Earthquakes

Earthquakes- Vibrations produced by movement at a fault.

Where do earthquakes happen?

Plate Tectonics

Sliding past one another - transform boundary Running into one another - convergent boundary Moving away from one another - divergent boundary

Fault- A break in the rock along which movement occurs. Types of faults Normal fault Reverse or thrust fault Strike-slip fault

Normal Fault- When tension pulls rocks apart, causing one side to fall down in relation to the other side.*

Normal Fault

Normal Fault near Death Valley

Reverse or Thrust Fault- Compression forces rocks above the fault up and over the rocks below the fault surface.*

Reverse or Thrust Fault

Thrust or Reverse Faults

Strike-Slip Fault- Transform or shear pressures cause rocks on either side of the fault to slide past each other.*

Strike-Slip Fault

Strike-slip Fault

Focus- The point where the rocks break. Epicenter- The point on the surface directly above the focus.

Types of Waves P-waves S-waves Surface waves

Primary Wave (P)- Fastest moving seismic wave Primary Wave (P)- Fastest moving seismic wave. Travels through solids, liquids, and gases.*

Secondary Wave (S)- Second fastest wave Secondary Wave (S)- Second fastest wave. Can travel through solids, not liquids.

Surface Wave (L)- The slowest wave. They cause the most damage.*

Moho- The boundary between the crust and the mantle where seismic waves speed up.*

Magnitude- A measure of the energy released by an earthquake as measured on the Richter Scale, which goes from 1 (weakest) to 10 (strongest).

Seismograph- Instrument used to measure earthquake magnitude.*

Wasatch Fault from Space

The Wasatch Fault at Provo UT

The San Andreas Fault This is a map view of the san andreas fault which is a strike-slip fault. Pressure builds up along this fault line and is released as one side slides past the other side.

Cypress Freeway Collapse

Crack opened up during the Earthquake.

The 1906 San Francisco Quake

1906 Earthquake Cont.

1906 earthquake damage and refugee camps

The Great Alaskan Earthquake This quake occurred on Good Friday in 1964. It was a magnitude 9.2, and the 2nd largest earthquake ever recorded. It is the largest earthquake recorded in North America.

The Great Alaskan Quake-Shaking continued for 4 minutes.

Great Alaskan Quake Cont.

Big Bear Earthquake, CA. Magnitude 6.4, June 1992.

Hyogo-Ken Naubu Earthquake Earthquake occurred in Japan on January 17, 1995. This freeway toppled over during the quake.

Liquefaction- Water is shaken to the surface and the soil becomes unstable.

Liquefaction Liquefaction occurs during an earthquake. Dirt particles line up and compact, allowing water to rise to the surface. The surface can turn into liquid mud. Heavy things sink, light things rise.

Effects of Liquefaction

Liquefaction in Kobe, Japan-1995.

Liquefaction in Kobe, cont.

Tsunami- An ocean wave generated by an earthquake.