Earthquakes; Rock Cycle Flashcards
scale of a earthquake
log factor 10
how can we tell how much energy is generated in an earthquake?
- fractures
- how it moves
What is the Mercalli scale?
- not about the magnitude of energy released
- not good
What are P-waves
- compressional waves (like sound)
- faster
- primary
What are S-waves
- transverse waves
- up and down
- do not go through fluids
- shear stress
- secondary
what is a surface wave?
- motion does not depend upon distance from surface
- the same everywhere
- circular wave
- motion decreases as you go down (wave base)
- ocean
What is wave base?
the bigger they are the less they are
where do earthquakes occur?
- plate boundaries
- mid-ocean ridge
how do earthquakes feel at mid-ocean ridges?
shallow
what is liquid faction?
- things turned to liquid when shaken
- sedimentary basements
- stiff at first
what happens when an earthquake is in the ocean?
- water cannot support shear stress
- water displaced with surface waves (one plate goes up and the other down)
- wavelength decreases when wave base touches the floor
when do waves break
1:7 ratio
isostemic
bounds of weight
- ocean crust getting older and denser
failed rift
what can earthquakes do?
tell us about the interior of the Earth
which layer has more volume?
mantle
what is epicenter?
surface impact
what is focus?
depth
- subduction zones
dense rocks
faster seismic waves
what is the Mohorovicic discontinuity?
- crust and mantle
- different properties
What are shadow zones?
where do waves refract?
- angle
internal reflection
deeper= higher pressure = faster
- ROGH
what is seismic tomography?
what can we do to forecast earthquakes in the short term?
-
what can we do to forecast earthquakes in the long term?
- stress relief
- stress relocated
how does mountain building work?
what happens when you build mountains
- deform crust
- orogen
what happens when you deform a rock quickly?
returns to its original shape
what does inelastically mean?
when you deform a rock slowly over a long time, so it does not come back
what is a normal fault
tension hanging wall moves down relative to foot wall
what is a thrust fault
to pieces of a rock override each other
- not so angled
what is a strike-slip?
what is strike and dip?
strike: horizontal line that touches surface of dip: steepest like perpendicular to strike
what is an anticline?
dome of hill
(old rock)
what is a syncline?
dip of hill
(young rock)
