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SMT CHAPTER 5
NATURAL HAZARDS: KELLER/DEVECCHIO
93
Geology
10/10/2012

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Cards

Term
Molton rock within the earth is called__________, and when this materiel reach the surface it is called __________. Molton rock erupts onto earths surface through openings called ____________.
Definition
Magma

Lava

Vent
Term
Where are 2/3rds of volcanoes located ______________, and at what land feature are they also found in ?
Definition
ring of fire

mid-ocean ridges
Term
what causes the variation of magma consistency___________
Definition
Sinking/Spreading of tectonic plates
Term
It is a common misconception that plates move around on an ____________.
Definition
ocean of molten rock
Term
the reason the athenosphere is weak and able to flow, allowing rigid plates to move around the globe is that______________, it is close to its melting point.
Definition
it is not actually molton
Term
Decompression melting occurs when the overlying pressure exerted on hot rock within the asthenosphere is ______.

What keeps the earths mantle in a solid state, and far from the melting point?
Definition
Decreased.

The great pressure generated by rock layers
Term
Addition of volatiles lowers the melting temperature of rocks by helping to break________ within silicate minerals.

What are volatiles?
Definition
chemical bonds

chem compounds that evaporatea easily and exist in gaseous state.
Term
the released volatiles rise upward from the sub-ducting slab and interact with the formally dry asthenosphere and _____________.
Definition
induce melting and volcanism at the earths surface
Term
magma is composed of _____2______. the three major types of magma are_____3______.
Definition
Melted silicate rocks/ dissolved gasses.

basaltic, andestic, rhyolitic.
Term
what type of magma is high in silica content/low
Definition
andestic/ rhyoltic

basaltic
Term
rocks low in silica content is called_______, while those high in silica content is called_____________.
Definition
mafic

felsic
Term
magma is denser then surrounding rock T/F.
chemical processes as well as the addition of melt from surrounding rock tend to cause melt to evolve, and become more____________ over time.
Definition
felsic
Term
resistance to flow of fluid is called____________. as the lava travels down a volcanoes flank is cools and its viscosity___________. causing it to flow more slowly
Definition
viscosity

increases
Term
rhyolitic lava flows have ___________move slowly and may be a hundred feet thick, and are restricted to___________.
Definition
high viscosity

vent region
Term
basaltic lava flows___________,and are thin and may travel___________ from the vent
Definition
rapidly

10s of kilometers
Term
what is correlated to the volatile content of magma? this causes volcanoes to be either peaceful or violent
Definition
viscosity
Term
a high concentration of dissolved volatiles within the__________will cause an___________ when the melt is decompressed when it reaches earths surface.
Definition
magma

explosive eruption
Term
andesitic to rhyoltic magma has more dissolved gas, and volcanoes with more of this magma are more prone to ___________ then volcanoes erupting basaltic lava
Definition
explosive eruptions

Term
rapid bubble formation, degassing of viscous magma breaks apart the molten materiel into ____________, and these are examples of ________2______
Definition
ash fragments

pyroclastic debris, tephra
Term
debris make up many sizes
0.1 in =

0.1-2.5in=

2.5 in=

accumulation of debris is called_____________, and can be fused into _________
Definition
particles

lapilli

bombs

pyroclastic deposition

pyroclastic rock

Term
shield volcanoes are the__________on earth, these volcanoes generally have_________ as a result of low viscosity and low volatile content of basaltic magma.
Definition
largest volcanoes

non-explosive
Term
shield volcanoes are_________ then they are tall, and make up the tallest mountains on earth
Definition
more wider
Term
magma can move for many kilometers through underground __________ which are close to the surface. the tubes________ the magma keeping it hot.
Definition
lava tubes

insulate
Term
magma from __________ are generally more viscous and has a higher volatile content then shield volcanoes. this type of volcano has a_______shape.
Definition
composite volcanoes

cone
Term
composite volcanoes erupt a variety of_____________and may be intermediate between_______.

these volcanoes have produced the most deaths from eruptions T/F, and produce what type of blast.
Definition
lava types

andesite/rhyolite

true

lateral
Term
this type of volcano has highly viscous magma, exhibit highly explosive eruptions are called____________.

smaller versions of this volcano type consist of_____________often form within the volcanic crater created during the eruption.
Definition
volcanic domes

degassed felsic lava
Term
this volcano is composed of small pieces of red or black lava is called_________. where are these volcanoes common?
Definition
cinder cones

on flanks of large volcanoes along faults/cracks/ fissures
Term
how are craters formed, and they remove what from volcanoes.
Definition
by explosion

the upper portion
Term
gigantic depressions formed during explosive ejection of magma and subsequent collapse of upper cone are known as__________.
Definition
calderas
Term
a volcanic vent is any opening through which____2_______ are erupted

vents may be_______ or__________

accumulations on this land feature is called_________
Definition
lava/pyrolclastic debris

circular/ elongated

flood basalts
Term
when groundwater comes into contact with hot rock it becomes heated and can discharge as__________2____________. when groundwater boils in an underground chamber to produce periodic steam driven release of steam and hot water at the surface a phenomenon called a_________ is formed.
Definition
hot spring/thermal spring

geyser
Term
caldera eruptions have been termed_______ but this term is__________
Definition
super volcanoes

not accepted by scientists.
Term
a large caldera forming eruption may explosively extrude 240 miles cubed of_____________ consisting of ash.
Definition
pyroclastic ash
Term
the main events in a caldera producing eruption can occur__________, but lesser magnitude activity can linger on for___________
Definition
quickly, few days/weeks

a million years

Term
geysers/hot springs are considered__________ because their floors have slowly domed upward since the explosive eruptions that formed them
Definition
resurgent claderas
Term
approxamitely 3/4ths of all lava erupted on earth is extruded from undersea _______________. This magma mixes verry little with other materials except ____________. therefore the resultant lavas are composed entirely of ______________.
Definition
mid ocean ridges

balsaltic oceanic crust

low viscosity basalt
Term
composite volcanoes are associated with subduction zones and thus are the _______________ found around the pacific rim. these volcanoes are commonly _____________ in composition. The higgher silica content and higher ___________ make these volcanoes explosively unpredictable.
Definition
most common

andestic

volatile content
Term
where are shield volcanoes formed? the lava in this volcanoe can be stationary for how many years?
Definition
ABOVE HOTSPOTS

many millions of years
Term
in hotspots beneath continents _____________ eruptions occur in this tectonic setting. These are generally low in activity T/F, and they are associated with rhyoltic magma.
Definition
caldera forming

F
Term
rhyolite has a __________ silica content produced when rising magma from the asthenosphere ___________ with felsic continental crust.
Definition
High

Melts/mixes
Term
the effects of a large caldera explosion in Wetern U.S or canada would liely be felt____________ from its source, and in the form of ______________ in the atmosphere.
Definition
far from its source

ash fall and ash clouds
Term
Eruptions in the U.S occur __________ per year, and mostly in ________________. these usually go off in ____________ populated places.
Definition
two or three times

Alaska

sparsely
Term
in the last 100 years ___________ people have died from volcanic eruptions.
Definition
100,000
Term
Primary effects of volcanoe hazards_________5__________

secondary effects are______________7_____________
Definition
lava flow, ash fall, pyroclastic flows, lateral blasts, and release of gases.

debris flows, mudflows, landslides, debri avalanches, floods, fires,and tsunamis.
Term
lava flow results when magma reaches the surface overflows the central crater or erupts from a vent____________.
Definition
along flank of the volcanoe
Term
what type of lava flow has a smooth, sometimes ropey texture?

what type of lava flow has a blocky surface texture after hardening?
Definition
pahoehoe

aa
Term
how is black sand made
Definition
when molton lava enters cold ocean water
Term
pyrolclastic activity refers to ___________ volcanisim in which tephra is ________ from a volcanic ventb into the atmosphere.
Definition
explosive

physically blown
Term
when a tremendous amount of fine grained rock and volcanic glass shatters, and gas is blown high in the air by volcanic explosions is called___________. these particles are carried downwind and settle to produce _____________.
Definition
volcanic ash eruptions

ash fall
Term
when part of a volcanoe is deestroyed and gas, ash, rock frags are blown horizontally from the side of a mountain is called____________.
Definition
lateral blast
Term
avalanches of hot pyroclastic materials such as ash, rock, volcanic glass, and gas are blown out of a vent and move rapidly down the sides of a volcanoe is called_____________.
Definition
pyroclastic flows
Term
pyroclastic flows move at__________KM/MI per hour, and are _______degress celcious/farenheight.
Definition
160km/100 mi

99-600/210-1100
Term
what are the reprucussions of ash fall _________5__________
Definition
vegetation destroyed

water contamination

structure dmg from ash pilling on roofs

respritory irritation

aircraft failure
Term
what are the 4 hazardous gases emitted during volcanoes.
Definition
CO2, CO, SO2, H2S (hydrogen sulfide)
Term
sulfer dioxide that reaches the atmosphere can cause what?
Definition
acid rain
Term
volcanoes can create air pollution which can effect large areas, and these are known as____________
Definition
VOG
Term
what causes irritation/ damage to eyes when haze from steam explosions reachs the atmosphere.
Definition
hydrodgen chloride gas, tiny glass fragments
Term
the 2 most dangerous forms of secondary effects of volcanic eruptions are ____________.
Definition
debri flows, mudflows.
Term
when large amounts of of loose volcanic ash and other tephra are saturated with water, become unstable, and suddenly move downslope produces ____________.
Definition
lahars
Term
lahars can occur W/O an __________, and are generally ___________ flows.
Definition
eruption

low temperature.
Term
even relatively small eruptions of hot volcanic material may quickly melt large volumes of _______________ on a volcano. This rapid melting produces a flood of meltwater that___________ the slope of the volcano to create______________.
Definition
snow/ice

erodes

debris flow
Term
gigantic mudflows have originated on the flanks of volcanoess in the pacific northwest in both ___________ times.
Definition
hisotric/prehistoric.
Term
how will a victim see a mudflow? and at what speed?
Definition
they will see a wall of mud as high a ranch house

apprx 20 MPH
Term
the USGS has placed monitors in severall locations, and these systemsc use what means to monitor activities of lahars
Definition
acoustic flow monitors.
Term
can volcanic landslides occur W/O an eruption ?
Definition
YES
Term
how long was Mt St. Helens dormant untill 1980? why did it erupt?
Definition
120 years

seismic activity/ small explosions
Term
the MT. saint helens explosion's blast traveled at ______________ and devastated about ___________of forest.the vertical cloud which followed was_____________ high.
Definition
300 MPH

230 square miles

12 miles
Term
the flows from Mt Saint helens traveled at __________ MPH.

the top of Mt saint helens was reduced by how many feet?

what was the estimated $ of damage created?
Definition
29-55

1314 Ft

1 billion
Term
what commonly accompanys/ preceds volcanic eruptions as magma rises through earths crust?
Definition
earthquakes
Term
what are the most common side effects of volcanic activity?
Definition
landslides
Term
a global cloud of sulferic aciddroplets are refered as ____________
Definition
aerosols
Term
volcanoes contribute to the atmosphere, and giving life on eartg by?

what resources do volcanoes provide us?
Definition
giving water vapors and gases

fertile solis, power source, minerals
Term
volcanic soils provide a great_____________ for plants such as coffe, corn, pinapple, sugar cane, and grapes.
Definition
growth medium
Term
the internal heat associated with volcanoes can be used to create _____________ for urban communities. Is this resource renewable Y/N
Definition
power

Yes
Term
volcanisim is the source and volcanic rocks are the host for___________. which iclude concentrations of minerals. volcanic rocks are also used in soaps, building stone, aggregate for roads and railrods, oil, gas drilling mud, landscaping gravel, cieling tile, cement, plaster, cat liter.
Definition
mineral resources
Term
volcanoes are responsible for___________. WOULD ISLANDS SUCH AS hAWAII EXIST w/o VOLCANOES ?
Definition
CREATING MUCH OF THE LAND WE INHABIT.

NO
Term
do any human activities affect volcanoes?
Definition
No
Term
for forecasting what is needed before the mechnasim is understood
Definition
Actual eruptions
Term
below a volcano as upward moving of magma fractures the surrouinding rock and gas bubbles in the magma form and burst produces what degree of earthquake?
Definition
shallow earhtquakes
Term
in a reawakening of a volcano the magma must do what to work its way to the surface.
Definition
fracture/ break solid igneous rock
Term
prior to a volcanic eruption, a large volume of magma accumulates in a holding reservoir beneath the volcano. the hot materail does what three things?
Definition
Local magnetic, thermal, geochemical conditions.
Term
the magnetic properties within rocks may change when_____________.
Definition
older rock is heated by new magma
Term
what CHANGES in regards to gas emissions is used to monitor them?
Definition
changes in carbon dioxide, sulfer dioxide, gas emission rates.
Term
the primary toool for reconstructing geologic history is _____________ of volcano rocks and deposits.
Definition
geologic mapping
Term
what does geologic mapping and dating of volcanic events is that it allows the preparation of ________ to assist in__________, and disaster preparedness.
Definition
hazard maps


land use planning
Term
Definition
Term
what two ways does the USGS use to establish an alert notification system.
Definition
ground based alerts

aviation based code levels
Term
how many of the 170 active volcanoes in the U.S does the USGS monitor.
Definition
50
Term
what are the four reasons people willingly live in the proximity of volcanoes?
Definition
were born there

fertile soil

optimistic of their chances

cant choose where tehy live
Term
a volcanic crisses can develop when scientists ______ that an eruption is ___________near future.
Definition
predict

likely in the
Term
what two measures are used to deflect lava away from populated/ valuable areas.
Definition
hydraulic chilling

wall construction
Term
when it comes to controlling lava flow what are three favorable conditions?
Definition
slow movement of flows

easy transport/delivery of flow controlling assets

water readily available
Term
Definition