Transcript volcano_powerpoint_semi_final[1]

• They are the most common type of volcanoes.
• Many cinder cones have a bowl-shaped crater at the summit.
• They are commonly found on the flanks of shield volcanoes, strato
volcanoes, and calderas.
• Geologists have identified nearly 100 cinder cones on the flanks of Mauna
Kea, a shield volcano located on the island of Hawaii.
• They are smaller and simpler than composite volcanoes.
• It forms when ash, cinders and bombs pile up around the vent to form a
circular or oval cone.
• “Cinders are melted volcanic rock that cooled and formed pebble-sized
pieces when it was thrown out into the air.”
• “They are ejected from a single vent and
accumulate around the vent when they fall back
to earth.”
• “Cinder cones can occur alone or in small to
large groups or fields.”
• “Most have a bowl-shaped crater at the
summit.”
• “The longer the eruption, the higher the cone.”
• The shape of a cinder cone can be modified
during its (short) life.
• “Cinder cones are built from lava fragments
called cinders. The lava fragments are ejected
from a single vent and accumulate around the
vent when they fall back to earth.”
“A cinder cone or scoria cone is a steep conical hill of
volcanic fragments that accumulate around and
downwind from a volcanic vent. The rock fragments,
often called cinders or scoria, are glassy and contain
numerous gas bubbles "frozen" into place as magma
exploded into the air and then cooled quickly. Cinder
cones range in size from tens to hundreds of meters tall.
Cinder cones are made of pyroclastic material.”
•
•
•
•
Also called strato volcanoes
Formed by alternating layers of lava and rock fragments
Often have snow capped peaks
Between eruptions, they seem extinct because they are very
quiet
• Eruption is explosive
• Caused by viscous magma
• When the magma rises, it clogs the opening. This results in
gas building up until it explodes
• Can grow about 8,000 ft above bases
• Can grow very large but the sides weaken too much that
the volcano collapses because of gravity
• Many located on the “Ring of Fire”
• Volcanoes form when an oceanic plate boundary and a
continental plate boundary meet. The oceanic goes
under the continental because it is denser. This is called
subduction. Then hot magma rises and forms a volcano.
• They occur because the plates are moving. Underneath
the crust, convection is circling around causing the
plates to move and crash into each other.
• Shield volcanoes are big and made up of fluid lava flows.
• They get their name because the sloping hills that surround
them have a fan shaped pattern that looks like a shield.
• They have broad, sloping sides.
• Shield volcanoes are formed from the action of the gas or
steam or water vapor with heat from the earth’s core. This
melts rock turning it into magma. The pressure from the heat
of the gas pushes the magma up until it explodes. Molten
Magma shoots upward from under the ocean floor and breaks
through the plates and forms a shield volcano.
• Shield volcanoes could be made from hot spots under
the surface.
• Shield volcanoes are built up of effusive eruptions.
• Shield volcanoes measure to about 3-4 miles in
diameter.
• They measure up to 1,500-2,000 feet high.
Diagram of a Hawaiian eruption
(key: 1. Ash plume 2. Lava fountain 3. Crater 4. Lava
lake 5. Fumaroles 6. Lava flow 7. Layers
of lava and ash 8. Stratum 9.Sill 10. Magma conduit
11. Magma chamber 12.Dike) Click for larger version
• When a volcano explodes, houses,
buildings, roads, and fields can get
covered with ash. People will often
evacuate their houses. If the ash is really
heavy, it can make it hard, or impossible,
to breathe.
• The most destructive volcano is Mt. Tambora in
Indonesia. It was an active composite volcano
that occurred on April 5th 1815. It killed 12,000
people directly from the volcano, and 80,000
killed from starvation afterward. That is a total of
92,000 people killed!
Composite Volcanoes
•
•
•
•
•
•
•
•
Mount St. Helens - Washington State
Mount Rainier - Washington State
Mount Vesuvius – Italy
Mayon Volcano - Luzon Island, Philippines
Mount Fuji – Japan
Mount Cotopaxi – Ecuador
Mount Shasta – California
Mount Hood – Oregon
Cinder Cone Volcanoes
•
•
•
•
•
•
•
•
•
•
Cinder Cones and Scoria Cones
California Cinder Cones
Cerro Negro, Nicaragua
Lava Butte, Oregon
Newberry Caldera Vicinity, Oregon
New Mexico Cinder Cones
Paricutin, Mexico
Portland Vicinity, Oregon
Sunset Crater, Arizona
Wizard Island, Crater Lake, Oregon
Shield Volcanoes
·Kilauea (Hawaii)
·Mauna Loa (Hawaii)
·Etna (Sicily)
·Piton de la Fournaise (Reunion)
·Erta Ale (Ethiopia)
·Fernandina and all Galapagos
volcanoes
·Nyamuragira (Congo)
·Karthala (Indian Ocean)
·Savai’i (Samoa)
·Aoba (Vanuatu)
•
•
•
•
•
•
•
•
•
•
•
•
•
http://library.thinkquest.org/17457/volcanoes/types.composite.php
http://www.weatherwizkids.com/weather-volcano.htm
http://www.k12.hi.us/~kapunaha/student_projects/volc_blowout/composite_volcano.htm
http://www.pdc.org/iweb/volcano_deadliest1.jsp
http://www.k12.hi.us/~kapunaha/student_projects/volc_blowout/cinder_cone_volcano.htm
http://en.wikipedia.org/wiki/Cinder_cone
http://library.thinkquest.org/17457/volcanoes/types.cinder.php
http://www.cotf.edu/ete/images/modules/volcanoes/typesc.GIF
http://geology.com/volcano/sp-crater.jpg
http://canarygeog.canaryzoo.com/Geog1/composite%20volcano.jpg
http://volcanoes.usgs.gov/Imgs/Jpg/Photoglossary/shieldvolcano1_large.jpg
http://library.thinkquest.org/06aug/00886/index_files/Page307.htm
http://vulcan.wr.usgs.gov/Glossary/CinderCone/description_cinder_cone.html