1. Earthquake Destruction & Dangers

2. The major causes of earthquake damage
Soil conditions
Liquefaction
Landslides
Aftershocks
Tsunamis

3. Soil Conditions
Layers of loosely packed soil, high in moisture can lead to
Liquefaction
Landslides

4. Liquefaction Loosely packed soil turns into mud.
Most likely to occur in soil saturated with water.

5. YouTube:
Liquefaction
Demo

6. Landslides Can occur… when filled land is shaken violently.
where steep slopes are found.
YouTube:
Landslides

9. Aftershocks
An earthquake that occurs after a larger earthquake in the same area.
They can occur hours, days, or even months later.
Buildings already weak from the original earthquake can topple due to aftershocks.

11. How do we prepare for earthquake damage?
Base-isolated buildings
Buildings designed to absorb energy from earthquakes.
Rest on shock absorbing springs which cause the building to move back and forth without violently shaking.

13. Protecting Structures

14. Tsunamis
Earthquake jolts the ocean floor, it pushes water out of the way.
This displaced water forms large waves called tsunamis.
In the open ocean, the height of the tsunami wave is not high at all.
As the wave gets closer to land and the water gets shallower, it pushes up into a tall wall of about 30 meters (100 ft).
YouTube:
Anatomy of a
Tsunami
YouTube:
How do tsunamis
Relate to Earthquakes

19. Hawaii Tsunami
Tsunamis

20. Monitoring Faults

21. Instruments for short-range predictions
creep meter
laser-ranging
tiltmeter
satellites

22. Creep meter
measures HORIZONTAL movement along a fault line. (Transform boundary – strike-slip fault)
a wire is placed across the fault
it is attached to a weight that can slide if the fault moves.
Geologists measure how much the weight has moved.
Faults & Earthquakes

23. Laser-ranging device measures HORIZONTAL movement.
The laser is on one side of the fault and a reflector is on the other side of the fault.
Any change in the time needed for the laser beam to travel across to the reflector and back indicates fault movement.
The more time it takes, the farther the reflector is getting as the fault moves.

24. Tiltmeter measures VERTICAL movement
It consists of two bulbs that are filled with a fluid and connected by a hollow tube.
If the land rises or falls, fluid will flow from one bulb to the other.
Each bulb contains a scale to measure the depth of the fluid.

25. Satellite monitoring A satellite measures VERTICAL movement.
It bounces waves off the ground and back into space measuring the distance between the satellite and the ground.
If the distance from the satellite to the ground changes, then geologists can detect changes in elevation.
YouTube:
Rising
Himalayas

26. Why can’t scientists predict the exact time and place an earthquake is going to occur?
Even though a fault can be monitored, it is still impossible for geologists to know exactly WHERE on the fault the stress will be released.