26 terms

Volcano's Web Quest Vocabulary

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Volcano
Weak spot in the Earth's crust where magma rises to the surface
Pahoehoe
The low velocity of lava flows means that the skin that forms by air-cooling is not disrupted during flow and can maintain its smooth, unbroken, well-insulating surface. Shapes vary.
Lava
Mixture of melted rock and gases on the surface of earth
Crater
large, bowl-shaped cavity at the top of a volcano
Magma
Mixture of melted rock and gases below Earth's surface
Aa
lava that forms when lava flows rapidly. Under these circumstances, there is rapid heat loss and a resulting increase in viscosity. When the solid surface crust is torn by flow, the underlying lava is unable to move sufficiently rapidly to heal the tear. Bits of the crust are then tumbled in and coated by still liquid lava, forming the chunks.
volcano Vent
smaller opening where magma leaves volcano
volcano Pipe
Tube that connects magma chamber to Earth's surface
Pyroclastic Flow
hot, fast-moving cloud of ash and cinder
Magma Bomb
Giant chunk of magma thrown out of a volcano
Magma Chamber
Pocket where magma collects
Island Arc
String of islands created by volcanoes near plate boundaries
Hot Spot
area where material from deep within the mantle rises then melts, forming magma, and a volcano on top
quiet eruption
magma flows easily and quietly - contains pahoehoe and aa
dormant volcano
not active but may become active
explosive eruption
magma builds up pressure and explodes creating pyroclastic flows and magma bombs
extinct volcano
unlikely to erupt again
composite volcano
tall, cone-shaped mountains in which layers of lava alternate with layers of ash
lahar
volcanic mud flow
Volcanic Activity Measuring Equipment
seismograph, GPS, gas spectrometer, satellites. key ingredients are seismic monitoring, gas monitoring, and deformation studies.
cinder cone
a small volcano built primarily of pyroclastic material ejected from a single vent
shield volcano
a wide, gently sloping mountain made of layers of lava and formed by quiet eruptions
lava dome
raised mound of hardened lava, formed form magma pushing up from under the surface
tephra
bits of rock or solidified lava dropped from the air
lava flows
sheets of lava that flow onto the ground surface and bury or burn everything in their path
earthquakes
are caused by magma chambers filling up and causing the ground to swell

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