VOLCANOES EARTH SCIENCE Mrs. Baker cjcb2015
Jan 18, 2016
VOLCANOES
EARTH SCIENCE
Mrs. Bakercjcb2015
Volcanoes
• An opening in the Earth’s crust that erupts gases, ash, and lava (pyroclastic material).
There are more than 600 active volcanoes on Earth!
Mt. Kilauea in Hawaii is the most active volcano!
Vocabulary
Parts of a Volcano• A Magma Reservoir• B Flank• C Conduit• D Crater• E Solidified Lava• F Dike• G Ash• H Vent• I Sill
• INTERACTIVE WEBSITES (GO TO “LAUNCH”):• http
://www.pbslearningmedia.org/resource/ess05.sci.ess.earthsys.nyiragongo/anatomy-of-a-volcano/ (images)
• http://www.pbslearningmedia.org/resource/ess05.sci.ess.earthsys.volcanintro/volcanism/ (LOTS of information)
ViscosityMaterials that flow quickly have a
low viscosity. Examples: water, basaltic magma
The ability of a substance to resist flowing.
Materials that flow slowly have a high viscosity. Examples: syrup, Rhyolitic magma
Types of Magma
• Temperature, pressure, and amount of water affect the formation of magma.
Explosiveness of a Volcano
• The explosiveness of a volcano depends on the viscosity of the magma within it.
• High in silica, low in water vapor = High viscosity.
• The magma will clog the main vent, build up pressure and result in an explosion.
Life of a Volcano
• Extinct- has not erupted in recorded history
• Dormant- has erupted in recorded history, not currently erupting
• Active- is currently erupting
Batholith: Large igneous rock mass underneath mountains
Dike: Magma that cuts across preexisting rock
Laccolith: small pool of magma that collects just under Earth’s surface
Pluton: Intrusive igneous rocks formed by converging plates
Sill: Pool of solidified magma in between rock layers
Stock: Small batholith
Caldera: large crater formed from volcano collapse during or after it erupts
Crater: depression at volcano’s Summithttp://www.boston.com/bigpicture/2011/02/nyiragongo_crater_journey_to_t.html
Hot Spot: Hot area of a tectonic plate not along plate boundary
Tephra: Rock fragments thrown into the air during a volcanic eruption
Vent: Opening in Earth’s crust where lava erupts and flows outward
Pyroclastic Flow: Fast-moving cloud of ash, gas, and volcanic material after an eruption
Types of Volcanoes
• Cinder Cone
• Composite
• Shield
Composite Volcanoes
• Composed of alternating bands of pyroclastic material (volcanic fragments) and lava.
• Explosive eruptions• Andesitic magma (high
silica)• Example: Mt St Helens
and Mt. Rainier in the Cascade Range Mt St Helens
Pyroclasticmaterial
SolidifiedLava
Mt. Rainier
Shield Volcanoes
• Wide volcanoes, gentle slope
• Composed of layers of solidified magma
• Calm lava eruptions• Basaltic Magma (low
silica)• Example: Hawaiian
Islands
Solidified lava
Cinder Cone
• Composed of pyroclastic material (Tephra- volcanic fragments)
• Small and steep• Explosive eruptions (high silica)• Example: Paricutin in Mexico
PyroclasticMaterials
Volcanoes
• The majority of Earth’s surface
volcanoes are found along the Pacific
Plate Boundary- Ring of Fire.
-due to the subduction of the Pacific Plate.
Volcano Formation at Convergent Boundaries
Volcano Formation at Convergent Boundaries
Mt St. Helens
Mt. Pinatubo
Aleutian Islands
Volcanoes• Volcanoes also
form along the mid-ocean ridges
-due to upwelling of magma- long fissures in places
Volcano Formation at Divergent Boundaries
Volcano Formation at Divergent Boundaries
Iceland Volcanic ActivityBlack Smoker,Mid-Atlantic Ridge
Pillow Basalts,South Pacific
Volcano Formation NOT at Plate Boundaries: Hot Spot Volcanoes
The Islands of Hawaii
• These islands formed over a period of 5 million years.
• The islands are slowly moving to the northwest with a active hot spot currently under the island of Hawaii.
Plate Movement
Hot Spot
The Yellowstone Caldera is the volcanic caldera located in Yellowstone National Park in the United States, sometimes referred to
as the Yellowstone Supervolcano
Volcanic Hazards
• Lava Flows• Pyroclastic Flows• Lahars• Earthquakes• Tsunamis• Toxic Gases• Volcanic Bombs• Ash Falls• More…