volcanoes test Flashcards
shaking and trembling that results from sudden movement of part of the earth’s crust
Earthquake
earthquakes are caused by…
- ground shakes from erupting volcano
- collapse of cavern
- impact of meteor
- stress that builds up and causes faulting
rocks that are strained past a certain point will fracture and not spring back to their original shape(produces most of our earthquakes)
Elastic Rebound Theory
point beneath the earth’s surface where the rocks break or move apart
focus
point on earth’s surface directly above the focus (site of most violent shaking)
epicenter
shaking that occurs days or even years before an earthquake
foreshock
shaking that occurs even years after earthquakes
aftershock
waves along the surface of earth
surface waves
waves that move through the interior of earth
body waves
- arrive first
- back and forth waves
- move through liquid, gas or solid
- slinky
P-waves
- arrive second
- up and down
- jumprope
- move through solids only
S-waves
instrument that detects and measures seismic waves
seismograph
seismograph’s record of waves; has wavy lines recorded on paper (also called trace)
seismogram
the epicenter is located using the difference in the arrival times between P and S wave recordings, which are related to distance
Earthquake Distance
amount of energy released at the earthquakes epicenter
Magnitude
measures how much energy an earthquake releases by assigning a number between 1-10
Richter scale
measures the effect of an earthquake; scale based on how the effects of an earthquake are felt
mercalli scale
effect of an earthquake on earth’s surface (amount of shaking produced)
Intensity
need difference from __ different stations to determine the location of an earthquake
3
major earthquake zone that forms a ring around the pacific ocean
pacific ring of fire
conservation of soil into a fluid like mass during an earthquake or seismic event
Liquefaction
extremely large ocean wave caused by an earthquake on or near the ocean floor
tsunami
Successful earthquake prediction must correctly forecast..
- where it will occur
- when it will occur
- what magnitude it will be
possible methods of predictions
- microquakes
- behavior of animals
- slight tilt in ground before earthquake
- natural gas seepage
any activity that includes the movement of magma toward the surface of earth
Volcanism
place where magma reaches surface
volcano
liquid molten rock underground
magma
magma that reached the surface
lava
what are magmas made up of ?
water vapor, CO2 and sulfur
magmas with more gases have more..
EXPLOSIVE ERUPTIONS!!!!!!!!!!!!
a substance’s resistance to flow
-related to silica content
viscosity
high silica=…
more viscous
as temp increases, viscosity _____
decreases
opening from which lava flows
vent
funnel shaped pit or depression at the top of volcano
crater
craters whose walls have collapsed
caldera
conduit between magma chamber underground and surface
pipe
occurs where plates are moving apart
-lava flows out fluidly from cracks(div. bound)
mid-ocean ridge
occurs at convergent boundaries and usually explosive
subduction zone
areas of volcanic activity in the middle of lithospheric plates
hot spots
most active volcanoes are found at …
The Ring of Fire
volcanic eruptions can be measured by the…
Volcanic Explosivity Index
Volcanic Explosivity Index scale value is based on…
cloud height and amount of material ejected during eruption
- much silica
- light colored
- slow moving
felsic lava type
- low silica
- dark colored
- fast moving(oceanic crust)
mafic lava type
comes from mafic lava
Basaltic lava
- Aa (ah-ah) lava
- forms when lava flows rapidly
- rough, jagged blocks with spiny projection
Basaltic lava
forms when lava flows slowly
Pahoehoe
created underwater, slow moving, inside is still gooey
pillow lava
solid fragments ejected from a volcano
tephra
tephra is also called
pyroclastic material
<2mm
ash
2<64mm
lapilli
> 64mm (aerodynamic by shape)
bombs
> 64mm (angular, blocky)
blocks
- composed of quiet lava flows
- form gently sloping
- dome shaped mountains
- basaltic (mafic) magma
shield volcano
- made up of mostly tephra
- explosive eruptions
- not very high
- narrow base
- steep sides
cindercone volcano
- alternating layers of expelled rock and lava
- violent eruptions at first w tephra, then quiet w lava
- large, cone shaped
composite volcano
what impact does ash in the atmosphere make?
- disrupt air travel
- if severe can affect climate
mudflows made up of volcanic debris
- flow like liquid(wet concrete)
- can travel over 50 mph
lahar
- mostly water vapor
- CO2
- sulfur dioxide
- hydrogen sulfide
- fluorine gas
volcanic gases
