21 April 2016 Tsunamis Coastal Erosion Sea Level Change Rebecca Clotts Department of Geology, University of St Thomas

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http://www.palomar.edu/oceanography/salty_ocean.htm
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Coastal Hazard: Tsunamis • Wave caused by the vertical displacement of ocean water • Requires a Trigger 4

What triggers tsunamis?
EARTHQUAKES Rapid uplift or subsidence of the sea floor http://www.tsunami.noaa.gov/tsunami_story.html
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What triggers tsunamis?
LANDSLIDES Lituya Bay, Alaska 6

30.5 million cubic meters of rock fell into ocean 7

Bay water surged to 1790 ft (524 m) above normal 8

What triggers tsunamis?
VOLCANOES 9

40 m (140 ft) Tsunami 10

What triggers tsunamis?
ASTEROIDS 11

Preliminary evidence of 66 ft high tsunami waves in NYC 12

Killer Tsunamis Source: Wikipedia

http://nctr.pmel.noaa.gov/database_devel.html
https://www.youtube.com/watch?v=_4zKS10oo_Y&feature=youtu.be
Most Recent: 2 March 2016 15

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Where will Tsunamis occur?

What are the effects of Tsunamis?
Primary effects of
flooding
and
erosion
– Shorten the coastline – Debris erodes both landscape and human structures Secondary effects – Fires – Contaminated water supplies – Disease

How is the tsunami hazard minimized?
Detection and warning – Monitor earthquake zones (seismographs) – Tsunami warning system • Tidal gauges to determine sea level changes • Buoy sensors to detect tsunami in open ocean ( http://nctr.pmel.noaa.gov/Dart/Jpg/DART II_05x.swf
) Pacific Tsunami Warning Center: http://ptwc.weather.gov/

How is the tsunami hazard minimized?

How is the tsunami hazard minimized?
• Structural control – Building codes for susceptible coastline areas • Land use – Native vegetation may provide defense – Development of land must be monitored • Probability analysis • Education

How is the tsunami hazard minimized?
• Signs of a Tsunami • If you feel an earthquake, leave the beach or low-lying area.
• If you see the ocean receding, run from beach.
• A small tsunami in one location may be larger nearby.
• If you hear the tsunami siren, move to higher ground.
• Do NOT go down to the beach to watch the tsunami. If you can see it, you are already in danger.

Coastal Hazard: Coastal Erosion 23

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How does Coastal Erosion happen?
Animation: http://www.learnnc.org/lp/multimedia/14706 Movie: https://www.youtube.com/watch?v=U9EhVa4MmEs (2 mins) 25

How fast?
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Where does Coastal Erosion occur?
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How is Coastal Erosion mitigated?
http://www.msstate.edu/dept/geosciences/CT/TIG/WEBSITES/RESEARCH/Gregory_Harris/index.htm
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How is Coastal Erosion mitigated?
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Coastal Hazard: Sea Level Change 30

What is sea level change?
RELATIVE NOAA Sea Levels Trends: http://tidesandcurrents.noaa.gov/sltrends/sltrends.html
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What is sea level change?
GLOBAL 32 Graph from NOAA

What causes sea level change?
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What causes sea level change?
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What causes sea level change?
3. Changes in the rate of sea floor spreading 35

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How does this apply to YOU?!
But… Minnesota has 44,926 miles of shoreline (source MN DNR)

University of Minnesota Extension – Shoreline Education: http://www.extension.umn.edu/environment/shoreland/ 39

Not exactly…
In Lake Erie: • 1844 - 22 ft seiche killed 78 people, dammed ice blocking Niagara Falls • 2008 – Winds created waves up to 16’ and flooded Buffalo NY 40

No.
The data in this graph originated from the U.S. Army Corps of Engineers-Detroit District Lake Level Data available through the MN DNR at: http://www.dnr.state.mn.us/climate/wat erlevels/lakes/index.html
41 http://files.dnr.state.mn.us/waters/area_hydros.pdf