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Earthquake Destruction and 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 - PowerPoint PPT Presentation
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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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