December 26, 2004
The Sumatra
Earthquake &
Tsunami
Nick D’Anna
Plainedge Schools
Great Wave off the Coast of Kanagawa, by Hokusai
This print is somewhat misleading in that tsunamis
do not always manifest themselves as the huge
breaking waves.
What is a tsunami?
• From the Japanese word tsunami meaning
"harbor wave“
• Often mistakenly called "tidal waves“.
• They have nothing to do with tidal action.
• Seismic sea waves caused by
earthquakes, submarine landslides, and,
infrequently, by eruptions of island
volcanoes.
Deep Earthquakes occur at subduction zones
Tsunami waves
are sent out
radially from the
point of thrust. A
tsunami wave can
travel enormous
distances. The
Dec. 26th tsunami
eventually made
its way to the
pacific ocean and
noticeably
affected the sea on
the west coast of
the US.
• Most tsunamis do not result in giant breaking
waves.
• Rather, they come in much like very strong and
very fast tides (i.e., a rapid, local rise in sea
level).
• Much of the damage inflicted by tsunamis is
caused by strong currents and floating debris.
The Facts about December 26th
A great earthquake occurred at 00:58:50
(UTC), at 6:58 a.m. local time, on Sunday,
26 December 2004. The magnitude 9.0
event was located off the West coast of
Northern Sumatra.
This is the fourth largest earthquake in the
world since 1900 and is the largest since
the 1964 Prince William Sound, Alaska
earthquake. The earthquake had a depth
of 10 km
X
Page 5 of your ESRT
At Sumatra, the Indian
plate was subducted
beneath the overriding
Burma plate. The
Indian plate begins its
decent into the mantle
at the Sundra trench
(west of the epicenter).
The relative motion of
the two plates has been
6cm/yr.
Image curtsey of Eric Cohen
Historical Seismic Activity
Past Tsunamis
Indian Ocean
Tsunami
Natl. Inst. of
Advanced
Industrial
Science &
Technology
A section of the northern shore of Aceh, Sumatra,
Indonesia, pre- and post-tsunami (by Digital Globe)
A section of the northern shore of Aceh, Sumatra,
Indonesia, pre- and post-tsunami (by Digital Globe)
A section of the northern shore of Aceh, Sumatra,
Indonesia, pre- and post-tsunami (by Digital Globe)
Tsunami Warning Systems do exist.
Unfortunately, there was no such
system in place among the nations
around the Indian Ocean. Within
15 minutes of the megaquake,
officials from the PTWC were
calling nations in danger to warn
them. The information was slow to
get to the locations in greatest risk.
Tsunami Warnings
There are currently two tsunami warning
centers for Canada and the US:
1. The West Coast / Alaskan Tsunami
Warning Center (WC/ATWC)
2. The Pacific Tsunami Warning Center
(PTWC)
• Seismographs record Earthquake activity
world wide.
• Buoys in the ocean send signals to
satellites about the level of the sea
surface.
• That information is sent to the Tsunami
warning centers which in turn make
decisions about weather to issue a
warning.
• If a warning is issued, there are a few
ways to notify the public.
• Locally, sirens are used.
• For distant tsunamis, NOAA radio stations
notify the public
• The best immediate response is to head
for higher ground.
• Locations within 1 mile of the coast and at
elevations lower than 100 ft are at the
greatest risk.
Amateur video of the tsunami
A Sri Lanka resort
Another Sri Lanka resort
Phuket resort, Thailand
Patong beach, Thailand
Penang beach, Malaysia
Links for more information on this event
• www.NYTimes.com
• USGS Sundra Trench Earthquake and Aftershock Map at
http://www.oceansonline.com/sunda_trench_earthquake.
pdf
• Tectonic Summary of Sumatra Earthquake,
http://www.oceansonline.com/Tectonic%20Summary%20
USGS.pdf
• 2004 Indian Ocean Earthquake graphic
http://www.oceansonline.com/images/745pxHarta_Ocean_Indian_Quake.png
• Tsunami Great Waves,
http://www.oceansonline.com/great_waves_en_2002.pdf
• Dr. C’s Remarkable Ocean World
http://www.oceansonline.com/tsunami2004.htm
References
• Most of the diagrams and images from
this PowerPoint come from
GlobalSecurity.org at
http://www.globalsecurity.org/eye/andam
an-ani.htm
• The video clips are courtesy of Steve
Kluge, Earth Science Teacher.