Earthquakes & Volcanos Flashcards
What is a volcano
A volcano is a conical hill or mountain formed by material from the mantle being forced through an opening or vent in the Earth’s crust.
What are active, dormant and extinct volcanoes?
Volcanoes are found in three states - extinct, dormant and active. An extinct volcano will never erupt again. A dormant volcano has not erupted in 2000 years. An active volcano has erupted recently and is likely to erupt again.
What are the different types of volcano?
Composite
Shield
Dome (Acid lava cones)
Composite volcanos
Composite volcanoes, sometimes known as strato volcanoes, are steep sided cones formed from layers of ash and [lava] flows. Composite volcanoes can rise over 8000 feet. Examples of composite volcanoes include Mount St Helens (USA). They are very explosive.
Shield volcanoes
Shield volcanoes have gently sloping sides and are formed from layers of lava. Eruptions are typically non-explosive. Shield volcanoes produce fast flowing fluid [lava] that can flow for many miles. Examples of shield volcanoes include the Hawaiian volcanoes. Although these eruptions destroy property, death or injury to humans rarely occurs.
Where are volcanoes located?
Volcanoes are found along destructive (subducting) plate boundaries, constructive (divergent) plate boundaries and at hot spots in the earth’s surface.
What is the Ring of Fire?
The ‘Ring of Fire’ is a volcanic chain surrounding the Pacific Ocean. It is formed along a destructive (subducting) plate boundary.
Earthquake
a sudden movement of the earth’s surface
Conservative Boundary
where two plates move alongside each other - although crust is neither created or destroyed here, earthquakes usually occur here.
Destructive Boundary (Convergent)
where two plates move towards each other - in the case of a plate consisting of continental crust meeting a plate consisting of oceanic crust, the oceanic crust will be subducted and destroyed as it is less dense.
Constructive Boundary (Divergent)
where two plates move away from each other resulting in new crust being formed.
Collision Boundary
where two plates of continental crust move towards each other creating fold mountains
What is a Plate Boundary?
The point where two or more plates meet is known as a plate boundary.
What are fold mountains?
Fold mountains are mountains formed from the folding of the earth’s crust.
foreshock
a small earthquake before a large one
joint
a crack in a rock
lava
molten rock at the Earth’s surface