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. Originates from _________________

◦________________________________: 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 Originates from _________________

__________________ 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 Originates from _______________

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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.

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◦ RICHTER 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, Missouri, and Maine◦ 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◦ 1800’s to present: San

Andreas Fault: transform-fault (strike-slip) boundary

◦ 1811-1812 New Madrid: three blind faults found deep inside the crust (Craton Boundary)