Tokai earthquakes
Encyclopedia
The Tōkai earthquakes are major earthquakes
that have occurred regularly with an interval of 100 to 150 years in the Tōkai region
of Japan
. The Tokai segment has been struck by earthquakes in 1498, 1605, 1707 and 1854. Given the historic regularity of these earthquakes, Kiyoo Mogi
in 1969 pointed out that another great shallow earthquake was possible in the "near future" (i.e., in the next few decades).
Given the magnitude of the last two earthquakes, the next is expected to have at least moment magnitude (energy) 8, with large areas shaken at the highest level in the Japanese intensity scale
, 7. Emergency planners are anticipating and preparing for potential scenarios after such an earthquake, including the possibility of thousands of deaths and hundreds of thousands of injuries, millions of damaged buildings, and cities that include Nagoya and Shizuoka devastated. Concern has been expressed over the presence of the Hamaoka Nuclear Power Plant
, close to the expected epicentre of a Tokai earthquake. The Fukushima I Nuclear Power Plant
was severely damaged after a large earthquake followed by a tsunami in 2011
, causing a nuclear event of level 7
, the highest on the scale.
with predicting the next one. There is now a dense array of instruments placed to accumulate a continuous stream of data related to seismicity, strain, crustal expansion, tilt, tidal variations, ground water fluctuations and other variables. They are watching for an anomaly in this data which might precede the next major Tokai earthquake.
Following the prediction of an earthquake in the relatively near future, and in order to try to predict when it would occur, the Coordinating Committee for Earthquake Prediction
(CCEP) designated the Tokai region as an Area of Specific Observation in 1970, and upgraded it to an Area of Intensified Observation in 1974. Following the passing of the Large-Scale Earthquake Countermeasure Act
in 1978, the Earthquake Assessment Committee (EAC) was set up to warn the Prime Minister, via the Japan Meteorological Agency, if the next quake is imminent.
On all but one occasion, rupture of segment C (±D ±E) has been followed by rupture of segments A+B within a few years. This behavior has been reproduced by modeling the viscoelastic response of the megathrust fault plane with lateral variations in both convergence rate and frictional properties.
Earthquake
An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...
that have occurred regularly with an interval of 100 to 150 years in the Tōkai region
Tokai region
The is a sub-region of the Chūbu region in Japan that runs along the Pacific Ocean. The name means "East sea" and comes from the Tōkaidō, one of the Edo Five Routes...
of Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. The Tokai segment has been struck by earthquakes in 1498, 1605, 1707 and 1854. Given the historic regularity of these earthquakes, Kiyoo Mogi
Kiyoo Mogi
Dr is a prominent seismologist. He is regarded as Japan's foremost authority on earthquake prediction and is a former chair of the Japanese Coordinating Committee for Earthquake Prediction . Mogi is also a former Director of the University of Tokyo's Earthquake Research Institute, was a professor...
in 1969 pointed out that another great shallow earthquake was possible in the "near future" (i.e., in the next few decades).
Given the magnitude of the last two earthquakes, the next is expected to have at least moment magnitude (energy) 8, with large areas shaken at the highest level in the Japanese intensity scale
Japan Meteorological Agency seismic intensity scale
The Japan Meteorological Agency seismic intensity scale is a seismic scale used in Japan and Taiwan to measure the intensity of earthquakes. It is measured in units of...
, 7. Emergency planners are anticipating and preparing for potential scenarios after such an earthquake, including the possibility of thousands of deaths and hundreds of thousands of injuries, millions of damaged buildings, and cities that include Nagoya and Shizuoka devastated. Concern has been expressed over the presence of the Hamaoka Nuclear Power Plant
Hamaoka Nuclear Power Plant
The is a nuclear power plant located in Omaezaki city, Shizuoka Prefecture, on Japan's east coast, 200 km south-west of Tokyo. It is managed by the Chubu Electric Power Company. There are five units contained at a single site with a net area of 1.6 km2 . A sixth unit began construction...
, close to the expected epicentre of a Tokai earthquake. The Fukushima I Nuclear Power Plant
Fukushima I Nuclear Power Plant
The , also known as Fukushima Dai-ichi , is a disabled nuclear power plant located on a site in the towns of Okuma and Futaba in the Futaba District of Fukushima Prefecture, Japan. First commissioned in 1971, the plant consists of six boiling water reactors...
was severely damaged after a large earthquake followed by a tsunami in 2011
2011 Tōhoku earthquake and tsunami
The 2011 earthquake off the Pacific coast of Tohoku, also known as the 2011 Tohoku earthquake, or the Great East Japan Earthquake, was a magnitude 9.0 undersea megathrust earthquake off the coast of Japan that occurred at 14:46 JST on Friday, 11 March 2011, with the epicenter approximately east...
, causing a nuclear event of level 7
International Nuclear Event Scale
The International Nuclear and Radiological Event Scale was introduced in 1990 by the International Atomic Energy Agency in order to enable prompt communication of safety significance information in case of nuclear accidents....
, the highest on the scale.
Earthquake prediction
The Japanese government is taking the Tōkai earthquakes seriously and has charged the Japan Meteorological AgencyJapan Meteorological Agency
The or JMA, is the Japanese government's weather service. Charged with gathering and reporting weather data and forecasts in Japan, it is a semi-autonomous part of the Ministry of Land, Infrastructure and Transport...
with predicting the next one. There is now a dense array of instruments placed to accumulate a continuous stream of data related to seismicity, strain, crustal expansion, tilt, tidal variations, ground water fluctuations and other variables. They are watching for an anomaly in this data which might precede the next major Tokai earthquake.
Following the prediction of an earthquake in the relatively near future, and in order to try to predict when it would occur, the Coordinating Committee for Earthquake Prediction
Coordinating Committee for Earthquake Prediction
The Coordinating Committee for Earthquake Prediction in Japan was founded in April 1969, as part of the Geodesy Council's Second Earthquake Prediction Plan, in order to carry out a comprehensive evaluation of earthquake data in Japan. The committee consists of 30 members and meets four times each...
(CCEP) designated the Tokai region as an Area of Specific Observation in 1970, and upgraded it to an Area of Intensified Observation in 1974. Following the passing of the Large-Scale Earthquake Countermeasure Act
Large-Scale Earthquake Countermeasure Act
The Large-Scale Earthquake Countermeasures Act is a Japanese law that was passed in June 1978 and came into effect in December 1978.The Act put into place an integrated set of measures and created several bodies at national, prefecture and local levels...
in 1978, the Earthquake Assessment Committee (EAC) was set up to warn the Prime Minister, via the Japan Meteorological Agency, if the next quake is imminent.
Relation to other major earthquakes
The pattern of historical seismicity reveals that the megathrust surface is segmented, with five separate zones of rupturing identified, conventionally labeled A–E, from west to east. Earthquakes involving the A+B segments are generally referred to as Nankai (literally South Sea) earthquakes, C+D Tonankai (literally Southeast Sea) earthquakes and E Tokai (literally East Sea) earthquakes. These earthquakes repeat at intervals generally in the range of 90 – 200 years.On all but one occasion, rupture of segment C (±D ±E) has been followed by rupture of segments A+B within a few years. This behavior has been reproduced by modeling the viscoelastic response of the megathrust fault plane with lateral variations in both convergence rate and frictional properties.
Historical Tōkai earthquakes
| Date | Magnitude | Name | Death toll | Description |
|---|---|---|---|---|
| 8.3 | Hakuho earthquake | unknown | Landslides. Many houses, shrines and temples collapsed. | |
| 8.5 | Ninna earthquake | unknown | Many people were killed by collapsing houses. | |
| 8.4 | Kowa earthquake | unknown | The main building of the imperial palace was damaged, and the big bell of the Todai temple fell down. The tsunami in Suruga split houses, and 400 shrines and temples were damaged. | |
| 8.5 | Shohei earthquake | unknown | To be described. | |
| 8.4 | Meio earthquake 1498 Meiō Nankaidō earthquake The 1498 Meiō Nankaidō earthquake occurred off the coast of Nankai, Japan, at about 08:00 local time on 20 September, 1498. It had a magnitude estimated at 8.6 MS and triggered a large tsunami... |
40,000 | Kai had a major shake. The buildings around the great Buddha of Kamakura Kotoku-in is a Buddhist temple of the Jōdo-shū sect in the city of Kamakura in Kanagawa Prefecture, Japan.The temple is renowned for its , a monumental outdoor bronze statue of Amida Buddha which is one of the most famous icons of Japan.- The Great Buddha :... (altitude 7m) were swept away by tsunami. In Minato Hiroshi 1,000 households were destroyed with 5,000 people drowned. 10,000 people drowned in Ise-Shima, in Shida District, Shizuoka Prefecture, 26,000 people died. Nankai earthquakes also occurred around the same time according to the geological survey. |
|
| 7.9 | 1605 Keichō Nankaidō earthquake 1605 Keichō Nankaidō earthquake The 1605 Keichō Nankaidō earthquake occurred at about 20:00 local time on 3 February. It had an estimated magnitude of 7.9 on the surface wave magnitude scale and triggered a devastating tsunami that resulted in thousands of deaths in the Nankai and Tōkai regions of Japan. It is uncertain whether... |
2,300 | The tsunami attacked from the Pacific coast of Kyushu, Miyazaki, led to the deaths of 57 in Hachijo Island, destroyed 700 houses in a village west of Kii wide, 1,500 people died in Shishikui Awa, Tosa Nishinoura 350 deaths, and 400 in the vicinity of Cape Muroto. | |
| 8.4 | Hoei earthquake 1707 Hōei earthquake The 1707 Hōei earthquake, which occurred at 14:00 local time on October 28, 1707, was the largest in Japanese history until the 2011 Tōhoku earthquake surpassed it. It caused moderate to severe damage throughout southwestern Honshu, Shikoku and southeastern Kyūshū. The earthquake and the resulting... |
20,000 | Tokai, Tonankai and Nankai earthquakes occurred at the same time with magnitude 8.4–8.6. Mount Fuji Mount Fuji is the highest mountain in Japan at . An active stratovolcano that last erupted in 1707–08, Mount Fuji lies about south-west of Tokyo, and can be seen from there on a clear day. Mount Fuji's exceptionally symmetrical cone is a well-known symbol of Japan and it is frequently depicted in art and... erupted 49 days after this earthquake and the Hoei crater was created. About 20,000 people were killed and 60,000 houses collapsed, the Tosa area was affected by the tsunami. |
|
| 8.4 | Ansei-Tokai earthquake 1854 Ansei-Tōkai earthquake The 1854 Ansei-Tōkai earthquake was the first of the Ansei Great Earthquakes . It occurred at about 09:00 local time on 23 December, 1854. It had a magnitude of 8.4 and caused a damaging tsunami... |
3,000 | The epicenter Epicenter The epicenter or epicentre is the point on the Earth's surface that is directly above the hypocenter or focus, the point where an earthquake or underground explosion originates... ranged from Suruga Bay to the deep ocean, and struck primarily in the Tōkai region, but destroyed houses as far away as Edo Edo , also romanized as Yedo or Yeddo, is the former name of the Japanese capital Tokyo, and was the seat of power for the Tokugawa shogunate which ruled Japan from 1603 to 1868... . The accompanying tsunami Tsunami A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake... caused damage along the entire coast from the Bōsō Peninsula Boso Peninsula thumb|Locationthumb|Landsat image with high-resolution data from Space Shuttle is a peninsula in Chiba prefecture on Honshū, the largest island of Japan. It forms the eastern edge of Tokyo Bay, separating it from the Pacific Ocean.... in modern-day Chiba prefecture Chiba Prefecture is a prefecture of Japan located in the Kantō region and the Greater Tokyo Area. Its capital is Chiba City.- History :Chiba Prefecture was established on June 15, 1873 with the merger of Kisarazu Prefecture and Inba Prefecture... to Tosa province Tosa Province is the name of a former province of Japan in the area that is today Kōchi Prefecture on Shikoku. Tosa was bordered by Iyo and Awa Provinces. It was sometimes called .-History:The ancient capital was near modern Nankoku... (modern-day Kōchi prefecture Kochi Prefecture is a prefecture of Japan located on the south coast of Shikoku. The capital is the city of Kōchi.- History :Prior to the Meiji Restoration, Kōchi was known as Tosa Province and was controlled by the Chosokabe clan in the Sengoku period and the Yamauchi family during the Edo period.- Geography... ). |
See also
- Tonankai earthquakes
- 1944 Tōnankai earthquake1944 Tōnankai earthquakeThe 1944 Tōnankai earthquake occurred at 13:35 local time on 7 December. It had an estimated magnitude of 8.1 on the moment magnitude scale and a maximum felt intensity of greater than 5 shindo . It triggered a large tsunami that caused serious damage along the coast of Wakayama Prefecture and the...
- 1944 Tōnankai earthquake
- Nankai megathrust earthquakes
- Kanto earthquakeKanto earthquakecan refer to any of the historical earthquakes to occur in the Kantō region that originate from slippage in the Sagami Trough. Although the 1854 Ansei Great Earthquakes also struck in the region, this term is never used to refer to these quakes.It can refer to:...
- List of earthquakes in Japan
External links
- Tokai earthquake information from Japan Meteorological AgencyJapan Meteorological AgencyThe or JMA, is the Japanese government's weather service. Charged with gathering and reporting weather data and forecasts in Japan, it is a semi-autonomous part of the Ministry of Land, Infrastructure and Transport...
- Tokai earthquake preparedness in Shizuoka prefecture