Volcanoes
Hot Spots- area of high temp. lava
- made Hawaii
View From Space - Klyuchevskaya, Russia
Magma – molten rock beneath
the surface
Lava – molten rock on the
surface
Types of Volcanoes
Composite Cone
or
It’s a composite volcano.
It’s made up of different layers of
lava and ash.
A Cinder
Cone:
Wizard
Island at
Crater Lake,
Oregon
Icelandic Volcanoes
Eyjafjallajokull
Tuff Ring: Diamond Head, Hawaii
Shield Volcano: Mauna Loa, Hawaii
Stratovolcano or Composite
Cone: Mount Shasta, California
Shastina and Landslide Deposit
Products of Eruptions
Lava Flows
• Pyroclastic
Debris
• Bombs
• Lapilli
• Ash
• Mudflows
• Landslides
Gases
• Steam
• Carbon Dioxide
• H 2S
• SO2
• HCl
• HF
Environmental Hazards of
Volcanoes
Pollution
• SO2, HCl in Water
Lava Flows
Falling Ejecta
Ash Falls
• Building Collapse
• Crop Destruction
Mudflows
• Direct Damage (Colombia,
1985)
• Floods (Several Types)
Blast (Mt. St. Helens, 1980)
Pyroclastic Flow (St. Pierre,
1902)
Gas (Lake Nyos, Cameroon,
1986)
Pyroclastic Flow or NueeArdente (French: Fiery Cloud)
How Calderas Form:
Crater Lake, Oregon
Colorado Volcanoes ?– La Garita
Evolution of Volcanoes
An active volcanic landscape
Evolution of Volcanoes
A volcanic landscape after a million years or so
Mount Hood is a stratovolcano in
the Cascades of northern Oregon
The caldera at Crater Lake National Park cuts
through the flanks of the former Mount
Mazama (composite cone)
Layers of tephra on Usu (stratovolcano) in Japan.
The crater by the volcanologists was formed in
1977-1978.
Eruption of Galunggung (stratovolcano) in
Indonesia.
1980 eruption of Mt. Saint Helens produced 0.1
cubic miles (0.5 cubic km) of ash.
Stratovolcanoes are
associated with
subduction zones, areas
where dense oceanic
plates are pushed
beneath more buoyant
continental plates.
The cinder cone in the above photo is Puu
Lilinue on Mauna Kea in Hawaii.
Cinder cones are produced by "fire fountains,"
low-energy eruptions that propel fragments of
lava 100s of feet into the air.
A volcanic dome is a steep-sided, rounded extrusion of highly
viscous lava squeezed out from a volcano to form a domeshaped, or bulbous, mass of lava above and around the
volcanic vent
During the 1989-1990 eruption of Redpubt
volcano (Alaska) several lava domes grew
and collapsed near the summit of the volcano.
Flood Basalts
• The Columbia River
basalts cover parts of
the states of Oregon,
Washington, and Idaho
and are a famous
example of flood
basalts that produced a
lava plain.
Lava
• Eruptions under water or
ice produce pillow lava
(become pillow basalt)
Coastal Flows
"Pahoehoe" and "aa" are Hawaiian words used
to describe the type of lava volcanoes have
Aa Flow
Pahoehoe
Lava Tubes