Features of a Volcano
Volcano Vocab and Features
Types of Volcanoes I
Types of Volcanoes II
More volcanic features and
Volcanic Hazards
100
A ______ is an opening in the surface of the Earth from which magma (molten subsurface rock ) and associated gases and ash erupt; also, the form or structure, sometimes conical, that is produced by the ejected material.
volcano
100
The viscosity of magma depends on temperature, incorporated gases, and most importantly ____ content
What is silica content
100
How are volcanos classified?
By the types of eruptions they produce
100
Magma high in silica is (more/less) viscous than lavas low in silica.
more Think high viscosity is like honey, and low viscousity is like water.
100
How does a dike differ from a volcanic neck?
A dike is a linear feature while a neck is cylindrical.
200
The _____ _______ is a huge, subterranean caldron of molten rock that is less dense than the surrounding rock and rises buoyantly, sometimes under great pressure to the surface.
What is magma chamber
200
Volcanic eruptions, especially explosive eruptions, eject fragments of volcanic rocks and lava collectively called ____.
What is tephra
200
Eruptions can be 1 of 2 types, what are they?
Effusive eruptions or explosive eruptions
200
What two types of volcanos produce explosive eruptions?
Cinder cones and composite
200
What kind of landscape feature is associated with flood basalts?
Lava plateau.
300
The main conduit through which magma moves toward the surface is the ____ ____.
central vent
300
Ground-hugging _____ flows of fast-moving gas and fragments of rock having temperatures of 500 oC can rush down the flanks of a volcano at speeds reaching 100 km/hr, carbonizing all in their path.
pyroclastic
300
Effusive eruptions are those that create vast lava flows of low viscosity, fluid lava. Knowing this, would the magma have high or low silica content?
Magma associated with effusive-type eruptions is relatively low in silica and thus "easily" flows up the vent and spreads across the surface.
300
What type of volcanos are primarily composed of layers of pyroclastic material built from rock fragments once lodged in the central vent of the volcano
Cinder cones
300
Mudflows created when hot pyroclastic material and ash rains down and melting snowpacks.
lahar
400
____ ____ are found on the sides of some volcanoes where lava is extruded.
Lateral Vents
400
___ ____ are places where a chamber of magma has accumulated at depth beneath the surface
Hot spots
400
Effusive eruption lave flows can take two different forms. _______ (a Hawaiian term) lava has a glistening, ropy like appearance as it moves and cools. or ___ lava is more pasty than pahoehoe and forms a sharp, clinkery, rough surface. As the core of the flow moves across the surface, the rough "clinkers" are carried along the top of the flow. At the leading edge of the flow, the clinkers tumble forward into a heap.
Pahoehoe or AA
400
______, or stratovolcanoes form from alternating eruptions dominated by pyroclastics or lava and display layers of these alternating flows. These volcanoes are among the tallest on earth.
Composite
400
What other geologic hazard accompanies volcanic eruptions?
Earthquakes
500
An extremely large crater is some times found at the summit of a volcano. These massive craters called _____, are created when pressure builds inside the volcano until the top is literally blown off, magma drains back into the central vent and the top of the cone collapses in.
calderas
500
List locations where volcanic activity tends to be concentrated in. (three)
Along the mid-ocean ridge. Plate boundaries, especially subduction zones. Mantle plumes ("hot spots")
500
The Hawaiian Islands are an example of what type of volcano?
shield volcanoes
500
Shiprock, New Mexico and Devils Tower are examples of what?
Volcanic necks
500
What are glowing avalanche clouds?
Clouds of noxious gases and fiery ash that rapidly move down mountain slopes.
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