MIDTERMS Flashcards
(35 cards)
a vent, hill or mountain from which molten or hot rocks with gaseous materials are ejected
Volcano
can be craters, hills or mountains formed by removal of pre-existing material or by accumulation of ejected materials
Volcano
erupted w/in historical times (last 600 yrs); has written historical accounts or oral tradition
Active
landform is young-looking but w/ no records or proof of eruption
Potentially Active
long-period inactivity is evident from too much weathering & erosion of deep & long
gullies (valleys)
Inactive
one that hasn’t erupted in the past 10,000 BUT which is expected to erupt
again
Dormant
one that nobody expects to ever erupt again (note there have been eruptions
from “extinct” volcanoes
Extinct
ultravulcanianeruptionorsteam-blast eruption, occurs when magma heats ground or surface water.
Phreatic Eruption
Veryviolenteruptiongeneratedbytheexplosivecontactof erupting magma with water; Voluminous, slightly tall ash columns, laterally-projected pyroclastic currents (base surges) & blasts
Phreatomagmatic
Characterized by a dense cloud of ash-laden gas exploding from the crater and rising high above the peak.
Vulcanian
Highlyexplosive,with dense clouds of gas and tephra being propelled
upwards for many kilometres;
Plinian
What are the types of Eruption?
Phreatic Eruption
Phreatomagmatic
Vulcanian
Plinian
What are the Volcanic hazards?
Tephra Fall Lava Flow Pyroclastic flow Lahars Volcanic Gases Ground Fissuring Debris Avalanche Volcanic Tsunami
Gravitational settling of volcanic ash & fragments from the umbrella clouds of tall eruption columns & ash clouds of pyroclastic flows
Tephra Fall
Incandescent rivers of hot molten rock (lava)
• Erupted from volcanic craters, fissures, during Hawaiian- Strombolian activity, lava dome eruptions
Lava Flow
Turbulent mass of ejected fragmented volcanic materials (ash & rocks) + hot gases that flow downslope at very high speeds (30-700 kph)
Pyroclastic Flow
Rapidly flowing thick mixture of volcanic sediments and water
• Triggered by rainfall, melting of craterial icecaps, lake breakout or hydrothermal
“squeezing”
Lahars
It illustrates thickness variations within a tabular unit, layer or stratum. Isopachs are contour lines of equal thickness over an area
Isopach map
Volcanic hazards zonation map
Show areas identified to be prone to a particular volcanic phenomena
• Tool to gauge the degree of susceptibility of a given area to a particular hazard
• Determine which areas should be evacuated and avoided during eruptions
• Provide guidelines for long-range land use planning around volcanoes that take
into account potential hazards from future eruption
an individual particle ejected during a volcanic eruption; usually classified according to size
Pyroclast
pertaining to clastic rock material formed by explosion from a volcanic vent; also pertaining to rock texture of explosive origin; not synonymous with adjective “volcanic”
Pyroclastics
- any rock consisting of unreworked solid material of whatever size explosively or serially ejected from a volcanic vent
Pyroclastic Rock
any volcanic material that is ejected into the air (ejecta).
Pyroclastic Materials
(32 mm diameter) and are solid when ejected
Blocks
