1. 2/24/15 To-Do ► Get your 19.3 notes out and have them ready. ► We’re going to investigate possible Mercalli Intensity values for different pictures. We’ll then map out an epicenter using Mercalli Intensity values. ► HS-ESS1-2. ► I can compare and contrast earthquake magnitude and intensity and the scales used to measure each.

2. 19.3 – Measuring and Locating Earthquakes

3. Magnitude ► Magnitude = a measure of energy produced by earthquake ► Amplitude = Height of wave ► Richter Scale = numerical rating system used to measure the magnitude of an earthquake

4. Richter Scale ► Numbers are determined by amplitude of largest seismic wave ► Each successive number represent an increase in amplitude of a factor of 10 ► Example: Magnitude-8 is 10x larger than magnitude-7  Energy difference is even greater, = 32x

5. Richter scale http://www.maelor-humanities.org.uk/GCSEhum/Resources/PP-photos/pp-KeyIss3/Richter.scale.jpg

6. Moment Magnitude Scale ► Rating scale that measures the energy released by an earthquake taking into account the size of the fault rupture, the amount of movement, and the rock ’ s stillness ► Comparison with Richter:  New Madrid, MO 1812 - Richter scale 8.7 -- MMS 8.1  San Francisco, CA 1906 - Richter scale 8.3 -- MMS 7.7  Prince William, AK 1964 - Richter scale 8.4 -- MMS 9.2  Northridge, CA 1994 - Richter scale 6.4 -- MMS 6.7

7. Mercalli Scale ► Measures intensity of earthquake using Roman Numerals  Worse damage = higher numeral ► Intensity = amount of damage caused by earthquake

8. http://www.state.il.us/IEMA/images/Mercalli.jpg

9. Intensity ► Depends on amplitude of surface waves ► Surface waves decrease in size with increase distance from focus  Intensity decreases as well

10. Depth of Focus ► Shallow, Intermediate, Deep ► Shallow = catastrophic with high intensity  Produce greater maximum intensity than deep focus ► Deep = smaller vibrations

11. Locating Earthquakes ► Seismogram and Travel-time Curve allow scientists to determine distance to epicenter ► Seismogram records time elapsed between arrival of waves ► Distance is determined by measuring separation of waves on seismogram and identifying the same separation on Travel- Time curve

12. Locating Earthquakes Cont. ► Multiple seismograms are needed because one just determines certain distance in any direction  Circle is drawn around station with radius equal to distance ► Adding data from other stations narrows area of focus  2 circles overlap @ 2 points  3 circles overlap @ 1 point = EPICENTER

13. Epicenter http://wps.prenhall.com/wps/media/objects/3030/3102952/epicenter_tasa_shad.jpg

14. Seismic Belts ► Majority of Earthquakes occur along seismic belts that separate large regions of little or no seismic activity

15. ► Most correspond closely with plate boundaries ► 80% along Circum-Pacific Belt  Subduction zone http://upload.wikimedia.org/wikipedia/commons/thumb/0/09/Pacific_Ring_of_Fire.png/800px-Pacific_Ring_of_Fire.png

16. In-Class Assignment ► Get out a new sheet of paper! ► Mini Lab pg. 541 ► Ignore #1 ► Turn in Traced Map with labeled intensities, contour lines, and analysis question answers at the end of class