# Lesson 13 Magnitude and Intensity Reading

```Name: _______________________________________ Date: ____________________ Period: ____________________
Read “Magnitude & Intensity” on pg. 159-163, then answer the following questions:
1. What is the name of the scale used to measure magnitude? The Richter Scale
2. What does the scale measure? (be specific, don’t just say magnitude)
The total amount of energy released at the source of the earthquake.
3. How do scientists determine the magnitude of an earthquake?
Scientists measure the amplitude (how high the peaks go) of the waves on the seismogram and use that measure
to calculate magnitude.
4. What does each increase on the magnitude scale represent? (i.e. what is the difference between a 5.0 and a 6.0)
The amplitude is ten times greater for each increase in magnitude. A magnitude 6 earthquake has amplitude that
is ten times higher than a magnitude 5 earthquake.
5. What is the name of the intensity scale used to measure earthquakes? Modified Mercalli Scale
6. What does the intensity scale measure/describe?
The effect on people, structures and the environment.
7. What factors affect the intensity of an earthquake?
The distance from the epicenter, the depth of the earthquake, the population density of the area, the local
geology, the type of building and how long the earthquake lasts (duration) all affect the measured intensity of the
earthquake.
8. Read both of the scales on pg. 160 and 161. How many minor earthquakes happen each day? Major earthquakes
per year?
9,000 very minor earthquakes happen per day, but only about 18 major earthquakes are recorded each year on
average.
9. Look at the two pictures on pg 163. Based on the pictures, what intensity levels would you say caused the damage