Earthquakes Flashcards
(23 cards)
Define Earthquake
The vibration of Earth produced by the rapid release of energy
Fault
A break in rock mass along which movement has occurred (fracture in earths crust, horizontal and vertical)
Fracture in earths crust. Pressure builds up , when rocks finally move , energy is released as waves.
Liquefaction
A phenomenon, sometimes associated with earthquakes, in which soils and other unconsolidated materials containing abundant water are turned into a fluid like mass that is not capable of supporting buildings
Hazards associated with earthquakes
Structures collapsing , liquefaction,fire , ??
Elastic rebound
With stress, The sudden release of stored strain in rocks that results in movement along a fault , rock deform ( when fault slips, energy is released and rocks return to unstressed position but no longer line up )
Ring of fire
is a major area in the basin of the Pacific Ocean where a large number of earthquakes and volcanic eruptions occur.
Focus
The place where an earthquake starts , down beneath center
Epicenter
The point on earths surface directly above the focus
Richter scale
Measures energy released, is quantitative, every .2 represents doubling of energy . Ex: 5.2 earthquake releases twice the amount of energy as 5.0
Modified Mercali scale
How earthquake is perceived to humans, damage caused, more qualitative
Earthquakes in Oklahoma and probably cause
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New Madrid earthquakes (history, cause, chance of possible future problems )
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Type and characteristics of surface waves
? On surface, slower than body waves, caused the damage on surface
Type and characteristics of body waves
?travel through body of planet
P waves: primary waves, push – pull, like slinky, are fastest
S waves- secondary waves, shake, like jump rope, are slower, travel through solids only
Shadow zones
?The shadow zone is the area of the earth from angular distances of 104 to 140 degrees from a given earthquake that does not receive any direct P waves. The shadow zone results from S waves being stopped entirely by the liquid core and P waves being bent (refracted) by the liquid core.
What was found out about center of earth from waves
?S travels through solids only l, have S shadow zone, therefore know there is an outer core that is liquid
Layers: crust, mantle , outer core, inner core
How are epicenter location found
Can Learn from earthquake waves. Find difference in arrival of first P wave and first S wave, and use chart for distance, need 3 seismographs for direction
Wave refraction
?P shadow zone, waves travel at different speeds
refraction. Refraction is (1) the deflection, or bending, of the ray path of a seismic wave caused by its passage from one material to another having different elastic properties
Convection in mantle
?Mantle convection is the slow creeping motion of Earth’s solid silicate mantle caused by convection currents carrying heat from the interior of the Earth to the surface.
Three major earthquake zones
Pacific rim, mid oceanic ridges, and Mediterranean Himalayan
Seismograph and how it works
?instrument shakes with earth, pen attached loosely , measures energy released by earthquake
Tsunami
?speed decreases, wave height increases as waves near shore
Why few deep focus earthquakes
Because rocks are “plastic” as go deeper, less likely to be brittle and break. Also pressure is exerted in all directions in more fluid hotter rocks as go deeper
