1. Earthquake Damage Can Be Reduced
2.3 Notes
Earthquake Damage Can Be Reduced

2. Earthquakes can cause severe damage and loss of life
Each year, there is about one earthquake with a magnitude of 8 or higher-this is an extremely powerful earthquake. UM
Earthquakes can cause severe damage and loss of life

3. Earthquakes can cause severe damage and loss of life
8.0 earthquakes (or bigger) can destroy all buildings near their epicenters and cause huge loss of life.
9.0 Earthquake in Japan in lasted 6 minutes and killed 18,000 people.
Earthquakes can cause severe damage and loss of life

4. Earthquakes can cause severe damage and loss of life
Most deaths from earthquakes are caused by collapsing buildings and fires, not by the shaking of the ground.
Earthquakes can cause severe damage and loss of life

5. The most powerful earthquakes can release more energy than 1 million weak earthquakes combined!
Earthquake magnitude is described using a number scale from 0-10 (no real maximum possible value).
Earthquake magnitude

6. The first number scale was developed in the 1930’s by Charles Richter and Beno Gutenberg.
Describes an earthquake’s magnitude based on how fast the ground moves at a seismic station.
Earthquake magnitude

7. Most scientists today prefer the moment magnitude scale (MMS), which measures the total amount of energy released by an earthquake.
Earthquake magnitude

8. Both the Richter Scale and the MMS increase by 32 times with each whole number increase.
A magnitude 5 earthquake is 32 times stronger than a magnitude 4 earthquake.
A magnitude 6 earthquake is times stronger than a magnitude 4 earthquake!
Earthquake magnitude

9. The MMS is more accurate and also allows scientists to measure the strength of earthquakes that occurred before seismographs were invented by measuring the strengths of rocks and length they moved along a fault.
Earthquake magnitude

10. Damage from earthquakes
Earthquakes can crack roads, buildings, damns, and any other structures that exist on top of a fault.
Damage from earthquakes

11. Damage from earthquakes
Earthquakes can also raise, lower, or tilt the ground surface.
Damage from earthquakes

12. Damage from earthquakes
An aftershock is a smaller earthquake that follows a more powerful earthquake in the same area.
Sometimes aftershocks cause buildings that were weakened by an initial earthquake to collapse.
Damage from earthquakes

13. Damage from earthquakes
Fire caused by earthquakes can cause significant damage.
In the 1906 San Francisco Earthquake, fire caused more than 90% of the damage.
Damage from earthquakes

14. Damage from earthquakes
Landslides are a common side effect of earthquakes as soil is shaken loose.
Liquefaction is a process in which shaking of the ground causes soil to temporarily act like a liquid.
Damage from earthquakes

15. Damage from earthquakes
Liquefaction can cause structures to sink down into the soil or flow away with it.
Damage from earthquakes

16. A tsunami is a water wave triggered by an earthquake, volcanic eruption, or landslide.
Tsunamis can be taller than a 20-story building!
Damage from tsunamis

17. A tsunami may be a single wave but can also be several waves that have different heights and arrive hours apart.
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Damage from tsunamis

18. In deep water, tsunamis can travel at 700 km/hr (430 mi/hr)!
As tsunamis approach coastlines, they slow down and grow in height.
Damage from tsunamis

19. In 2004, an earthquake off the coast of Sumatra caused a tsunami.
280,000 people died.
Damage from tsunamis

20. Scientists work to monitor and predict earthquakes
We cannot predict the day or even year that an earthquake will occur.
Sometimes there are signs and sometimes there are none at all.
Scientists work to monitor and predict earthquakes

21. Scientists work to monitor and predict earthquakes
Long term predictions can be generated.
Example: An area might have a 60% chance of being hit by an earthquake with magnitude 7 or higher in the next 25 years.
Scientists work to monitor and predict earthquakes

22. Scientists work to monitor and predict earthquakes
Scientists around the world work constantly to try to better predict earthquakes, by observing the following things:
Tilts or changes in the elevation of the ground
Slow movements or stretching in rock
The development of small cracks in the ground
Scientists work to monitor and predict earthquakes

23. Structures can be designed to resist earthquake damage
For safety during an earthquake, the best place to be is outside and away form any buildings.
Structures can be built to withstand strong ground shaking. I
Structures can be designed to resist earthquake damage

24. Structures can be designed to resist earthquake damage
Scientists make maps of areas that have many earthquakes.
Planners use these maps to develop rules for building in these areas.
Structures can be designed to resist earthquake damage

25. Structures can be designed to resist earthquake damage
For small buildings (like houses):
Should be firmly fastened to the foundation
Should have strong walls
Structures can be designed to resist earthquake damage

26. Structures can be designed to resist earthquake damage
For large buildings (like skyscrapers):
Base isolators: flexible material between building and foundation
Cross braces: X shaped braces added to a building to help a building keep its shape.
Structures can be designed to resist earthquake damage

27. review The moment magnitude scale is based on the
Amount of ground movement at a seismic station
Amount of building damage caused by an earthquake
Number of human deaths caused by an earthquake
Amount of energy released by an earthquake
review

28. review 2. One method of making a building earthquake resistant is to
Add sand under the foundation
Reduce the use of steel
Make the walls of brick
Use cross braces
review