Download Volcanoes

By: Sally Bruhn
Photo Curtsey of TheSchoolRun.com
 A volcano is an opening or a vent in the earth’s crust
that allows lava, hot gases, and ash to escape into the
atmosphere.
 Usually found at Hot Spots and along tectonic plates
(but not always).
 So, essentially, a volcano is an eruption of magma, hot
gases, and ash (among other things).
Keep in Mind
 There are 3 basic
categories of volcanoes
 Not all volcanoes erupt
with hot flowing lava,
like those of Hawaii.
 Not all volcanoes erupt
from top or side of a big
mountain either.
The 3Types of Volcanoes,
plus other characteristics
 Cinder Cone Volcanoes
 Composite Volcanoes (or
Stratovolcanoes)
 Shield Volcanoes
 Also discussed: Fissures,
Lava Domes, Calderas,
and Craters
 Relatively small compared to
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the other volcanoes (3m or
Bowl shaped crater at top of
984.21ft high)
mountain with steep sides
 Can form on their own,
Formed from a single vent in
however are usually
the Earth’s crust
associated with other
volcanoes, such as Composite
Violent eruptions
and Shield Volcanoes
Multiple eruptions of ash and
 Formed at vents sites of these
volcanic rock equals the
volcanoes
cinder cone shape
Sometimes, lava flows from  There are different types of
volcanic cones, due to the
base of cone
type of lava and rock that
erupt from them
Spatter Cone, Moon National Monument-Idaho
Diamond Head, Tuff Cone-Hawaii
Photograph by Bates Littlehales, National Geographic
Photograph by Peter T. White, National Geographic
Wizard Island, Middle of Crater Lake-Oregon
Photograph by Walter Meayers Edwards
Cinder cone Paricutin. Image credit: USGS
 Large, tall conical shaped
mountains, Several Meters
high
 Formed by repeated
eruptions, over time
 Many layers of different
kinds of lava flows
 This equals a composite of
layers such as lava, volcanic
ash, pumice, and tephra
 Lava, Pyroclastic material,
and Lahars flow from these
types of mountains
 Are some of the most
explosive, dangerous, and
famous Volcanoes
 Can be found on the
continental side of
subduction zones
 Does not erupt on a regular
basis or very often
Mount Fuji, Japan
Photograph by Melville B. Grosvenor, National Geographic
Mount St. Helens Eruption, May 18, 1980,
https://www.youtube.com/watch?v=Ec30
uU0G56U&spfreload=10
1980 Mount Saint Helens eruption, USGS
 Eruptions are usually
 Very large, broad mountain
 Looks like a shield from
above (hence the name)
 Formed by repeated
eruptions of very fluid lava
 If measured from actual
base, usually the highest
and largest volcanoes on
Earth-Even higher than Mt.
Everest
gentle compared to other
types of Volcanoes
 The lava flows slowly
compared to other
volcanoes
 Usually formed over a Hot
Spot, but not always
 Some Continental regions,
such as Washington State
and Oregon, have Shield
Volcanoes
Mauna Kea-Hawaii
Newberry-Central Oregon
Photo by Lee Siebert, 1995 (Smithsonian Institution)
Prestahnukur-Central Iceland
Photo by Paul Kimberly, 1994 (Smithsonian Institution)
Photo by Richie Williams, 1981 (U.S. Geological Survey)
Lava Dome
Characteristics
Fissure Characteristics
 Also known as Volcanic
 These are large fractures
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Domes
Created by lava that is too
thick (viscous) to flow very
far
Small masses of lava that,
over time, pile up and around
a vent
Grows because of the everexpanding lava from within
Can have a violent explosion
caused by intruding magma
 Are usually found at Hot
Spots and Divergent Plate
Boundaries, such as Hawaii
and Iceland
 When erupting, looks like a
line of lava or steam spewing
forth
 Old Fissures are known for
their Flood Basalts such as
the Columbia River Plateau
and Deccan Traps of India
Photograph by T.P. Miller, 1979
Lava Dome, Novarupta Vent-Katmai National Park and Reserve, Alaska
Hokkaido-Komagatake, Japan
Lava Dome-Ceboruco Volcano-Western Mexico
Photo by the Shin Engineering Consultant Company, 1996 (courtesy of
Mitsuhiro Yoshimoto, Hokkaido University)
Krafla Volcano-Iceland
Collapse of the Pu’u ‘O’o Crater
Floor,
https://www.youtube.com/watch
?v=TjLtt2yvJLs
Fissure Eruption Between
P’u’u’O’o and Napau Crater,
https://www.youtube.com/watch?v
=_0xsGIqn8WE
Photo by Lee Siebert, 1997 (Smithsonian Institution)
Photo by Michael Ryan, 1984 (U.S. Geological Survey)
Snow-Covered Calderas- Mona Loa, Hawaii
 Large volcanic craters
formed by two different
methods:
 First: formed by an
explosive volcanic
eruption
 Second: from a collapsed
magma chamber
Aniakchak Caldera, Alaska
Images: Courtesy of USGS
Photograph by Tyson Fisher, submitted to My Shot
 Crater Lake is actually a
Caldera, not a crater
 Was formed by a collapse
in the magma chamber
 After Mount Mazama
emptied its chamber via a
massive volcanic eruption
 Centuries of snow and rain
filled the caldera creating a
the deepest lake in the
United States and the
seventh deepest in the
World (1932ft/589m)
Caldera Demonstration Model by
USGS,
https://www.youtube.com/watch?v=
BBGmXsZHInw
Image Curtesy of USGS
Mount St. Helens-Washington State
 Is created by volcanic activity
 Some are deep with steep sides,
Erta Ale-Ethiopia
others are ide and shallow
 However, it is a bowl shaped
Photograph by James P. Blair, National Geographic
depression on the side (flank
craters) or near the top of
 At lower altitudes than
volcanoes (summit craters)
Summit Craters, Flank
 Summit Craters have volcanic
Craters are more dangerous
material at or near the Earth’s
surface, if calm enough
and destructive
scientists are able to get close
 Also created by magma
enough to study the lava
coming into contact with
groundwater creating a Maar
 These Maars are thin floored
lakes that are actually the
roofs of volcanic vents
Photo by Luigi Cantamessa, 1992 (courtesy of Pierre Vetsch)
Blair, J. (n.d.). [Photograph]. Retrieved from
http://education.nationalgeographic.com/education/encyclopedia/crater/?ar_a=1
Cantamessa, L. (1992). [Photograph]. Retrieved from http://www.volcano.si.edu/volcano.cfm?vn=221080
Edwards, W. (n.d.). [Photograph]. Retrieved from
http://education.nationalgeographic.com/education/encyclopedia/volcanic-cone/?ar_a=1
Fisher, T. (n.d.). [Photograph]. Retrieved from http://travel.nationalgeographic.com/travel/national-parks/crater-lakenational-park/
Kimberly, P. (1994). [Photograph]. Retrieved from http://www.volcano.si.edu/learn_galleries.cfm?p=2
Littlehales, B. (n.d.). [Photograph]. Retrieved from
http://education.nationalgeographic.com/education/encyclopedia/volcanic-cone/?ar_a=1
Miller, T. (1979). [Photograph]. Retrieved from http://volcanoes.usgs.gov/images/pglossary/LavaDome.php
Shin Engineering Company. (1996). [Photograph]. Retrieved from
http://www.volcano.si.edu/learn_galleries.cfm?p=5
Siebert, L. (1995). [Photograph]. Retrieved from http://www.volcano.si.edu/learn_galleries.cfm?p=2
Siebert, L. (1997). [Photograph]. Retrieved from http://www.volcano.si.edu/learn_galleries.cfm?p=7
TheSchoolRun. (2015). [Photograph]. Retrieved from http://www.theschoolrun.com/homework-help/volcanoes
United States Geological Survey. (1988). [Image]. Retrieved from http://geology.com/articles/caldera/
United States Geological Survey. (n.d.). [Photographs]. Retrieved from http://geology.com/articles/caldera/
United States Geological Survey. (1980). [Photograph]. Retrieved from http://www.kids-fun-science.com/compositevolcano.html
White, P. (n.d.). [Photograph]. Retrieved from
http://education.nationalgeographic.com/education/encyclopedia/volcanic-cone/?ar_a=1
Williams, R. (1981). [Photograph]. Retrieved from http://www.volcano.si.edu/learn_galleries.cfm?p=2
YouTube. (2010). Caldera Demonstration Model. Retrieved from https://www.youtube.com/watch?v=BBGmXsZHInw
YouTube. (2011).Collapse of the Pu'u 'O 'o Crater Floor on March 5, 2011. Retrieved from
https://www.youtube.com/watch?v=TjLtt2yvJLs
YouTube. (2011). Fissure Eruption Between Pu’u’O’o and Napau Crater. Retrieved from
https://www.youtube.com/watch?v=_0xsGIqn8WE
YouTube. (2010). Mount St. Helens: May 18, 1980. Retrieved from
https://www.youtube.com/watch?v=Ec30uU0G56U