1. Section 3: Earthquakes and Society
Chapter 12 – Earthquakes
Section 3: Earthquakes and Society

2. Section 3 Objectives
Discuss the relationship between tsunamis and earthquakes
Describe two possible effects of a major earthquake on a building
List three safety techniques to prevent injury caused by earthquake activity
Identify four methods scientists use to forecast earthquake risks

3. TSUNAMIS!!! Giant ocean waves that form after Volcanic eruptions
Submarine earthquakes
Underwater landslides

4. Destruction to Buildings and Property
Amount of earthquake damage to buildings depends on several factors
Structure of buildings –
Weak walls that are not constructed to withstand swaying motion of ground
Very tall buildings may sway and topple over, damaging the buildings around them
Building foundations
Loose soil and rock is more likely to be damaged than solid ground
Liquefaction

5. Earthquake Safety Before After During
Supplies of food, water, batteries, flashlights, and radio
Have emergency earthquake drill plans in place ( how to turn off gas, water, and electricity)
During
Stay calm and move to a safe position inside along the inner walls. Stay away from objects that may fall or topple over.
After
Be cautious, check for fire and other hazards. Wear shoes near broken glass. Avoid downed powerlines and any other wires.
People who live near active faults should follow these rules to prevent death, injury, and property damage

6. Earthquake Warnings & Forecasts
Unpredictable
Scientists can use past earthquakes to predict where more earthquakes might occur, but cannot predict when the might occur
Seismic gap – area of a known fault that hasn’t had an earthquake in awhile, but has the potential for a large, violent earthquake
Foreshocks can precede a larger earthquake by a few seconds or weeks. Not always an efficient warning system

7. Changing Rocks & Seismic Gaps
Measurements of slight tilting of the ground, areas of strain and cracks, and gas seepage are used to monitor areas for potential seismic activity
Scientists hope to use this information to one day better predict major earthquakes in order to save lives and reduce property damage