Transcript Document

(REUTERS)
Japan’s Earthquake
&Tsunami 2011
Magnitude 9.0 NEAR
THE EAST COAST
OF HONSHU, JAPAN
Friday, March 11,
2011 at 05:46:23
UTC
Images courtesy of the US Geological Survey
The earthquake
occurred 130
km (80 miles)
east of Sendai
and 373 km
(231 miles)
northeast of
Tokyo.
This is one of the largest earthquakes
that Japan has ever experienced.
In downtown Tokyo, large buildings shook violently. Elsewhere
severe flooding occurred due to a tsunami generated by the
earthquake.
Part of houses
swallowed by tsunami
burn in Sendai, Miyagi
Prefecture (state)
after Japan was
struck by a strong
earthquake off its
northeastern coast
Friday, March 11,
2011.
New York Times
The earthquake caused some damage –
but the tsunami was devastating
Tsunami waves
swept away
houses and cars in
northern Japan
and pushed ships
aground.
The tsunami waves
traveled far inland,
the wave of debris
racing across the
farmland, carrying
boats and houses
with it.
Fires after earthquakes are often caused by broken gas pipelines
CNN reported “The quake rattled
buildings and toppled cars off bridges
and into waters underneath. Waves of
debris flowed like lava across farmland,
pushing boats, houses and trailers
toward highways.”
A number of fires broke out including
one at an oil refinery which was burning
out of control.
Giant fireballs rise from a burning oil
refinery in Ichihara, Chiba Prefecture
(state) after Japan was struck by a
strong earthquake off its northeastern
coast Friday, March 11, 2011.
Los Angeles Times
 Let’s take a look at tsunami as it hits the
east coast of Japan
 http://www.bbc.co.uk/news/world-asiapacific-12725646
Globally, this is the 5th largest earthquake
since 1900 (or 4th depends on M).
Great (M > 8) Earthquakes Since 1900
9.6
Chile 1960
9.4
Alaska 1964
9.2
Sumatra 2004
Russia 1952
Magnitude
9
Japan 2011
8.8
Ecuador 1906
Chile 2010
Alaska 1965
8.6
8.4
8.2
Chile1906
8
7.8
1900
1920
1940
1960
Year
1980
2000
2020
What is a Tsunami?
(harbor wave)
Seismic sea waves (NOT tidal waves)
Large ocean wave or series of ocean waves
generated by an earthquake, volcanic eruption,
submarine landslide or meteor impact
How do EQs cause a tsunami?
http://sese.asu.edu/teacher-resources
http://geology.com/articles/tsunami-geology.shtml
Tsunami causes
 Unless there is an underwater landslide, strikeslip EQ WILL NOT cause tsunami
 Most tsunami generated by subduction zones
•






Chile
Alaska
Japan
Cascadia
Philippines
Caribbean
New Zealand
Tsunami wavelength and
speed
 Long wavelengths (over 100 km)
 Travel at high speeds : 450 to 650 mph
316,800 ft = 60 miles
Projected travel times for the arrival of
tsunami waves across the Pacific
Nearby the
earthquake there
are only minutes
to evacuate.
However, in many
other regions
there is advance
warning.
How long before
the tsunami
reaches Los
Angeles?
What happens when tsunami
gets near shore?
 Tsunami slows down (shallower water)
 Wave gets taller
Tsunami nears shore
 As wave gets into shallow water bottom of
wave drags along ocean floor
 Top of wave still moving fast: causes
cresting of wave, and breaking onto shore
Tsunami warning
 Receding of coastal waters ( 5 - 15 minutes before
the strike ).
 Approaching tsunamis are almost always
heralded by a noticeable fall of coastal
waters.
 Water may recede several hundreds of
meters. If you are on the beach, and you
see water suddenly receding, exposing
the ocean floor, it means that you have
minutes before the tsunami strikes.
 What do you do?
Run for high ground!
 Let’s take a look at what Japan looks like
before and after
 http://www.abc.net.au/news/specials/jap
an-quake-2011/
Detecting a tsunami
 Pressure recorder on
bottom of ocean
 Buoy to communicate
readings via satellite
 Tsunami Warning
Centers issue warning
Tsunami Warning Centers
 Hawaii and Alaska
 When EQ considered capable of
generating tsunami, send warning with
estimated arrival time
 Once tsunami hits
somewhere, tsunami
watch established to
monitor tide gauges
and ocean buoys
Tsunami Monitoring Systems
Locations of NOAA’s National Data Buoy Center (NDBC) DART stations comprising the operational network.
Tsunami Warning
 When warning is issued – low lying
areas are evacuated
 U.S. Coast guard issues warnings over
marine frequencies
 Some places have sirens