Three different types of volcanoes exist; Volcano An opening in Earth’s crust through which...
-
Upload
matthew-perkins -
Category
Documents
-
view
220 -
download
0
Transcript of Three different types of volcanoes exist; Volcano An opening in Earth’s crust through which...
Three different types of volcanoes exist;
Volcano
An opening in Earth’s crust through which igneous matter (lava, ash, cinder, and gases) are erupted.
Reference:
Pages: 95 - 101
VolcanoesVolcanoes
a. Composite conesa. Composite cones
b. Shield volcanoes b. Shield volcanoes
c. Cinder conesc. Cinder cones
broad slightly domed basaltic lava
ejected pyroclastic stuff steeply angled sides relatively small
large, symmetrical alternating lava flows & pyroclastic deposits
VolcanoesVolcanoes
A) Composite or StratovolcanoLarge, nearly symmetrical structure formed from alternating lava flows and pyroclastic debris.
These volcanoes are produced by very viscous (thick) lavas mainly andesitic in composition.
Display the most violent type of volcanic activity. Erupting lava and pyroclastic material.
Form a steep sided and relatively narrow base volcano (up to 20 km wide) compared to shield.
Most active composite cones are in a narrow zone that encircles the Pacific (Pacific Ring of fire).
VolcanoesVolcanoes
A composite volcano
These volcanoes are found in mountainous environments where oceanic – continental convergence occurs. Ex. Andes Mountains.
Examples of these volcanoes include; Mount Mayon in the Phillipines, Mount Fuji in Japan, and Mount St. Helens In the USA.
VolcanoesVolcanoes
A) Composite or Stratovolcano
Mt. Fuji, Japan
Mt. Mayon, Philippines
large, symmetrical alternating lava flows & pyroclastic deposits
large, symmetrical alternating lava flows & pyroclastic deposits
VolcanoesVolcanoes
Cascade volcanic range: NW US
•Result of past/present subduction of oceanic crust
•Many volcanoes still active
Mt. St. Helens
9500’
8150’(1350’ shorter!)
Mt. St. Helens
Ejected nearly a cubic kilometer of ash & rock debris
59 deaths
ash blown over 11 miles high!
Mt. St. Helens – a typical composite volcano
Mt. St. Helens following the 1980 eruption
B) Sheild VolcanoBroad, slightly domed structure formed from fluid lava flows.
These volcanoes are produced by lavas that display a low viscosity and are mainly basaltic in composition.
Form relatively wide base volcanoes compared to its height and are the largest of the three types of volcanoes.
VolcanoesVolcanoes
These volcanoes are mainly found on the ocean floor along divergent boundaries and hot spots.
Examples of these volcanoes include; Hawaiian Islands (Mauna Loa and Kilauea), Midway Islands.
VolcanoesVolcanoes
B) Sheild Volcano
HawaiiHawaii
VolcanoesVolcanoes
MidWayMidWay
T&L Fig 4.C
Hawaiian Islands
Key terms: magma chambermagma chamber
vent/pipevent/pipe
calderacaldera
flank eruptionflank eruption
VolcanoesVolcanoes
C) Ash and Cinder Volcano
Built mainly of ejected pyroclastic materials, such as, ash and cinder.
Volcanic cone has a very steep slope that is usually less than 300 meters high.
Form on the base of larger volcanoes and are the smallest of the three types of volcanoes.
Example: Paricutin in Mexico.
VolcanoesVolcanoes
Sunset Crater – a cinder cone near Flagstaff, Arizona
1000 feet tall
(900 years old)
Comparison of Volcano TypesComposite volcanoes are the second largest ranging in size from
10’s of kilometers wide and up to 3 km high.
are the largest reaching up to 100’s of kilometers wide and up to 4 km above sea level.
Shield volcanoes
are the smallest approximately 1 – 2 km wide and up to 300 meters (1000 ft) high.
Cinder volcanoes
Relative Sizes
5km
5km
Shield Volcano
Composite Volcano
Cinder Volcano
VolcanoesVolcanoes
A size comparison of the three types of volcanoes
VolcanoesVolcanoes
Volcano Type Characteristics