1. Aim: How are Earthquakes Measured?
Introduction: Some seismic events are stronger and do more damage than others. The most violent earthquake in modern times was probably a 1960 event centered in the Pacific Ocean off the coast of Chile. But this earthquake did not have the human toll of two earthquakes that occurred in China, one in 1556 and the other in During these earthquakes, buildings were destroyed and hundreds of thousands of people died.

2. I. Earthquake Scales
Seismologist use two different methods to measure earthquakes.

3. A. Mercalli Scale
Based on the reports of people who felt the earthquake and observed the damage it caused.

4. Problems with Mercalli Scale
Based on the picture above, hypothesize the Mercalli rating for this earthquake.

5. B. Richter Scale
Based on measurements made with an instrument called a seismograph.
It is more precise because it is based on measurement with a tool.
It is a LOGARITHMIC scale- an increase in one unit translates to a 10-fold increase in the quantity measured.

6. Seismograph

7. Richter Scale Richter Magnitude TNT Energy Equivalent Example 1.0
6 ounces
Construction site blast
1.5
2 pounds
WWII Conventional bombs
2.0
13 pounds
Late WWII Conventional bomb
2.5
63 pounds
WWII Blockbuster bomb
3.0
397 pounds
Massive Ordnance Air Blast Bomb
3.5
1,000 pounds
Chernobyl Nuclear Disaster 1986
4.0
6 tons
Small Atomic Bomb
4.5
32 tons
Average Tornado
5.0
199 tons
Nagasaki Atomic Bomb
5.5
500 tons
Massena, NY 1994
6.0
6,270 tons
Double Spring Flat, NV 1994
6.5
31,550 tons
Coalinga, CA 1983
7.0
199,000 tons
Hebgen Lake, MT 1959
7.5
1,000,000 tons
Landers, CA 1992
8.0
6,270,000 tons
San Francisco, CA 1906
8.5
31,550,000 tons
Anchorage, AK 1964
9.0
199,999,000 tons
2004 Indian Ocean Earthquake

8. THE END!