Section 12-2 ReviewSection 12-2 ReviewPage 304 (1-5)Page 304 (1-5)

#1#1

Describe the instrument that is used to Describe the instrument that is used to record seismic waves.record seismic waves.

A seismograph consists of three sensing A seismograph consists of three sensing devices that record ground motion: devices that record ground motion: one records vertical motion, one one records vertical motion, one records horizontal east-west motion, records horizontal east-west motion, and the third records horizontal north-and the third records horizontal north-south motion.south motion.

Seismographs through TimeSeismographs through Time

#2#2

Compare a seismograph and a seismogram.Compare a seismograph and a seismogram.

A seismograph is the sensing device. A seismograph is the sensing device. The seismogram is the tracing of The seismogram is the tracing of earthquake motion made by the earthquake motion made by the seismograph.seismograph.

SeismographSeismograph

SeismogramSeismogram

#3#3Summarize the method that scientists used Summarize the method that scientists used

to identify the location of an earthquake to identify the location of an earthquake

before computers became widely used.before computers became widely used.

Scientists drew circles on a map around Scientists drew circles on a map around three seismograph stations. They used three seismograph stations. They used the lag time between the arrival of the the lag time between the arrival of the P waves and the S waves to determine P waves and the S waves to determine the distance between each site and the the distance between each site and the epicenter. The epicenter was located epicenter. The epicenter was located where the three circles intersected.where the three circles intersected.

1000 2000 3000 4000 5000 6000 7000 8000 9000 10,000

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Distance from epicenter (km)

Earthquake P-wave and

S-wave Travel Time

“LAG TIME”

Locating the EpicenterLocating the Epicenter

#4#4Describe the scales that scientists use to Describe the scales that scientists use to

measure the magnitude of an earthquake.measure the magnitude of an earthquake.

Richter ScaleRichter Scale - determines earthquake - determines earthquake strength based on ground motion and strength based on ground motion and adjusts for distance.adjusts for distance.

Moment MagnitudeMoment Magnitude - measures earthquake - measures earthquake strength based on the size of the area of the strength based on the size of the area of the fault that moves, the average distance the fault that moves, the average distance the fault blocks move, and the rigidity of the fault blocks move, and the rigidity of the rocks in the fault zone.rocks in the fault zone.

Richter ScaleRichter Scale

Richter ScaleRichter Scale

Mercalli ScaleMercalli Scale – – the measure of the the measure of the intensity of an earthquake. Measure intensity of an earthquake. Measure from I to XII (12).from I to XII (12).

II – is not felt except by very few under – is not felt except by very few under especially favorable conditionsespecially favorable conditions

XIIXII – causes total destruction; distorts – causes total destruction; distorts lines of sight; objects are thrown into lines of sight; objects are thrown into the airthe air

Mercalli ScaleMercalli Scale

#5#5

Explain the difference between magnitude Explain the difference between magnitude

and intensity of an earthquake.and intensity of an earthquake.

Magnitude is the measure of an Magnitude is the measure of an earthquake’s strength. Intensity a earthquake’s strength. Intensity a measure of the effects of an measure of the effects of an earthquake on a particular area.earthquake on a particular area.

For example . . . For example . . .

Utah EarthquakeUtah Earthquake

MagnitudeMagnitude – 2.6 (Richter – 2.6 (Richter Scale)Scale)

IntensityIntensity – Depends on – Depends on distance from the epicenter.distance from the epicenter.

6. Summarize how 6. Summarize how energy is transferred energy is transferred between the sun and between the sun and

consumers in an consumers in an ecosystem.ecosystem.

Sun’s energy is stored in carbohydrates Sun’s energy is stored in carbohydrates (sugars and starch’s) produced by plants (sugars and starch’s) produced by plants during photosynthesis.during photosynthesis.

The energy is obtained by consumers that The energy is obtained by consumers that eat the plants.eat the plants.

Energy is transferred to other consumers Energy is transferred to other consumers that eat those consumers.that eat those consumers.

Energy from animal and plant remains is Energy from animal and plant remains is transferred to decomposers when they die.transferred to decomposers when they die.

The End????The End????http://www.seis.utah.edu/req2webdir/recenteqs/Quakes/quakes0.html