Announcements

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Announcements

• Want more geology?
• Try these courses next quarter
• Geo 204, Geology and Society (Monsters)
• Geo 211, Physical Geology (for majors or advanced
  others)
• Geo 214, Environmental Geology
• Geo 309, Volcanology

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Todays Plan

• Current Events
• Finish with Quake Prediction
• Long-term
• Short-term?
• Elastic Rebound Theory
• Types of seismic waves
• Measuring quake location magnitude

3
EQ Prediction

• Two time scales
• long term (decades to centuries)
• short term (hours/days/years)
• Long term predictions based on seismic gaps
• Turkey example
• prediction in 1997 (12 in next 30 yr)
• Ismet EQ (M7.4) in August 1999

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Long Term Prediction
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Long Term Prediction
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Long Term Prediction
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Ismet 3m strike-slip offset
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Ismet damage and deaths
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Short Term Prediction

• Relies on recognition of precursors
• land deformation
• increased seismic activity
• geomagnetic and geoelectric changes(affects
  animal behavior?)
• groundwater level changes
• None works!

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Short-term predictions

• Parkfield, CA
• M6 quakes every 22 years

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Parkfield EQ prediction project

• Between creeping and locked sections of the SAFZ

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Parkfield EQ prediction project

• Tons of instruments waiting since 1985 for next
  M6
• (Expected by 1993)
• ...still waiting...

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How do quakes happen?

• Elastic Rebound Theory
• Stress builds up
• until it exceeds the friction along a fault
  surface
• (or breaks rock, forming a new fault surface)

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Elastic Rebound Theory

• Winch and Brick Demonstration (version 1.0)

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Earthquake Waves

• Several different kinds generated by every
  earthquake (e.g. P, S, surface)
• Differ in terms of particle motion

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Earthquake Waves

• Different wave motion allows us to determine
  material properties (e.g. the outer core is
  liquid (no S waves!))
• Student wave demo
• Different wave speeds (e.g. P faster than S)
  allow location by triangulation

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Waves Damage

• Nerf balls springs demo
• Different frequencies match different building
  sizes/structures
• Can tune buildings to resonate at frequencies
  other than those likely from quakes

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Measuring Quakes

• Location
• Magnitude

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Algeria Seismograph (Idaho)
P-wave arrives in Idaho (1857 UTC)
Quake occurs (1844 UTC)
S-wave arrives (1908 UTC)
Surface wave arrives (1924 UTC)
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Elastic Rebound Theory

• Brick Demonstration (version 2.0)

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Quick check

• In the brick and winch demo, the cranking winch
  represents
• The movement of tectonic plates
• The stretching of the silly putty
• The strain released during an earthquake
• The steady build up of stress in the rocks

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Quick check

• In the brick and winch demo, the stretching
  bungee represents
• The movement of tectonic plates
• The stretching of the silly putty
• The strain released during an earthquake
• The steady build up of stress in the rocks