EPSC 185 Lecture Notes - Lecture 10: Mount Aniakchak, Krakatoa, Subduction

26 views3 pages
Volcanism:
-Molten magma rises within the earth and is erupted either quietly (lavas) or violently
(pyroclastic)
3 types of volcanoes:
Active - doesn't need to erupt. Any sign for example gas coming out of the volcano, hot rocks
inside means it is an active volcano.
Instinct - suppose to be dead means all the lava and the rocks are solidified into igneous rocks
and it is instinct.
Dormant - a volcano that scientists remove from the active list of volcanoes but they have a gut
feeling that it will erupt one day. It is considered asleep but it can erupt at any moment without
warning.
Shield volcano (red - because of the lava) and Stratovolcano (grey)
Terminology:
Magma - molten rock sometimes containing suspended minerals and dissolved gasses. Magma
forms when temperatures rise sufficiently high for melting to occur in the earth’s crust or mantle.
Volcano - a vent at the surface in which magma, solid rock, and gases erupt.
Lava - magma that reaches the surface and pours out over the landscape
Controls:
-Two controls on explosivity are:
1) The silica content and
2) The gas content of the magma
*3 main types of magmas within the earth:
-Basalt (the melting of the mantle and the ocean crust): 50% SiO2, gas-poor
-Andesite (subjective zones): 60% SiO2, gas-rich
-Rhyolite + granite (granite solidifies underground. When it gets to the surface it becomes lava
which is rhyolite. They are rich in silica which means they belong to the continental crust): 70%
SiO2, gas-rich
Magmas with higher silica contents are more viscous
Viscosity:
-A substance resistant to flow
-**Dependent on temperature and composition
Magma viscosity and volcanic behaviour:
A- hotter lavas (basalt) are less viscous than cooler lavas and travel long distances
B- tends to break up as it flows (andesite)
C- lava (rhyolite) piles up as a dome
Five major types of volcanoes:
Caldera - a large depression created by the collapse of a volcano (strongest volcano)
Cinder cone - a simple volcano built from blobs of lava ejected from a single vent
Shield volcano - built from countless outpourings of fluid lava flows
Stratovolcano - built of layers of lava, ash, and volcanic debris
Lava dome- mound formed when viscous lava piles up around vent
Volcano types: shield volcanoes (basaltic, more gentle)
-Shield volcanoes are broad, gently sloping volcanoes
-They are composed mainly of basaltic lava flows
-This is a view of Muana, Loa, Hawaii, from the cinder cones of Muana Kea
-Muana Loa is the tallest volcano on earth, as measured from the sea floor
Shield volcanoes on Mars:
-Other planets also have shield volcanoes
-This is the largest shield volcano in the solar system, Olympus Mons on mars
find more resources at oneclass.com
find more resources at oneclass.com
Unlock document

This preview shows page 1 of the document.
Unlock all 3 pages and 3 million more documents.

Already have an account? Log in

Document Summary

Molten magma rises within the earth and is erupted either quietly (lavas) or violently (pyroclastic) Any sign for example gas coming out of the volcano, hot rocks inside means it is an active volcano. Instinct - suppose to be dead means all the lava and the rocks are solidi ed into igneous rocks and it is instinct. Dormant - a volcano that scientists remove from the active list of volcanoes but they have a gut feeling that it will erupt one day. It is considered asleep but it can erupt at any moment without warning. Shield volcano (red - because of the lava) and stratovolcano (grey) Magma - molten rock sometimes containing suspended minerals and dissolved gasses. Magma forms when temperatures rise suf ciently high for melting to occur in the earth"s crust or mantle. Volcano - a vent at the surface in which magma, solid rock, and gases erupt.

Get access

Grade+20% off
$8 USD/m$10 USD/m
Billed $96 USD annually
Grade+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
40 Verified Answers
Class+
$8 USD/m
Billed $96 USD annually
Class+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
30 Verified Answers

Related Documents