Earthquakes Flashcards
Where do EQs commonly occur?
Along plate boundaries
What causes EQs
release of energy when the ground ruptures and moves along a fault
What are faults?
Cracks in the earth which we see movement in
What are the different types of faults?
Reverse, Normal, and strike slip
The shaking assosiated with EQs is:
Series of energy waves (seismic waves) that release from the hypocenter (focus)
The epicenter is:
the surface location (directly above) of the hypocenter/focus.
What is elastic rebound theory?
pressure is placed on rock by fault and as strain and tension builds and deforms rock. If strain gets to high the rock breaks and releases built up strain in seismic waves
How does the elastic rebound theory work?
based on rocks behaving like a stretching rubber band and once pressure is released the rock goes back to how it looked
Where are shallow EQs
divergent and transform boundaries (divergent: plate moving apart)(Transform: plates slide past horizontally)
Where do intermediate and deep EQs form?
convergent boundaries (plates colide)
What do EQs at mid-ocean ridges look like?
Shallow and low energy. occur along active portion of boundary (strike slip faults common)
What to EQs at continental transform boundaries look like?
occur in shallow crust and cause major disasters.
What do EQs at continental divergent boundaries look like?
rifts occur where tension and stretching creates normal faults. Rifting generates small shallow EQs.
What do EQs look like at convergent plate boundary subduction zones?
Shallow, intermediate, and deep EQs in characteristic pattern. linked with tsunamis and are deadly.
How do subduction zone EQs form?
Faults form where underground slab bends and large thrust faults occur at contact between plates. subduction slab bends overriding slab and it can snap back making huge EQ.
At what point point below ground do EQs become rare and why?
660 km cause mantle is too hot and ductile to break and make EQ
How do EQs appear convergent plate continent-continent collision zones?
continental lithosphere (crust and upper mantle) compresses along thrust faults. EQs can be very large.
What are intraplate EQs?
EQs not near modern plate boundaries. mostly in crustal weakness related to failed rifts or former shear zones. Around 5% of all EQs.
What are body waves?
Seismic waves that move through the interior of the earth.
What are the two types of body waves?
P waves and s waves
What does P wave stand for
Primary
What does s wave stand for
Secondary
How does a P wave travel
By compressing and expanding material parallel to the travel direction LIKE A SLINKY
How does a S wave travel
By moving material back and forth or up and down perpendicular to the travel direction
