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 ____________. |
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Definition
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Term
| Where are 2/3rds of volcanoes located ______________, and at what land feature are they also found in ? |
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Definition
ring of fire
mid-ocean ridges |
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Term
| what causes the variation of magma consistency___________ |
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Definition
| Sinking/Spreading of tectonic plates |
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Term
| It is a common misconception that plates move around on an ____________. |
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Definition
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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. |
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Definition
| it is not actually molton |
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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? |
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Definition
Decreased.
The great pressure generated by rock layers |
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Term
Addition of volatiles lowers the melting temperature of rocks by helping to break________ within silicate minerals.
What are volatiles? |
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Definition
chemical bonds
chem compounds that evaporatea easily and exist in gaseous state. |
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Term
| the released volatiles rise upward from the sub-ducting slab and interact with the formally dry asthenosphere and _____________. |
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Definition
| induce melting and volcanism at the earths surface |
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Term
| magma is composed of _____2______. the three major types of magma are_____3______. |
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Definition
Melted silicate rocks/ dissolved gasses.
basaltic, andestic, rhyolitic. |
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Term
| what type of magma is high in silica content/low |
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Definition
andestic/ rhyoltic
basaltic |
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Term
| rocks low in silica content is called_______, while those high in silica content is called_____________. |
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Definition
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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. |
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Definition
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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 |
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Definition
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Term
| rhyolitic lava flows have ___________move slowly and may be a hundred feet thick, and are restricted to___________. |
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Definition
high viscosity
vent region |
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Term
| basaltic lava flows___________,and are thin and may travel___________ from the vent |
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Definition
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Term
| what is correlated to the volatile content of magma? this causes volcanoes to be either peaceful or violent |
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Definition
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Term
| a high concentration of dissolved volatiles within the__________will cause an___________ when the melt is decompressed when it reaches earths surface. |
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Definition
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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 |
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Definition
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Term
| rapid bubble formation, degassing of viscous magma breaks apart the molten materiel into ____________, and these are examples of ________2______ |
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Definition
ash fragments
pyroclastic debris, tephra |
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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 _________ |
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Definition
particles
lapilli
bombs
pyroclastic deposition
pyroclastic rock |
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Term
| shield volcanoes are the__________on earth, these volcanoes generally have_________ as a result of low viscosity and low volatile content of basaltic magma. |
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Definition
largest volcanoes
non-explosive |
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Term
| shield volcanoes are_________ then they are tall, and make up the tallest mountains on earth |
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Definition
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Term
| magma can move for many kilometers through underground __________ which are close to the surface. the tubes________ the magma keeping it hot. |
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Definition
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Term
| magma from __________ are generally more viscous and has a higher volatile content then shield volcanoes. this type of volcano has a_______shape. |
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Definition
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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. |
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Definition
lava types
andesite/rhyolite
true
lateral |
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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. |
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Definition
volcanic domes
degassed felsic lava |
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Term
| this volcano is composed of small pieces of red or black lava is called_________. where are these volcanoes common? |
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Definition
cinder cones
on flanks of large volcanoes along faults/cracks/ fissures |
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Term
| how are craters formed, and they remove what from volcanoes. |
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Definition
by explosion
the upper portion |
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Term
| gigantic depressions formed during explosive ejection of magma and subsequent collapse of upper cone are known as__________. |
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Definition
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Term
a volcanic vent is any opening through which____2_______ are erupted
vents may be_______ or__________
accumulations on this land feature is called_________ |
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Definition
lava/pyrolclastic debris
circular/ elongated
flood basalts |
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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. |
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Definition
hot spring/thermal spring
geyser |
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Term
| caldera eruptions have been termed_______ but this term is__________ |
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Definition
super volcanoes
not accepted by scientists. |
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Term
| a large caldera forming eruption may explosively extrude 240 miles cubed of_____________ consisting of ash. |
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Definition
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Term
| the main events in a caldera producing eruption can occur__________, but lesser magnitude activity can linger on for___________ |
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Definition
quickly, few days/weeks
a million years |
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Term
| geysers/hot springs are considered__________ because their floors have slowly domed upward since the explosive eruptions that formed them |
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Definition
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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 ______________. |
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Definition
mid ocean ridges
balsaltic oceanic crust
low viscosity basalt |
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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. |
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Definition
most common
andestic
volatile content |
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Term
| where are shield volcanoes formed? the lava in this volcanoe can be stationary for how many years? |
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Definition
ABOVE HOTSPOTS
many millions of years |
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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. |
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Definition
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Term
| rhyolite has a __________ silica content produced when rising magma from the asthenosphere ___________ with felsic continental crust. |
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Definition
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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. |
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Definition
far from its source
ash fall and ash clouds |
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Term
| Eruptions in the U.S occur __________ per year, and mostly in ________________. these usually go off in ____________ populated places. |
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Definition
two or three times
Alaska
sparsely |
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Term
| in the last 100 years ___________ people have died from volcanic eruptions. |
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Definition
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Term
Primary effects of volcanoe hazards_________5__________
secondary effects are______________7_____________ |
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Definition
lava flow, ash fall, pyroclastic flows, lateral blasts, and release of gases.
debris flows, mudflows, landslides, debri avalanches, floods, fires,and tsunamis. |
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Term
| lava flow results when magma reaches the surface overflows the central crater or erupts from a vent____________. |
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Definition
| along flank of the volcanoe |
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Term
what type of lava flow has a smooth, sometimes ropey texture?
what type of lava flow has a blocky surface texture after hardening? |
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Definition
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Term
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Definition
| when molton lava enters cold ocean water |
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Term
| pyrolclastic activity refers to ___________ volcanisim in which tephra is ________ from a volcanic ventb into the atmosphere. |
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Definition
explosive
physically blown |
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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 _____________. |
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Definition
volcanic ash eruptions
ash fall |
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Term
| when part of a volcanoe is deestroyed and gas, ash, rock frags are blown horizontally from the side of a mountain is called____________. |
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Definition
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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_____________. |
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Definition
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Term
| pyroclastic flows move at__________KM/MI per hour, and are _______degress celcious/farenheight. |
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Definition
160km/100 mi
99-600/210-1100 |
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Term
| what are the reprucussions of ash fall _________5__________ |
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Definition
vegetation destroyed
water contamination
structure dmg from ash pilling on roofs
respritory irritation
aircraft failure |
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Term
| what are the 4 hazardous gases emitted during volcanoes. |
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Definition
| CO2, CO, SO2, H2S (hydrogen sulfide) |
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Term
| sulfer dioxide that reaches the atmosphere can cause what? |
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Definition
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Term
| volcanoes can create air pollution which can effect large areas, and these are known as____________ |
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Definition
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Term
| what causes irritation/ damage to eyes when haze from steam explosions reachs the atmosphere. |
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Definition
| hydrodgen chloride gas, tiny glass fragments |
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Term
| the 2 most dangerous forms of secondary effects of volcanic eruptions are ____________. |
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Definition
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Term
| when large amounts of of loose volcanic ash and other tephra are saturated with water, become unstable, and suddenly move downslope produces ____________. |
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Definition
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Term
| lahars can occur W/O an __________, and are generally ___________ flows. |
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Definition
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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______________. |
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Definition
snow/ice
erodes
debris flow |
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Term
| gigantic mudflows have originated on the flanks of volcanoess in the pacific northwest in both ___________ times. |
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Definition
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Term
| how will a victim see a mudflow? and at what speed? |
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Definition
they will see a wall of mud as high a ranch house
apprx 20 MPH |
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Term
| the USGS has placed monitors in severall locations, and these systemsc use what means to monitor activities of lahars |
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Definition
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Term
| can volcanic landslides occur W/O an eruption ? |
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Definition
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Term
| how long was Mt St. Helens dormant untill 1980? why did it erupt? |
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Definition
120 years
seismic activity/ small explosions |
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Term
| the MT. saint helens explosion's blast traveled at ______________ and devastated about ___________of forest.the vertical cloud which followed was_____________ high. |
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Definition
300 MPH
230 square miles
12 miles |
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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? |
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Definition
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Term
| what commonly accompanys/ preceds volcanic eruptions as magma rises through earths crust? |
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Definition
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Term
| what are the most common side effects of volcanic activity? |
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Definition
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Term
| a global cloud of sulferic aciddroplets are refered as ____________ |
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Definition
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Term
volcanoes contribute to the atmosphere, and giving life on eartg by?
what resources do volcanoes provide us? |
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Definition
giving water vapors and gases
fertile solis, power source, minerals |
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Term
| volcanic soils provide a great_____________ for plants such as coffe, corn, pinapple, sugar cane, and grapes. |
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Definition
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Term
| the internal heat associated with volcanoes can be used to create _____________ for urban communities. Is this resource renewable Y/N |
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Definition
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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. |
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Definition
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Term
| volcanoes are responsible for___________. WOULD ISLANDS SUCH AS hAWAII EXIST w/o VOLCANOES ? |
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Definition
CREATING MUCH OF THE LAND WE INHABIT.
NO |
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Term
| do any human activities affect volcanoes? |
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Definition
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|
Term
| for forecasting what is needed before the mechnasim is understood |
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Definition
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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? |
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Definition
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Term
| in a reawakening of a volcano the magma must do what to work its way to the surface. |
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Definition
| fracture/ break solid igneous rock |
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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? |
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Definition
| Local magnetic, thermal, geochemical conditions. |
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Term
| the magnetic properties within rocks may change when_____________. |
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Definition
| older rock is heated by new magma |
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Term
| what CHANGES in regards to gas emissions is used to monitor them? |
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Definition
| changes in carbon dioxide, sulfer dioxide, gas emission rates. |
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Term
| the primary toool for reconstructing geologic history is _____________ of volcano rocks and deposits. |
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Definition
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Term
| what does geologic mapping and dating of volcanic events is that it allows the preparation of ________ to assist in__________, and disaster preparedness. |
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Definition
hazard maps
land use planning |
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Term
| what two ways does the USGS use to establish an alert notification system. |
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Definition
ground based alerts
aviation based code levels |
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Term
| how many of the 170 active volcanoes in the U.S does the USGS monitor. |
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Definition
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Term
| what are the four reasons people willingly live in the proximity of volcanoes? |
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Definition
were born there
fertile soil
optimistic of their chances
cant choose where tehy live |
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Term
| a volcanic crisses can develop when scientists ______ that an eruption is ___________near future. |
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Definition
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Term
| what two measures are used to deflect lava away from populated/ valuable areas. |
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Definition
hydraulic chilling
wall construction |
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Term
| when it comes to controlling lava flow what are three favorable conditions? |
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Definition
slow movement of flows
easy transport/delivery of flow controlling assets
water readily available |
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