TOHOKU EARTHQUAKE IN

JAPANBy Leah Bailas

WHAT IS AN EARTHQUAKE?

An earthquake is the result of two sections of the earth slipping by each other.

Different parts of an earthquake:

- Fault/Fault Plane: Area where the slip occurs.

- Hypocenter: Location beneath the earth’s surface where the earthquake originates.

- Epicenter: Location directly above the earthquake on the earth’s surface (Wald, 2012).

PARTS OF AN EARTHQUAKE

Image courtesy of USGS (http://earthquake.usgs.gov/learn/kids/eqscience.php)

JAPAN’S HISTORY OF EARTHQUAKES Japan has had a long and active history of earthquakes and general seismic activity. The earliest recorded earthquake in Japan occurred on November 26, 684. It was called the Hakuhou Nankai earthquake, and it had a magnitude of approximately 8.4 (Kawasumi, 1951, p. 477).

There are many different tectonic plates underneath Japan. As a result, there are more earthquakes due to these plates slipping against each other. Japan is located in the “Ring of Fire,” an area where many eruptions and earthquakes occur (Witze, 2012, p. 23).

RING OF FIRE Image courtesy of USGS (http://pubs.usgs.gov/gip/dynamic/fire.html)

THE FOURTH LARGEST FAULT SLIP EVER RECORDED On March 11, 2011, Japan experienced the fourth largest earthquake that has ever been recorded in the history of earthquakes. Tohoku, as it was called, had a magnitude of 9.0, and it paired up with a devastating tsunami. It was a large slip at such shallow depths, which is why there was so much damage in Japan. There were tsunami waves, flooding, landslides, fires, building and infrastructure damage, nuclear incidents, etc. More than 15,000 people died, over 6,000 were injured, and 2,651 went missing (Rajendran, Andrade, Thulasiraman, & Rajendran, 2011, p. 966).

THE START OF TOHOKU

Image courtesy of Snow Japan(http://www.snowjapan.com/the-great-east-japan-earthquake-11th-march-2011)

THE IMPORTANCE OF “MAGNITUDE”Magnitude is “a measure of the amount of energy released during an earthquake” (What is the "magnitude" of an earthquake?, 2012).

A seismograph can measure the motions of an earthquake, which helps to determine its size.

The closer the seismometer is to the earthquake, the larger the amplitude on the seismogram.

SEISMOGRAPH RECORDING OF

TOHOKUImage courtesy of ECGS(http://www.ecgs.lu/tohuko-kanto-mw9-japan/)

WHAT CAUSED TOHOKU?

The Tohoku earthquake fault was a complex puzzle. Although it was completely ruptured, some parts moved in different ways. The deeper parts shifted quickly, while the shallower parts shifted slowly. When the tension caused by subduction (the downward movement of plates shifting against each other) was released, the earthquake occurred. At the fault’s location, the two plates of the earth’s crust slid past each other up to 260 feet (Hashimoto, Noda, & Matsu'ura, 2012, pp. 2-4).

CROSS-SECTION OF TOHOKU FAULT

Image courtesy of LiveScience(http://www.livescience.com/27773-how-japan-s-2011-earthquake-happened-infographic.html)

GEOPHYSICAL EFFECTS OF TOHOKUTohoku moved portions of northeastern Japan closer to North America by as much as 2.4 meters (Chang, 2011).

Tohoku shifted the earth’s axis by estimates of between 10 cm and 25 cm (Chai, 2011).

Parts of Japan experienced soil liquefaction as a result of Tohoku (Chai, 2011).

The earthquake was so strong that it changed the earth’s rotation, making it 1.8 microseconds shorter (Gross, 2011).

SOIL LIQUEFACTION CAUSED BY TOHOKU

Image courtesy of Wikimedia Commons(http://commons.wikimedia.org/wiki/File:Soil-liquefaction_at_Shinkiba_after_2011_Tohoku_Pacific_Ocean_offshore_earthquake.jpg)

A VERY SLIPPERY FAULT

Recent studies have helped to explain the main reason behind Tohoku. Using data from Japan Trench Fast Drilling Project (JFAST), scientists have revealed that clay caused the low slip resistance (Baek, et al., 2012).

The combination of the clay material along the fault zone and the temperature made the fault very slippery. The particular layer in question contained smectite, which is known to become very runny (Baek, et al., 2012).

SMECTITE CLAY Image courtesy of BioStar(http://www.biostareq.com/newsletters/2012/01-January/biostar-newsletter-2012-01-January.html)

WHERE DID TOHOKU HIT?

Tohoku’s epicenter was approximately 70 kilometers east of the Oshika Peninsula of

Tohoku. But it did not only affect the epicenter – it affected the entire country of Japan, and

areas around Japan as well (Hashimoto, Noda, & Matsu'ura, 2012, p. 1).

AREAS AFFECTED BY TOHOKU

Image courtesy of USGS(http://mceer.buffalo.edu/infoservice/disasters/Honshu-Japan-Earthquake-Tsunami-2011.asp)

LAND SUBSIDENCE CAUSED BY TOHOKU The Geospatial Information Authority of Japan reported land subsidence from the Tohoku earthquake (Witze, 2012).

According to EcologyDictionary.org, land subsidence is “The sinking or settling of land to a lower level in response to various natural and man-caused factors.” An earthquake as strong as Tohoku has the ability to cause the land to sink inwards.

AN EXAMPLE OF LAND SUBSIDENCE IN

ARIZONAImage courtesy of ADWR(http://www.azwater.gov/AzDWR/Hydrology/Geophysics/)

AREAS WHERE LAND SUBSIDENCE

OCCURRED DURING TOHOKU

Information courtesy of Geospatial Information Authority of Japan(http://www.gsi.go.jp/ENGLISH/page_e30031.html)

Miyako, Iwate – 0.50 m (1.64 ft)Yamada, Iwate – 0.53 m (1.73 ft)Ōtsuchi, Iwate – 0.35 m (1.14 ft)Kamaishi, Iwate – 0.66 m (2.16 ft)Ōfunato, Iwate – 0.73 m (2.39 ft)Rikuzentakata, Iwate – 0.84 m (2.75 ft)Kesennuma, Miyagi – 0.74 m (2.42 ft)Minamisanriku, Miyagi – 0.69 m (2.26 ft)Oshika Peninsula, Miyagi – 1.2 m (3.93 ft)Ishinomaki, Miyagi – 0.78 m (2.55 ft)Higashimatsushima, Miyagi – 0.43 m (1.41 ft)Iwanuma, Miyagi – 0.47 m (1.54 ft)Sōma, Fukushima – 0.29 m (0.95 ft)

THE DAMAGING EFFECTS OF TOHOKU Tohoku caused a lot of damage to not only the land, but to the buildings and people that inhabited the land. Because there was also a tsunami that followed Tohoku, there was an increased amount of damage. Areas of Japan were being flooded, buildings were deteriorating, nuclear plants were at risk, and many lives were taken. Tohoku affected Japan’s entire ecosystem, and they are still recovering to this day (Stimpson, 2011, pp. 96-97).

A COMBINATION OF FIRES AND FLOODING IN JAPAN AFTER THE EARTHQUAKE

Image courtesy of Japan Society(http://www.japansociety.org.uk/earthquake/)

OTHER AREAS THAT WERE AFFECTEDUnited States: Parts of the U.S. (i.e. Hawaii, western part of Alaska, California coast, etc.) received many tsunami warnings from the National Tsunami Warning Center (Stimpson, 2011, p. 98).

South Pacific: Waves in the Philippines increasingly rose and some homes along the coast in Jayapura, Indonesia were destroyed. Papua New Guinea’s Boram hospital was hit by waves after evacuating patients (Stimpson, 2011, p. 98).

South America: Peru reported more than 300 homes damaged and Chile reported 200 homes damaged (Witze 2012).

TSUNAMI ALERTS IN VARIOUS AREAS

AROUND THE WORLD

Image courtesy of The Social Scientist(http://soksay.blogspot.com/2011/03/tsunami-slams-japan-after-89-magnitude.html)

AFTERSHOCKS

Tohoku was not the end of the unfortunate series of events in Japan. An earthquake with a magnitude of 7.3 hit Tohoku on the Saturday following the disaster. This earthquake also triggered a small Tsunami (Datta & Kamal, 2012, p. 792).

On April 7, 2011, there was a 7.1 earthquake that left 4 dead. Three days later, a 6.6 earthquake left 6 dead and caused a power outage (Datta & Kamal, 2012, p. 793).

MANY TOHOKU AFTERSHOCKS

MAPPED OUTImage courtesy of USGS(http://earthquake.usgs.gov/earthquakes/seqs/events/usc0001xgp/)

FORESHOCKS

There was one earthquake that occurred before the main earthquake. It was believed to be a foreshock of Tohoku. The earthquake occurred on March 9, 2011 (two days before the main earthquake), and had a magnitude of 7.3. It was a slow slip, but scientists believe that it is what led up to the 9.0 earthquake on March 11, 2011 (Datta & Kamal, 2012, p. 795).

AN EXAMPLE OF A FORESHOCK USING THE ANZA EARTHQUAKE’S

SEISMOGRAPH RESULTS

Image courtesy of NBC(http://www.nbcsandiego.com/video/#!/on-air/as-seen-on/Anza-Earthquake-May-be-a-Foreshock/197253711)

JAPAN RECOVERY

Images courtesy of CBS(http://www.cbsnews.com/pictures/japan-tsunami-recovery-then-and-now/4/)

WORKS CITED

Chai, Carmen (11 March 2011). "Japan's quake shifts earth's axis by 25 centimetres". Montreal Gazette (Postmedia News). Archived from the original on 13 March 2011. Retrieved 24 November 2013.

Chang, Kenneth (13 March 2011). "Quake Moves Japan Closer to U.S. and Alters Earth's Spin". The New York Times. Archived from the original on 16 March 2011. Retrieved 24 November 2013.

Datta, A., & Kamal. (2012). Triggering of aftershocks of the Japan 2011 earthquake by Earth tides. Current Science, 792-796.

Gross, Richard (19 March 2011). "Japan Earthquake May Have Shifted Earth’s Axis". NPR online.

Hashimoto, C., Noda, A., & Matsu'ura, M. (2012). The Mw 9.0 northeast Japan earthquake: total rupture of a basement asperity. Geophysical Journal International, 1-5.

Kawasumi, H., 1951, Measures of earthquakes danger and expectancy of maximum intensity throughout Japan as inferred from the seismic activity in historical times, Bull. Earthq. Res. Inst., Univ. Tokyo, 29, 469-482.

Rajendran, K., Andrade, V., Thulasiraman, N., & Rajendran, C. P. (2011). The 11 March 2011 Tohoku (Sendai), Japan earthquake. Current Science, 966-969.

Stimpson, I. (2011). Japan's Tohoku Earthquake and Tsunami. Geology Today, 96-98.

Wald, L. (2012, July 24). The Science of Earthquakes. Retrieved from USGS: http://earthquake.usgs.gov/learn/kids/eqscience.php

What is the "magnitude" of an earthquake? (2012). Retrieved from Geological Survey of Canada: http://www.okgeosurvey1.gov/magnitude_e.html

Witze, A. (2012). Making Waves. Science News, 22-25.