Could It Happen Here? The prospect of a tsunami in the north west Joshua Alcantara Maria Dougherty.
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Transcript of Could It Happen Here? The prospect of a tsunami in the north west Joshua Alcantara Maria Dougherty.
Outline
• History of Previous Tsunamis
• What causes a tsunami?
• Types of Tsunamis
• Why Southern California?
• Other information:– Economic effect of a Tsunami.
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.
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.
Rotational Slump
• Rupture surface cuts through a homogenous material
• Scoop shaped, concave upward
• Slope follows a circular arc.
Translational Slide
• Rupture surface is planar
• Failure result of a heterogeneous material– Bedding planes
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
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
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.
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 3Truck and rail only
Scenario 4
Scenarios of flooded area
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/gallery/gallery.html– http://www.noaanews.noaa.gov/stories2005/s2365.htm– http://www.atlasmousepads.com/smiley-02.gif