volcano characteristics


A volcano is a vent from which the material from a magma chamber escapes. Volcanic eruptions can come from peaky volcanic cones, fractured domes, a vent in the ground, or many other types of structures.

creating magma

Volcanoes erupt because mantle rock melts. This is the first stage in creating a volcano. Remember from the chapter Materials of Earths Crust that mantle may melt if temperature rises, pressure lowers, or water is added. Be sure to think about how and why melting occurs in the settings where there is volcanism mentioned in the next few concepts.

where they are

Volcanoes are a vibrant manifestation of plate tectonics processes. Volcanoes are common along convergent and di- vergent plate boundaries. Volcanoes are also found within lithospheric plates away from plate boundaries. Wherever mantle is able to melt, volcanoes may be the result. What is the geological reason for the locations of all the volcanoes in the figure? Does it resemble the map of earthquake epicenters? Are all of the volcanoes located along plate boundaries? Why are the Hawaiian volcanoes located away from any plate boundaries? World map of active volcanoes (red dots).



Of all the volcanoes in the world, very few are erupting at any given time. Scientists question whether a volcano that is not erupting will ever erupt again and then describe it as active, dormant, or extinct. Active: currently erupting or showing signs of erupting soon. Dormant: no current activity, but has erupted recently. Extinct: no activity for some time; will probably not erupt again. Click image to the left or use the URL below. URL:


instructional diagrams

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how can a dormant volcano become active?

a) the magma chamber is empty.

-->  b) the magma chamber fills with magma.

c) a very large earthquake rocks the volcano.

d) none of these.

volcanoes are located around these type of boundaries.

-->  a) divergent and convergent

b) convergent and transform

c) transform and divergent

d) divergent, convergent and transform

a volcano on the hawaii hotspot is _; a volcano that has just moved off the hotspot is _; a volcano that is far from the hotspot is ____.

a) dormant; extinct; active

b) extinct; active; dormant

c) active; extinct; dormant

-->  d) active; dormant; extinct

magma is created when

a) the temperature rises

b) pressure lowers

c) water is added

-->  d) all of the above

these volcanoes are not currently erupting and will probably not erupt again.

a) active

b) dormant

-->  c) extinct

d) none of these

a dormant volcano may erupt again.

-->  a) true

b) false

only volcanoes that form a cone of some sort can erupt.

a) true

-->  b) false

a dormant volcano will become active at some point in the future.

a) true

-->  b) false

most active volcanoes are found in

-->  a) the pacific ring of fire

b) the alpine-himalaya belt

c) the east african rift

d) hawaii hotspot

what is the connection between the location of earthquakes and volcanoes?

a) where there are earthquakes there are always volcanoes.

-->  b) where there are volcanoes there are always earthquakes.

c) sometimes there are volcanoes but not earthquakes.

d) none of these.

diagram questions

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