ScienceScienceDo Now: 12-10Do Now: 12-10

HW: COMPLETE THE QUESTIONS FROM HW: COMPLETE THE QUESTIONS FROM TODAY’S NOTESTODAY’S NOTES

1.1. Stack your grade report if it needs to be Stack your grade report if it needs to be turned in today.turned in today.

2.2. Stack your Do Now sheets for collectionStack your Do Now sheets for collection3.3. Open text book to page 230Open text book to page 230TodayToday~ Power Point w/notes: Measuring ~ Power Point w/notes: Measuring

EarthquakesEarthquakes

Measuring EarthquakesMeasuring Earthquakes

Did you hear about any Did you hear about any earthquakes that occurred today?earthquakes that occurred today?

USGS- EARTHQUAKE INFORMATIONUSGS- EARTHQUAKE INFORMATION

Locating EarthquakesLocating Earthquakes

Seismic waves are Seismic waves are detected at detected at seismographic seismographic stations located stations located around the world around the world

They are located They are located at or near the at or near the Earth’s surfaceEarth’s surface

How does a seismograph work?How does a seismograph work?

Seismograph: records ground movements Seismograph: records ground movements of earthquakesof earthquakes

The pendulum sits still while the rotating The pendulum sits still while the rotating drum and ground moves.drum and ground moves.

Seismogram showsSeismogram shows the earthquakethe earthquake motion.motion.

Where is the center of an Where is the center of an earthquake?earthquake?

Focus: Point where rocks break Focus: Point where rocks break UNDERGROUNDUNDERGROUND

Epicenter: Center of earthquake ABOVE Epicenter: Center of earthquake ABOVE GROUNDGROUND

The S-P MethodThe S-P MethodLocating an EpicenterLocating an Epicenter

Distance to the epicenter is measured on aDistance to the epicenter is measured on a time-distance graph.time-distance graph. It takes THREE seismograph stations to locate It takes THREE seismograph stations to locate

an epicenter. A circle is drawn around each an epicenter. A circle is drawn around each location. The epicenter is where the 3 circles location. The epicenter is where the 3 circles overlap.overlap.

Epicenters from 1977 - 1996Epicenters from 1977 - 1996

Earthquake ScalesEarthquake Scales There are two There are two

different scales different scales used to measure used to measure earthquakes:earthquakes:

1.1. The Richter The Richter Magnitude ScaleMagnitude Scale

2.2. The Modified The Modified Mercalli Intensity Mercalli Intensity ScaleScale

The Richter ScaleThe Richter Scale Measures the amount of ground motion.Measures the amount of ground motion. Ranks from 1-10Ranks from 1-10 Each 1 point jump increases the ground motion 10 Each 1 point jump increases the ground motion 10

times!!times!! Measured using a seismographMeasured using a seismograph

Magnitude Estimated effects

2.0 can be detected only by seismograph

3.0 can be felt at epicenter 4.0 can be felt by most people in the

area 5.0 causes damage at epicenter 6.0 can cause widespread damage 7.0 can cause great, widespread damage

The Mercalli ScaleThe Mercalli Scale

Ranks from 1-12 with Ranks from 1-12 with Roman NumeralsRoman Numerals

Measures the Measures the intensity which = intensity which =

DAMAGEDAMAGE One Earthquake can One Earthquake can

have more than one have more than one intensity levelintensity level

What are the worst earthquakes What are the worst earthquakes ever recorded?ever recorded?