earthquake volcano test Flashcards
Earthquakes
shaking and trembling that results from sudden movement of part of the earths crust
– caused by the release of energy
causes of earthquakes
ground shakes from errupting volcano, collapse of a cavern, impact of a meteorite
major cause of an earthquake
stress that builds up and causes faulting
elastic rebound theory
rocks that are strained past a certain point will fracture and not spring back to their original shape
–produces most of our earthquakes
Focus
point Beneath the earth surface where the rocks breaker move apart
epicenter
Point on earth surface directly above the focus
–site of most violent shaking that can move in any direction
foreshocks
occur days or even years before an earthquake
aftershocks
continue for years after the main earthquake
surface waves
Along surface of Earth
body waves
move through interior
types of seismic body waves
P waves and S waves
P waves
primary – move the fastest – back-and-forth waves – push and pull waves – move through solid liquid or gas
S waves
secondary – travel slower – move up and down – travel through solids only
seismograph
instrument used to detect and measure seismic waves
seismogram
seismographs record of waves and has wavy lines recorded on a paper
– called a trace (image produced)
earthquake distance
The epicenter is located using the difference in the arrival times between P and S wave recordings which are related to distance
magnitude
amount of energy released at the earthquakes epicenter
Richter scale
measures how much energy on earth releases by assigning a number from 1 to 10
intensity
effect of an earthquake on the earth surface
–the amount of shaking produced
mercalli scale
measures the effect of an earthquake – scale based on how the effects of an earthquake or felt
earthquake. direction
need distance from three different stations in order to determine location
Pacific ring of fire
major earthquake zone that forms a ring around the Pacific ocean
liquefaction
conversion of soil into a fluid like mass during an earthquake or seismic event
tsunami
extremely large ocean wave caused by an earthquake on or near the ocean floor
successful earthquake prediction must correctly forecast
where will occur, when it will occur, and what magnitude it will be
possible methods for prediction of earthquakes
Micro quakes, behavior of animals, detect a slight tilting of ground before an earthquake, natural gas seepage
volcanism
any activity that includes the movement of magma toward the surface of the earth
volcano
place where magma reaches the surface
magma
liquid molten rock underground
–magmas with more gases have more explosive eruptions
lava
magma that reaches the surface
what does magma contain
dissolved gases such as water vapor, carbon dioxide, sulfur
viscosity
substances resistance to flow
–related to silica content, high silica means more viscous, as temperature increases viscosity decreases
vent
opening from which lava flows
crater
funnel shaped pit or depression at top of volcano
caldera
craters who’s walls have collapsed
pipe
conduit between magma chamber underground and surface
mid ocean ridge
lava flows out smoothly and fluidly from cracks
subduction zone
usually explosive
hotspots
areas of volcanic activity in the middle of a lithospheric plate
where are most active volcanoes found
The ring of fire
–plate boundaries in the Pacific ocean
how are volcanic eruptions measured
volcanic explosivity Index (VEI)
–scale value based on cloud high and amount of material ejected during eruption
Felsic
much silica, light colored, slow moving(continental crust)
mafic
Low silica, dark colored, fast moving (oceanic crust)
basaltic lava
comes from Mafic magma
types of basaltic lava
Aa lava
Pahoehoe
Aa lava
forms when lava flows rapidly, rough, jagged blocks with spiny projections
pahoehoe lava
forms when lava flow slowly
pillow lava
created under water, slow moving so outside cools while inside is Molten
tephra
solid fragment ejected from a volcano that are sometimes called pyroclastic material
ash
<2mm
tephra
lapilli
2<64mm
tephra
bombs
> 64mm
–aerodynamic in shape
(tephra)
blocks
> 64mm
–angular, blocky
(tephra)
shield volcano
composed of quiet lava flows, form gently sloping dome shaped mountain, basaltic(mafic) magma
Cindercone volcano
made mostly of tephra, formed from explosive eruptions, not very high, narrow base, steep sides
composite volcano
alternating layers of expelled rock and lava, violent, explosive eruptions at first with tephra, then quiet with lava, forms large cone shape mountains
EX MT FUGI
volcanic hazards
ash in the atmosphere, lahars, volcanic gases
ashen the atmosphere
can disrupt air travel and in severe instances affect climate
lahars
mudflows made up of volcanic debris, they flow like liquids and have a consistency similar to wet concrete, travel at speeds of over 50 mph
volcanic gases
most of the gas released in an irruption is harmless water vapor but volcanoes also produce carbon dioxide, sulfur dioxide, hydrogen sulfide, fluorine gas
