Test two Flashcards
Mount Pelee
Proclastic flows into St. Pierre, so fast it skipped across the ocean and into the harbor.
Krakatoa
Composite volcano, sound of explosion could be heard over 3,100 miles. over 36,000 died mostly by tsunami
Nevado Del Ruiz
Lahar killed over 20,000 people - 1985
Mount Rainier
People are living in Lahar pathways, lava flows, and pyroclastic flows. Stratovolcano with viscous lava
Tambora, Indonesia
was 13,000 ft tall, after explosion 8,700 ft tall. 4 mile wide caldera, 10,000 died from pyroclastic flow, 17,000 through disease and famine. Year without a summer.
Lake Nyos
accumulated and released immense voumes of carbon dioxide. Gas is now slowly vented out. Killed 3,000 cattle and many people
Yellowstone
Is a huge caldera. Mantle plume located below North American plate (NW Wyoming)
Vesuvius
a deadly combo
Mauna Loa
Largest shield volcano in the world
Pillow Basalt
bulbous or pillow shaped blobs from lava cooling underwater
define pyroclastic material
Molten and solid materials ejected upward and outward
Temperature of basaltic lava is?
hot! higher than all others
SiO4 content
pyramid shaped molecules, form crystals as magma cools. Lots of crystals with cooler temperature magma.
Viscosity is affected by…
Temperature, SiO4 content, volatiles
low gas content, low viscosity produces?
lava flows
high gas content, low viscosity produces?
lava fountains
Low gas content, high viscosity produces
very slow flow
high gas, high viscosity
Explosive!
Classify volcanoes based on…
shape and composition, relative activity, eruptive sytle
what is a shield volcano?
a broad, gently sloping volcanic mountain composed of basaltic lava flows
what is a cinder cone?
a small, very steep sloping volcano made up of pyroclastic material.
what is a composite volcano?
a large, steep, cone-shaped volcanic mountain composed of alternating layers of lava flows and pyroclastic material
what is a lava dome?
a small, dome or irregular shaped volcano composed of thick, viscous rhyolitic magma and lava
what is a flood basalt?
a vast accumulation of layers of basalt which may cover thousands of square miles. found at mid-ocean spreading centers or on continents as fissures.
what is an active volcano?
volcano is erupting, or is expected to soon.
What is a dormant volcano?
not presently active, but it has erupted during recorded history. still attached to a source of magma
what is an extinct volcano?
not erupting, is no longer connected to a source of magma
divergent boundaries have…
low SiO4 content, low gas, low viscosity, basaltic magma from mantle
oceanic-continental convergent boundaries can produce…
continental volcanic arcs with plug domes or composite volcanoes
oceanic-oceanic convergent boundaries can produce
composite volcanoes
define a hot spot
an area of volcanic activity above a mantle plume
define a mantle plume
a column of very hot magma that rises from the lower portions of the mantle
Vestmannaeyjar harbor, iceland
lava flowing from ocean, could block harbor. used fire dept. equipment to cool rock and make a levy
define a lahar
a flood of ash, mud, and water that flows down the side of a volcano. Created by melting snow and ice from the warming of a volcano
define a jokulhaup
a flood of water caused by volcanic activity under glacial ice
define a caldera
a large, basic-shaped depression created when a volcano explodes or collapses.
define a tsunami
a very long-wavelength ocean wave caused by oceanic disturbances (earthquakes, volcanoes)
