Earthquake hazards

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Earthquake hazards

• Ground Rupture

Alaskan pipe after the Denali quake ruptured
through
Ground rupture from the M8.1 2001 Tibet earthquake
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Earthquake hazards (cont.)

• Shaking
• Wave amplitude
• Wave frequency
• Duration of shaking

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Earthquake hazards (cont)

• Liquefaction
• Saturated sand loses strength upon shaking

• Tsunami
• Wave wavelength ocean waves that can travel vast
  distances

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Sumatra Earthquake tsunami
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Seismic Hazard of MA
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Cape Ann Earthquake 1755
Woodcut illustration depicting damage in Boston
from the earthquake
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Hazard vs risk

• 1989 Macquarie Ridge, New Zealand
• M 8.3
• No losses
• 1960 Agadir, Morocco
• M 5.5
• 12,000 deaths

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Earthquake Risk

• Risk hazard x vulnerability
• The amount of damage and numbers of earthquake
  related deaths do not correlate to magnitude of
  the earthquake.

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Products of hazard assessment

• Active fault map
• Historical seismicity
• Earthquake likelihood

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3D models assess seismic hazard in Los Angeles, CA
SCEC Community Fault Model
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Acceptable Risk

• Level of acceptable risk depends on the structure
• Cannot design for maximum earthquake with low
  probability
• Social question

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How would you mitigate damages from.

• Ground Rupture
• Liquefaction
• Ground Shaking
• Tsunami

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Ground Rupture

• Avoid construction
• Relocate sensitive facilities
• Implement low use facilities
• Playing fields
• Green space

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Portola Valley California
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Liquefaction

• Recognize liquefaction potential
• In-situ remediation
• Avoid construction in liquefaction prone areas

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Tsunami mitigation

• Early warning system
• Broadcast signal to beaches after a major
  earthquake anywhere in the ocean basin
• Saftey guidelines
• Go to high ground
• Climb a tree

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Ground Shaking

• Recognize the degree of probable ground shaking
  in the area
• Improve construction methods to accommodate
  shaking without collapse