Earthquake Destruction and Dangers

Earthquake Destructionand Dangers

http://embc.gov.bc.ca/em/hazard_preparedness/earthquake_photos.html

Major causes of earthquake damage

• Landslides and liquefaction • Aftershocks• Tsunamis

Landslides

• Movement of material down a slope, especially…– on steep slopes – when saturated land is shaken violently

Liquefaction

• Loosely packed soil turns into mud.

• Most likely to occur in soil saturated with water.

Liquefactionanimation

Aftershocks

• Smaller earthquakes that occur after a larger earthquake in the same area

• They can occur hours, days, or months later

• Buildings already weakened by the original earthquake can topple during aftershocks

Tsunami • A wave set off by an

underwater earthquake• Earthquake jolts the ocean

floor; pushes water out of the way

• Displaced water forms large waves (tsunamis)– In the open ocean, height of

wave is not significant– As the wave gets closer to

land, water gets more shallow, pushes up into a tall wall ≈100 ft

YouTube:CBS News

Asian Tsunami

YouTube:Tsunami Animation

http://news.nationalgeographic.com/news/2011/03/pictures/110315-nuclear-reactor-japan-tsunami-earthquake-world-photos-meltdown/#/japan-earthquake-tsunami-nuclear-unforgettable-pictures-wave_33291_600x450.jpg

http://www.dailymail.co.uk/news/article-1366395/Japan-tsunami-earthquake-Rescuers-pick-way-apocalypse-wasteland.html

How do we prepare?• Base-isolated buildings

–Buildings rest on shock absorbing springs that allow the building to move without violently shaking

Protecting Structures

How do we prepare?• Base-isolated buildings

–Buildings rest on shock absorbing springs that allow the building to move without violently shaking

• Warning systems– Monitoring faults and waves

Instruments for monitoring faults

• Creep meter – measures HORIZONTAL movement along

a fault line through movement of a wire across the fault

• Tiltmeter– measures VERTICAL movement, works

like a carpenter’s level

• Satellites – Measure VERTICAL changes in the

distance between the satellite and ground

Faults & Earthquakes

Fault monitoring instruments

Creep meter Tiltmeter

Instruments for monitoring tsunamis

• Tsunami detection buoys – 39 stations collect seafloor height,

temperature, pressure

• Warning centers– If a tsunami is generated, they issue

advisories, watches and warnings

Summary!

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