EARTHQUAKES AND WAVESEnergy Transformation in the form of Seismic Waves

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What do you know about Earthquakes?

Earthquakes

• Earthquakes transfer stored energy into kinetic energy in form of seismic waves.

• These waves are MECHANICAL waves• Waves are an oscillation or vibration that transfers energy

Earthquake Identification and Location

• Earthquakes are located and identified by their focus, epicenter and magnitude

• Focus: The point where the fracture in rock occurs, (under ground).

• Epicenter: The point, on land, directly above the focus point.

• Magnitude: The amount of energy or destruction that has been released/caused

Seismographs

Seismographs

•Explain the difference between a Focus and an Epicenter?

•If earthquakes are mechanical waves, what are the other types of waves called?

Magnitude

1. Richter Scale: Measures the total amount of energy released by the earthquake.

• Magnitude 7 or greater is a major quake• Magnitude 6 or less is a minor quake• Magnitude 2 or less is a micro quake or tremor

Magnitude Continued

•2. Mercalli Scale: Measures the degree of destruction that has been caused. This is a scale that is far more subjective in nature.

Mercalli scale rates on a scale of I – XII

(I) is little damage and (XII) is extreme destruction

Seismic Waves

Primary or P waves

• Fastest moving seismic wave

• Arrive at recording stations first

• Moves in a spring like way

• Travel through both liquid and solid material

Secondary or S waves

• Slower moving wave• Arrives at recording

stations after the P wave

• Moves in an up and down way

• Cause buildings to shake

• Travels through solid material only

Primary and Secondary Waves

• P waves oscillate through compression and expansion, in the same direction of movement

• S waves oscillate in a direction that is perpendicular to direction of movement

L-Waves

• L waves are also known as surface waves

• They are the slowest but most destructive waves

• They are the waves that cause surface rolling

•Which is the fastest moving seismic wave?

•Which seismic wave is most destructive?

Distance to Epicenter• Seismologists determine the distance to the earthquake’s

epicenter through analyzing the difference in arrival times at the recording station.

• When arrival times are close, with little difference, the distance to the epicenter is very small.

• The greater the difference in arrival times, the further away the epicenter is

• Use information from 3 recording stations to triangulate the location

Triangulation

Location of Earthquakes

• 3 major locations where earthquakes occur

Ring of Fire

Earthquake location continued

Mid ocean ridges

Earthquake locations continued

The Eurasian-Melanesian Mountain Belt

What is the different plate activity at each of the locations where seismic activity takes place?Ring of Fire, Mid-Ocean Ridge,and Eurasian-MelanesianMountain Range