Chapter 12Earthquakes Name: __________________ Period: _______ Date: ______________
_____________: a crack or break along the surface of the earth where movement is detected • _________________: caused by tension (pulling apart) • _________________: caused by compression (pushing together) • _________________:horizontal movement on both sides of the fault (moving in different directions)
____________________: A shaking of the earths crust caused by a sudden release of energy. • Causes of earthquakes • ____________________________ • ____________________________ • ____________________________ • ____________________________ • ____________________________
Depth of earthquakes • Depth depends of plate location of earthquake • Can occur between ____ and ______ km in earth
________: the fault plane where an earthquake occur (inside the earth) • _____________: the point of the surface of the earth where the earthquake occurs. It’s directly above the focus.
____________________________________: • Compression waves (like accordion) • Fastest moving: 6KM/SEC • Can travel through all material (solid, liquid, or gas) • Used to locate epicenter and map interior of earth.
________________________________: • Shearing action (side-to-side) • Can only travel through solids • Half as fast as the Primary wave: 3KM/SEC • Used to map in the interior of the earth. • Used to locate epicenter
__________________ wave comprising the actions of the primary and secondary wave • Composed of Love and Rayleigh Waves • Felt at the surface • Most destructive wave • Slowest moving wave: 1KM/SEC
Primary Waves: “P” waves travels the fastest, 6km/s, compression action (like accordion) on rock; travel through all materials; originates from focus. Secondary Waves: “S” waves travel at 3 km/s; shearing action (move rock at right angles of wave direction of movement), only move through solids; originates from focus. “L” wave is a combination of the Rayleigh and Love wave, travels at 1km/s; originates at epicenter, most destructive wave. XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
P and S wave velocities • Used to map the interior of the earth • When hits new material, wave velocity and direction change • At about 2900 km, velocity changes, Secondary waves stop: Outer Core Boundary • Waves hit a boundary at 8 to 32 km: Mohorovicic’s Discontinuity (boundary of the crust and mantle)
_____________________: • Due to velocity and direction changes of the Primary and Secondary waves, an area of the earth will not register an earthquake. This area is between 102 and 143 degrees from the epicenter. The Shadow Zone in dependent on the location of the earthquake (it moves with each earthquake).
_______________________: • Detects and records earthquakes • Different types of seismographs for each wave • Wave action recorded on a ____________________
Determining the distance to the earthquake epicenter • Using the time and distance traveled by Primary and Secondary waves • Use a time-travel graph to find distance to epicenter
Location the epicenter • Need __________ locations to locate epicenter. • Distance is radiated around station • Where circles intersect, that is where the epicenter is located.
Earthquake strength measured several ways • RICTER SCALE (1940’s): amount of energy released by quake. • Each number is 32x stronger than the number below • Example: Magnitude 5 is thirty-two times stronger than magnitude 4 quake • _________________________: accounts for power and type of area that the quake happened • _________________________: accounts for the amount of damage caused by the earthquake
Earthquake risk and prediction • In the US, California is not the only place of earthquake risk • Alaska, Hawaii, Washington, Oregon, Montana, Idaho, and Missouri • A successful prediction will have: when, where, strength, and duration. • Prediction Hints: tilting of the ground, increased radon emissions in wells, change in velocity of P-wave,
____________________ • When an earthquake happens in the ocean, the release of the quake causes giant tidal waves to radiate out is all directions. This wave’s height increases as it approaches land
Examples of Famous Earthquakes • 1964: Alaska: subduction boundary earthquake • 1989-1992: San Andreas Fault: transform-fault (strike-slip) boundary • 1811-1812 New Madrid: three blind faults found deep inside the crust (Craton Boundary)