Chapter 5 Flashcards
Define: Earthquake
Earth shaking caused by rapid release of energy
Define: Focus (hypocenter)
The place where the fault slip occurs
Define: Epicenter
point on surface directly above the faults
Define: Fault
Fracture surface separating blocks of rock that have moved relative to one another
The blocks on a dipping fault are classified as the ____________ and the _____________________.
hanging wall
Footwall
In a normal fault in the crust, the hanging wall moves ________________ relative to the footwall.
down
A normal wall results from what kind of stress?
pull-apart or stretching (tension)
In a reverse fault, the hanging-wall moves _____________ relative to the footwall.
Up
A reverse fault results from what kind of stress?
Compression (squeezing or shortening)
In a strike-slip fault, one block slides past the other block while maintaining a relatively flat surface. What stress is this this the result of?
Shearing
Seismic waves are vibrational waves that travel via solid earth materials outward in all directions from the FOCUS. Name the 2 main groups of seismic waves.
- Body waves
- Surface waves
Define: body waves
Fastest waves that travel through the body of the earth
Define: Surface waves
Slower waves that travel along the earth’s surface, most destructive type of seismic waves
What two types of body waves are there?
Which one is the fastest?
- P-waves (fastest)
- S-waves
S-waves (secondary or shear waves) only travel through ______________.
Solids
What 2 type of surface waves are there?
- Love waves
- Rayleigh waves
What is a seismometer?
An instrument that an measure ground motion.
What 2 measurements describe earthquake size?
- Intensity: severity of damage
- Magnitude: amount of energy released by the earthquake
What does the Mercalli Scale measure?
Intensity
What is the magnitude of an earthquake?
QUANTITATIVE measurement of amount of energy released by an earthquake
Is the logarithmic richter scaled still in use today?
No
What is the most accurate measurement of the magnitude of an earthquake today?
Moment Scale
Intermediate and deep earthquakes only occur at what type of plate boundaries?
Convergent
True or False: The shearing San Andres fault is a very active strike-slip fault.
True
What likely cause are there for Intraplate Earthquakes?
Remnant crustal weaknesses in the former fault ones or ancient plate boundaries
Name 2 human activities that can cause earthquakes?
- Deep waste disposal
- Nuclear bomb/explosions
How do p-waves and s-waves cause earthquake damage?
P-waves: first to arrive, produce a rapid, buckling up and down motion
S-waves: arrive second, produce a pronounced back and forth motion
How do love waves and rayleigh waves affect earthquake damage?
Love waves: arrive soon after s-waves and cause ground to writhe like a snake
Rayleigh Waves: last to arrive and cause land surface to undulate like ripples across a pond. Theses waes usually last longer than the others.
Which of the 4 types of seismic waves cause the most damage?
Rayleigh waves
