TSUNAMI

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TSUNAMI
BASIC INFO 1.) Tsunami are NOT tidal waves, they
have nothing to do with tides 2.) They are
caused by BIG SPLASHES from earthquake
motion (Fig. 10-14) landslides extra
terrestrial impacts. http//esminfo.prenhall.com/s
cience/geoanimations/animations/86_Tsunami.html

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TSUNAMI SPEEDS
1.) velocity(square root of gravity) x (ocean
depth) g9.8m/sec2 depth for Pacific5500meters
on average so, velocity 232meters/sec518miles
per hour SMOKIN 2.) Because of friction with
bottom they slow down considerably but still hit
the shore at freeway speeds.
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TSUNAMI WAVE PROPERTIES
Lets compare to wind-blown waves Period Wave
length Wind blown 10 sec. 156 meters(130
ft.) Tsunami 3,600(60min.) 837,000 meters(520
miles)
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TSUNAMIS AT THE SHORELINE
1.) Misconception it is the height of the wave
that does the damage 2.) Is it like Deep
Impact NO-VIDEO of Deep Impact 3.) The shore
first recedes in response to movement.
Credit V.Gusiakov, 2005, Novosibirsk
Tsunami Laboratory
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TSUNAMIS AT THE SHORELINE (continued)
4.) The crest then propagates toward shore. 5.)
Low amplitude (meters-tens of meter) long
wavelength 6.) Hits the shore like a rapidly
rising tide. 4.) Recall the period about 60
minutes. 5.) This means as the water rushes
inland for about 30 minutes before
withdrawing AND CREATING ANOTHER SURGE VIDEO-
http//www.cbsnews.com/elements/2004/12/27/world/v
ideoarchive663162.shtml
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TSUNAMI CASE HISTORIES
ALASKA April 1, 1964 1.) Tectonic
Setting-Subduction-convergent 2.) 2 different
events occurred 3.) 20 min. after the 2nd a 30m
tsunami approached Scotch Gap Lighthouse. 4.)
Scotch Gap Lighthouse sat 14 meters above mean
low-water level.
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TSUNAMI CASE HISTORIES
ALASKA April 1, 1964 Scotch Gap Lighthouse sat
14 meters above mean low-water level.
Photo Courtesy of NOAA
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TSUNAMI CASE HISTORIES
ALASKA April 1, 1964 Hilo, Hawaii results 1.)
Raced across the Pacific at speeds up
to485m/h 2.) Hit Hilo at about 35 m/h 3.) Fastest
sprinter doesnt run 25m/h 4.) killed 159 people.
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TSUNAMI CASE HISTORIES
Papua New Guinea July 17, 1998 1.)
7.1magnitude 2.) Sounds like distant thunder
where heard 3.) pulled back and 4-5 min.
later. 4.) 4m (13ft.) Surge approached 5.)
second wave approached14m(45ft) 6.) 2,200
fatalities. 7.) VERY low topography?
Photograph by H. Davies Courtesy NOAA
Photograph by Fr Z Mlak. Courtesy of NOAA
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TSUNAMI CASE HISTORIES
Indian Ocean Dec. 26, 2004
Courtesy USGS
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TSUNAMI CASE HISTORIES
Indian Ocean Dec. 26, 2004
1.) Moment magnitude9.0 Pretty BIG 2.) 283,000
killed, 1.2 million displaced 3.) 8.4 billion,
with Indonesia suffering the bulk of that at
5.4 billion.
Refuge Camp Credit Livescience.com
Incoming wave crest Credit Livescience.com
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LANDSLIDE GENERATED TSUNAMI SEICHE
July 9, 1958 largest historic rock fall
Lituya Bay Alaska (lots o action in
Alaska) On the opposite side of bay 520 ft
up forest was stripped Lake Tahoe Tectonic
Setting active,subparallel faults tensional
system 3-4 change of mag. 7 in next 50
years is this a real concern? Evidence? (ND
pg. 93/fig. 3.43)
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TSUNAMI WARNING SYSTEM
Deep-ocean Assessment and Reporting of
Tsunamis (D.A.R.T.)
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TSUNAMI WARNING SYSTEM
Systems placed in areas with history of tsunami
generation
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