Earthquakes Flashcards
Define the elastic rebound theory
As the Earth’s crust deforms, the rocks which span the opposing sides of a fault are subjected to shear stress.
Define Focus and Epicenter and their relationship**test question
Focus is where that energy or slippage started
The epicenter is the point of the earths surface that is directly above the focus.
Define induced seismicity
refers to earthquakes related to human activity, such as the extraction or injection of fluids in the subsurface. Very common in fracking sites.
Define seismogaphs and seismograms***test question
Seismographs record seismic waves, ***remember seismic waves travel at different speeds.
seismogram: records of seismic waves,
What is an earthquake
Earthquakes are like shock (seismic) waves, in other words vibrations within the earth.
They are triggered by a sudden slippage of a rock along fault planes in the crust or mantle. The larger the displacement the more seismic energy is released.
Define seismic waves
The energy released during earthquakes pulverizes rocks, generates heat and causes vibrations which = seismic waves
What are surface and body waves
Surface waves do most of the damage, the stronger the surface waves are based off shallower focus points. They are produced by body waves.
Body waves are broken into two categories: Primary and Secondary waves.
What is a primary wave
Primary or compressional waves, are the fastest form of waves. Can pass through solids and liquid objects.
What is a secondary wave
Secondary or shear wave, are slower than P-waves. They pass through solids but not fluids.
How do we know the outer core is liquid*** test question
Because Shear waves cannot pass through the core thus the core must be liquid. This can be determined through Shadow zones, which are created when S waves refract off a certain angle of the outer core.
How do seismographs help determine epicenter and focus locations*** look in textbook because he sucked at teaching it.
By correlating the speed of waves from two different seismographs, you can determine the speed of the waves. With a third seismograph station, you can pinpoint the exact location of the epicenter
Define the Richter Scale
The richter scale is logarithmic so each increase in one unit is 10x seismic wave amplitude, however the energy release is 32 times greater.
Final question. liquification
A phenomenon in which the strength and stiffness of a soil is reduced by earthquake shaking or other rapid loading.
Where are earthquakes usually confined too
99% of epicenters are confined to seismic belts, like the ring of fire.
