1. Measuring and Locating Earthquakes

2. Bellringer 11/5
Put these Roman Numerals in order from least to greatest:
lX, Vll, lll, Xl, lV, l, XV

3. Make a notes section: Title it “Locating Earthquakes.”

4. Magnitude Energy produced by earthquake Amplitude = Height of wave
Richter Scale = numerical rating system used to measure the magnitude of an earthquake

5. Richter Scale Numbers are determined by amplitude
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

6. Richter scale

7. 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

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

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

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

12. 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

13. Adding data from other stations narrows area of focus
Three 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 2 points
3 circles 1 point = EPICENTER

14. Epicenter

15. Seismic Belts
seismic belts - separate large regions of little or no seismic activity. It’s where majority of Earthquakes occur.

16. Most correspond closely with plate boundaries
80% along Circum-Pacific Belt
Subduction zone