Could It Happen Here? The prospect of a tsunami in the north west

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Could It Happen Here?The prospect of a tsunami
in the north west

• Joshua Alcantara
• Maria Dougherty

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Outline

• History of Previous Tsunamis
• What causes a tsunami?
• Types of Tsunamis
• Why Southern California?
• Other information
• Economic effect of a Tsunami.

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Area of possible tsunami in California
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History

• Southern California has been free of damaging
  earthquakes for the past 200 years.
• However, moderate earthquakes have been
  increasing recently
• Unusual damaging waves have gather considerable
  attention.
• Papua New Guinea July 17, 1998
• Also several locally generated tsunamis have been
  recorded.
• Santa Barbara December 1812 generated a tsunami
  effecting 60km (37.28 miles) of the coast.

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What Causes a Tsunami?

• Earthquakes with magnitudes less than 7.0 have
  been known to cause tsunamis.
• Scientists hypothesis potential tsunamis in
  southern California may be caused by submarine
  landslides, or slope failure.
• Two basic types of submarine landslides.
• Rupture Surface. (More likely to happen in
  California)
• Displaced Mass of Material.

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Rotational Slump

• Rupture surface cuts through a homogenous
  material
• Scoop shaped, concave upward
• Slope follows a circular arc.

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Translational Slide

• Rupture surface is planar
• Failure result of a heterogeneous material
• Bedding planes

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http//www.geocities.co.jp/SilkRoad-Ocean/4668/gal
lery/gallery.html
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http//www.geocities.co.jp/SilkRoad-Ocean/4668/gal
lery/gallery.html
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Why California?

• Slopes offshore of Southern California have thick
  accumulations of under-consolidated sediment.
• Studies have shown significant sliding and
  slumping recently.
• especially in the Santa Barbra Channel.
• Therefore underwater slope failures are easily
  triggard by seismic activity due to the low shear
  strength of the sediments, possibly giving give
  rise to a 20m tsunami.
• The deep basins, towering ranges, and canyons
  with steep walls that make up the southern
  California landscape can become immensely flooded
  

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Map of Southern California Coast
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Potential Wave Heights
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Speed of propagating wave
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Calculating the cost of a flood in Southern
California

• Southern California Planning Model a holistic
  approach to tsunami effects
• A model that incorporates the economic loss
  through loss of labor, transportation, services
• SPCM 1
• Shows detailed economic effects by region
• Trip matrices
• A model that traces back consumption patterns.
• Examples Journey to work and journey to services
• SPCM 2
• The model calculates direct losses within a
  damage area and the economic effects of those
  losses.
• Transportation effects on supply and demand

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Losses

• Direct losses Losses due to lost opportunities
  to produce.
• transportation issues
• Indirect and induced losses arise as people and
  businesses are unable to work or generate income
  as a result of the damages.
• Indirect losses Losses by suppliers whose
  products and services are no longer purchased by
  damaged firms and households.
• Induced losses Losses due to labor.

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Scenarios of flooded area
Direct, indirect and induced business loss in flooded area No freeway links Port of Los Angeles and Long Beach Closed reduction in export capabilities
Scenario 1
Scenario 2
Scenario 3 Truck and rail only
Scenario 4
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Questions?
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• Resources
• Jose Borrero, Ph.D., Sungbin Cho, James E. Moore
  II, Ph.D., Harry W. Richardson, and Costas
  Synolakis, Ph.D., Could it happen Here?
  American Society of Civil Engineers (2005)
  54-65,133
• http//www.geocities.co.jp/SilkRoad-Ocean/4668/gal
  lery/gallery.html
• http//www.noaanews.noaa.gov/stories2005/s2365.htm
  
• http//www.atlasmousepads.com/smiley-02.gif