Jason Roberts
Natural Disasters
Mr. Simmons
11/25/2012
2011 Tohoku Japan Earthquake & Tsunami
Report
According to Japan Quake Facts, the 2011 Tohoku earthquake and tsunami was a 9.0
magnitude mega thrust earthquake. This is the fourth largest earthquake in the world, and the
largest in Japan since instrumental recordings began in 1900. The earthquake happened off the
coast of Japan, at 14:46 JST, on Friday March 11th 2011. The epicenter — Earth’s surface above
the focus of an earthquake — was 130 kilometers (81 miles) off the east coast of the Oshika
Peninsula of Tohoku near Sendai. The hypocenter — the focus of an earthquake — occurred at a
depth of 32 kilometers (19.9 miles).
The MCEER Earthquake Engineering to Extreme Events reported that at least 15,690
people have been killed, and the death toll is expected to rise. However, Japan Quake Facts is
reporting a slightly different death toll: with 5,692 deaths, 2,409 injured and 9,522 people still
missing (this article was written one week after the earthquake and tsunami).
Some of the damage reported included extensive and severe structural damage, including
heavy damage to roads and railways as well as fires in many areas, and a dam collapse.
Approximately 4.4 million households in northeastern Japan were left without electricity and 1.5
million without water. The event shook buildings and damaged infrastructure hundreds of
kilometers away. Closer to the main shock, coastal regions were devastated both by the quake,
and the resulting tsunami.
According to NASA Earth Observatory the earthquake was originally designated as a
magnitude 8.9, but was later revised upward to a magnitude 9.0. This map shows the epicenter of
the quake located East of Sendai. This map also shows the ground motion and shaking intensity
from the Earthquake at dozens of locations across Japan. Each circle represents an estimate of
shaking as recorded by the USGS, in conjunction with regional seismic networks. Shades of pale
yellow represent the lowest intensity and deep red represents the highest intensity. The ground
shaking data is overlaid on a map of population density provided by Oak Ridge National
Laboratory.
Looking at the map it appears that the shaking ran parallel to the offshore subduction
trench, with the intensity decreasing more from east to west, as opposed to north and south.
Ground motion also seems to be more intense in coastal and riverine areas, where settlements are
built on softer sediments and less bedrock (NASA, 2011)
Take note of the intensity of shaking even near Tokyo, well away from the epicenter; the
lack of a severe human toll in that metropolitan area is surely a testament to the nation’s
earthquake preparedness (NASA, 2011).
In the week following the main quake, Japan endured 262 aftershocks of at least
magnitude 5, according to Japanese Meteorological Agency. Forty-nine were magnitude 6 or
greater, and three were 7 or higher. The aftershocks were almost entirely offshore, in a zone
stretching about 500 kilometers (300 miles).
The magnitude 9.0 Tohoku quake in Japan resulted from thrust faulting on or near the
subduction zone plate boundary between the Pacific and North America plates. According to
Earthquake-Report, at the latitude of this earthquake the Pacific plate moves approximately
westwards with respect to the North America plate at a rate of 83 mm/year, and begins its
westward descent beneath Japan at the Japan Trench. Note that some authors divide this region
into several micro plates that together define the relative motions between the larger Pacific,
North America and Eurasia plates; these include the Okhotsk and Amur micro plates that are
respectively part of North America and Eurasia.
Information gathered from The National Oceanic and Atmospheric Administration
(NOAA) states that the result of such a massive earthquake was a colossal tsunami. This tsunami
caused tremendous local devastation. This was the deadliest tsunami since the 2004 magnitude
9.1 Sumatra quake and tsunami; which caused nearly 230,000 deaths, and $10 billion in damage.
This diagram illustrates the epicenter of the earthquake, and tsunami, by the red star. The
waves were the highest in the darker red colored areas, and as the color shades begin to shade to
yellow, then to blue the wave height decreases in most areas. With each hour passing, you’ll
notice the shade color lightens. Japan was hit the hardest with the waves exceeding 10 meters.
The Tohoku coastline is particularly vulnerable to tsunami waves because it has many
deep coastal embayments that amplify tsunami waves and cause great wave inundations.
The aftermath of this entire disaster included both a humanitarian crisis and massive
economic impacts. It immediately created over 300,000 refugees in the Tohoku region of Japan,
and lead to shortages in food, water, shelter, medicine and fuel for the survivors. A further
serious impact of the tsunami was the critical damage done to the Fukushima Daiichi Nuclear
Power Plant, resulting in severe radiation leaks and the prospect of a long-term health and
environmental hazard in need of an expensive cleanup.
While most scientists do not believe that earthquakes can be predicted, and reports of
earthquake precursor signals have been difficult to verify, a new study is underway to determine
if this quake had a precursor. According to the American Geophysical Union, Heki reports a
possible ionospheric precursor to the devastating magnitude 9 earthquake in Tohoku. Analyzing
data from the Japanese GPS network, he detected an increase in the total electron content (TEC)
in the ionosphere above the focal region of the earthquake beginning about 40 minutes before the
quake. The TEC enhancement reached about 8% above the background electron content. The
increase was the greatest above the earthquake epicenter.
According to USGS the March 11th earthquake was preceded by a series of large
foreshocks over the previous two days, beginning on March 9th with one magnitude 7.2 shake
approximately 40 kilometers from the epicenter of the March 11th and continuing with another
three earthquakes greater than magnitude 6 on the same day.
Luckily for Japan, if any country is able to cope with an earthquake of this scale, it is
Japan. As a country that accounts for a fifth of the world’s most powerful earthquakes, Japan is
in a constant state of readiness for the arrival of the “big one.” Every child knows instinctively
what to do when the earth starts to shake, and people who are at home know to go to their front
door and open it, in case they need to make a quick escape.
Those who find themselves trapped in a modern upper floor of an office or apartment
building know that the buildings will sway violently, but are designed to stay upright during the
shaking.
According to The Guardian modern buildings – and Japan’s addiction to concrete means
most tall buildings are very modern – are built with deep foundations, the most advanced
supported by shock absorbers that allow the structure to move with the earth, rather than against
it.
“Even so, had the earthquake not been so far off the coast of Japan, the damage to the
country could have been even more severe,” said Kanoa Koyanagi, a geophysicist at the Pacific
Tsunami Warning Centre in Hawaii.
“Very fortunately it was a good distance off shore. If that happened right under the city it
would be a major problem. Anything above a magnitude eight under even a modern metropolitan
city is going to be a major problem,” Koyanagi said.
Analysis
The great magnitude 9.0 earthquake and tsunami of March 11th 2011, in Tohoku Japan
was not something that could have been predicted, at least of that magnitude. While there were 4
large foreshocks, one being of magnitude 7.2, followed by 3 greater than 6.0, there was no way
of knowing that those were foreshocks, and not aftershocks of the 7.2 previous quake.
Richard M. Allen, from the department of Earth & Planetary Science, in the
seismological laboratory writes: In October 2007 Japan turned on the first publicly available
nationwide earthquake early warning system; on March 11th 2011 it had its first true test during
the magnitude 9 Tohoku earthquake off the coast of Sendai. The system issued a warning before
the S-wave arrived onshore, a great achievement for the seismological community in Japan
(Allen).
The table below shows the real time estimates of the earthquake source parameters and
the maximum shaking intensity generated by the warning system. The warning was issued at
update number 4, 8.6 seconds after the first P-wave detection.
The map to the right shows
the amount of warning time when
the first warning was issued. The
contours are time until the S-wave
arrival in seconds. The region
within the 0 sec contour is the
blind zone where no warning is
available. The figure shows that
the warning was issued before the
S-wave reached the coastline.
From what I’ve learned about this disaster, the people of Japan were as prepared as they
could have been. Casualties could have been much more severe, and the amount of monetary
loss could have been much greater, if the people of Japan had not constantly been preparing for a
large event like this.
This disaster was linked to the physical environment of the ocean. Because it happened in
the ocean, a massive tsunami was created that put the entire Pacific Ocean coastlines on warning.
Also Tohoku’s coastlines are extremely vulnerable to tsunamis as they have deep embayments.
However; they were still extremely lucky that the epicenter was not directly below a major
metropolitan area. With the earthquake being so distant off the coast, they had sufficient time to
use their warning system.
Human activity did not make anything worse in this disaster, excluding the evident issues
with the Fukushima Daiichi Nuclear Power Plant; which is now the largest nuclear disaster since
the Chernobyl disaster of 1986. This could have been avoided if the cooling reactors would have
been flooded with salt water, prior to the overheating of the reactor. However due to the high
cost of the reactors this decision was put off until it was already too late.
The damage that was done via the earthquake and tsunami could have been much worse
30-50 years ago. Civilians would have been less prepared as we’ve only started keeping record
and monitoring quakes since 1900. There also would be no source of warning; I imagine a
scenario similar to that of Sumatra’s quake in 2004.
I feel that continuing education on earthquake preparedness, and tsunami preparedness
will prove to be invaluable. We need to continue development of ways to forecast earthquakes,
and possibly predict them in the future. Mitigation for this event was strong, but now looking
back at this disaster, it always could use adjustments to become even stronger.
In a situation like this, trying to find the positive proves to be difficult; of course it could
have been dramatically worse, if so many weren’t so prepared. Also with the tsunami waters
bringing in rich nutrients for the soil, this will be a positive mark for the country.
According to Business Insider, another positive factor is the announcement by Governor
Masaki Shirakawa of the Bank of Japan that he is ready to unleash “massive” liquidity to assure
the stability of Japan’s financial system and to meet the credit needs of the affected region.
Monday the 14th, the Bank of Japan followed through with an $85-billion injection into the
markets. Also, Prime Minister Kan indicated the government is preparing a major fiscal package.
While increased government outlays will add to the country’s excessive debt, this longer-term
consideration will not deter the government from taking action needed to meet this crisis.
Reflection
I really enjoyed being a part of this class. It taught me many new things about the world I
live in, that I never really understood. It forced me to look beyond just the text, and find the
answers to the questions I never would have had prior to being here.
My favorite class lecture was about astrological disasters. Learning about major
catastrophes, and extinction proved very frightening, yet intriguing. I couldn’t wait to go home
and show my family my newly found knowledge of crater impact locations, the difference
between meteors, meteorites, comets, and asteroids.
Living in Salt Lake City, with the Wasatch fault line so close to home, I enjoyed learning
about earthquakes. I was excited to write this paper on Japan’s disaster, just to learn more about
what might (cross my fingers that it doesn’t) happen here.
The only real issues I had with this class are the tests. They seemed to not test on your
knowledge of the material, but more on your attention to reading the actual question. There were
many trick questions that should have been avoided. So make sure if you take this class, you take
longer reading the question than is really necessary.
All in all, I would recommend this class to a friend.
Works Cited
Allen, R. M. (n.d.). THE MARCH 11, 2011 TOHOKU-OKI, JAPAN EARTHQUAKE. Retrieved
November 25, 2012, from http://seismo.berkeley.edu:
http://seismo.berkeley.edu/~rallen/research/WarningsInJapan/
American Geophysical Union. (2011, November 8). An ionospheric precursor to the Tohoku
earthquake. Retrieved November 25, 2012, from http://www.agu.org:
http://www.agu.org/pubs/crossref/2011/2011EO450010.shtml
Business Insider. (2011, March 14). The Real Economic Impact Of Japan’s Earthquake.
Retrieved November 25, 2012, from http://www.businessinsider.com:
http://articles.businessinsider.com/2011-03-14/markets/30084545_1_kobe-quake-kobeearthquake-massive-earthquake
Earthquake - Report. (2011, March 18). Understanding the M 9.0 massive Tohoku, Sendai,
Japan earthquake and tsunami. Retrieved November 25, 2012, from http://earthquakereport.com: http://earthquake-report.com/2011/03/18/understanding-the-m-9-0-massivetohoku-sendai-japan-earthquake-and-tsunami/
Japan Quake Facts. (2011, March 18). 2011 Japan Earthquake in Sendai Tohoku - Overview.
Retrieved November 25, 2012, from http://www.japanquakefacts.com:
http://www.japanquakefacts.com/articles/0/0/post/2011_japan_earthquake_in_sendai_toh
oku
Japanese Meteorological Agency. (2011, March 18). The 2011 off the Pacific coast of Tohoku
Earthquake. Retrieved March 18, 2011, from JMA:
http://www.jma.go.jp/jma/en/2011_Earthquake.html
MCEER. (2012). MCEER Earthquake Engineering to Extreme Events. Retrieved November 25,
2012, from http://www.mceer.com:
http://mceer.buffalo.edu/infoservice/disasters/Honshu-Japan-Earthquake-Tsunami2011.asp
Nasa Earth Observatory. (2011, March 11). Tohoku Earthquake Shaking Intensity. Retrieved
November 25, 2012, from Nasa Earth Observatory:
http://www.earthobservatory.nasa.gov/IOTD/view.php?id=49719
NOAA. (n.d.). Great Tohoku, Japan Earthquake and Tsunami, 11 March 2011. Retrieved
November 2012, 2012, from http://www.ngdc.noaa.gov:
http://www.ngdc.noaa.gov/hazard/honshu_11mar2011.shtml
The Guardian. (2011, March 11). Japan's earthquake preparation has spared it from a far worse
fate. Retrieved November 25, 2012, from http://www.guardian.co.uk:
http://www.guardian.co.uk/world/2011/mar/11/japan-earthquake-preparation
USGS. (n.d.). Poster of the Great Tohoku Earthquake (northeast Honshu, Japan) of March 11,
2011 - Magnitude 9.0. Retrieved November 25, 2012, from http://earthquake.usgs.gov:
http://earthquake.usgs.gov/earthquakes/eqarchives/poster/2011/20110311.php