDARY.
- lava flows, like wax dripping forming a glassy surface with rounded wrinkles
- this lava gets its name from the Hawaiian word "ropy" because it's surface resembles coils of rope
Describe composite volcanoes.
erupt explosively and non explosively, steep sides
TRUE OR FALSE: The less water, the larger the explosion.
magma chamber
the pocket beneath a volcano where magma collects
What is the other African volcano that, along with Mt. Kenya, is one of the oldest volcanoes?
Mt. Kilimanjaro
Explain Blocky lava.
cool, stiff. doesn't travel far from the erupting vent. oozes from volcano and forms jumbled piles of sharp chunks
Several kilometers from a volcano, a geologist observes an old lava flow made up of dark-colored basalt rock. The geologist infers that the lava must have had
a) medium viscosity
b) high viscosity
c) low viscosity
d) high silica content
c) low viscosity
an opening at the surface of the Earth through which volcanic material passes
Said of a volcano that is erupting or has shown signs of erupting in the near future
How is lava classified?
by its viscosity and the surface texture of lava flows
Volcanic Bombs
Big blobs of magma, that harden in the air
Explain water and magma underground
because magma is underground, it goes through intense heat and pressure and water stays dissolved in the magma.
What are the other landforms made from volcanic activity?
craters, calderas, and lava plateaus
indicators that a volcano is about to erupt
bulges on sides,falling rock, steam ,increase in sulphur dioxide
Explain Volcanic Bombs. And how is the shape formed?
large blobs of magma that harden in the air. Shape was caused my magma spinning through the air as it cooled
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