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Chapter 5 Lesson 3 Objectives:
1. Explain where most Earthquakes in the U.S. occur
2. Describe how scientists measure Earthquakes
3. List ways to make your classroom and home more earthquake safe.
Rough Outline I. Earthquake Activity A. Studying Earthquakes B. Measuring Earthquake Magnitude C. Past Earthquakes D. Describing Earthquake Intensity E. Liquefaction F. Tsunamis G. Tsunamis Warnings II. Earthquake Safety A. Quake resistant Structure B. Before an Earthquake C. During an Earthquake D. After an Earthquake
I. Earthquake Activity
Earthquakes are used to study the inside of Earth
A. Studying Earthquakes Seismologists: scientists who study
earthquakes.
B. Measuring Earthquakes Magnitude
Magnitude: Measure of the energy released during an earthquake
The Richter Scale: • Scale used to describe the strength of an
earthquake • Has no upper limit – 9.5 would be about the
highest • For each increase of 1.0 the height of the line on
a seismogram is 10x greater or 32 times as much energy is released.
C. Past Earthquakes
1999 – Turkey - 7.8
1556 Shensi, China
1906 – San Francisco Cal.- 8.3
1975 Laoning Province, China – 7.5
First, the water level in a pond inexplicably plunged. Then, thousands of toads appeared on streets in a nearby province. Finally, just hours before China's worst earthquake in three decades, animals at a local zoo began acting strangely.
1990 IRAN 7.7
2001 INDIA 7.7
2003 North Algeria 6.8
2010 Haiti 7.0 (over 300,000)
2010 Chili 8.2
D. Describing Earthquake Intensity
Modified Mercalli Scale: Measure the amount of damage they cause.
Damage depends on: 1. Strength of
earthquake 2. Surface material 3. Design of structures 4. Distance from
epicenter
E. Liquefaction
Occurs when wet soil acts more like a liquid during an earthquake.
Causes buildings to sink into the soil and collapse
F. Tsunamis
Ocean waves caused by earthquakes
G. Tsunami Warnings
1. Water along the shoreline might move rapidly toward the sea, exposing a large portion of land that normally is underwater.
2. Pacific Warning System near Hawaii predicts arrival times
II. Earthquake Safety 1. Don’t live in an area prone to earthquakes
A. Quake-Resistant Structures
In new buildings: Seismic-safe structures: Structures with rubber bands around then
area more likely to withstand the “earthquake.”
In older buildings Installation of steel rods to reinforce building
walls
B. Before an Earthquake
1. Move heavy objects to lower shelves 2. To reduce fires make sure all water
heaters and other gas appliances are secured
3. Placing sensors on gas lines
C. During an Earthquake
Indoors 1. Move away from windows 2. Seek shelter in doorways or under tables
Outdoors 1. Stay in the open away from power lines 2. Stay away from buildings
D. After an Earthquake
1. Shut off any gas lines 2. If you don’t know how to shut lines leave
immediately 3. Call 911 4. Stay away from damaged buildings 5. Be careful of broken glass – wear sturdy
boots 6. Stay away from beaches