Earthquakes

EARTHQUAKES

By: Lauren Showers

EDU 290 Tu/Th 11:00am

WHAT IS AN EARTHQUAKE?

Merriam-Webster Dictionary defines an

earthquake as a shaking or trembling of the

earth that is volcanic or tectonic in origin.

http://questgarden.com/71/26/9/081013095448/

HOW DO EARTHQUAKES OCCUR?

Earthquakes occur when two blocks of land

suddenly slip past each other along a fault

line(USGS).

The location in which the earthquake starts is

called the Hypocenter. The location directly

above the hypocenter on the earth’s surface

is called the Epicenter (USGS).

HOW DO EARTHQUAKES OCCUR CONT.

jclahr.com

WHERE DO EARTHQUAKES OCCUR

Earthquakes occur along fault lines. There are

three major types of fault lines.

Strike-slip Faults

Normal Faults

Reverse Faults

STRIKE-SLIP FAULTS

Occur along transform boundaries

The two blocks of land move sideways past

each other on a horizontal plane (Plate-

tectonics.org).

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STRIKE-SLIP FAULTS CONT.

Famous strike slip faults include the San

Andreas fault in California and the Alpine

Fault in New Zealand.

Geology.com

NORMAL FAULTS

Occur at divergent plate boundaries.

The rocks on one side of the normal fault

moves downward against the rocks on the

other side (plate-tectonics.org).

REVERSE FAULTS

Reverse faults occur at convergent boundaries.

The rocks on one side of a reverse fault moves

upward. This movement of rocks at reverse faults

often causes earthquakes (plate-tectonics.org).

claremontgeography12.blogspot.co

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HOW ARE EARTHQUAKES MEASURED?

The Richter Scale is used to measure

earthquake magnitude.

On a 1-10 scale. 1 being the smallest, 10

being the largest.

Measured with a device called a

Seismograph.

aggas2nd.blogspot.com

TYPES OF WAVES

There are two types of waves associated

with earthquakes.

P-Waves

S-waves

TYPES OF WAVES CONT.

P-waves- Travel through solid rock and

liquids.

As it spreads out, it alternately pushes

(compresses) and pulls (dilates) the rock

(allshookup.org).

web.ics.purdue.edu

TYPES OF WAVES CONT.

Slower than P-waves

Can only move through solid rock.

As an S wave propagates, it shears the rock

sideways at right angles to the direction of travel

(allshookup.org).

web.ics.purdue.edu

AFTERSHOCKS

Smaller earthquakes that occur after the

main earthquake.

Aftershocks can last for weeks or months

after an earthquake.

The larger the main earthquake, the longer

aftershocks will continue to occur(usgs.gov).

PROTECTING YOURSELF IN AN EARTHQUAKE

“Drop, cover, and hold on!”

Drop down to your knees

Cover your head and neck

Hold on to a sturdy structure

(earthquakecountry.info).

REFERENCES

http://www.merriam-webster.com/dictionary/earthquake

http://earthquake.usgs.gov/learn/kids/eqscience.php

http://www.plate-tectonics.org/earthquakes/types-of-

faults.html

http://allshookup.org/quakes/wavetype.htm

http://earthquakecountry.info/dropcoverholdon/