The 1946 Nankai earthquake (昭和南海地震 Shōwa Nankai jishin) was a great

earthquake An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they ...

Nankaidō is a Japanese geographical term. It means both an ancient division of the country and the main road running through it. The road connected provincial capitals in this region. It was part of the Gokishichidō system. The Nankaidō encompassed the ...

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

. It occurred on December 21, 1946, at 04:19 JST (December 20, 19:19 UTC). The earthquake measured between 8.1 and 8.4 on the

moment magnitude scale The moment magnitude scale (MMS; denoted explicitly with or Mwg, and generally implied with use of a single M for magnitude) is a measure of an earthquake's magnitude ("size" or strength) based on its seismic moment. was defined in a 1979 paper ...

, and was felt from Northern

Honshū , historically known as , is the largest of the four main islands of Japan. It lies between the Pacific Ocean (east) and the Sea of Japan (west). It is the seventh-largest island in the world, and the second-most populous after the Indonesian ...

Kyūshū is the third-largest island of Japan's four main islands and the most southerly of the four largest islands (i.e. excluding Okinawa and the other Ryukyu (''Nansei'') Islands). In the past, it has been known as , and . The historical regio ...

. It occurred almost two years after the

1944 Tōnankai earthquake The 1944 Tōnankai earthquake occurred at 13:35 local time (04:35 UTC) on 7 December. It had an estimated magnitude of 8.1 on the moment magnitude scale (making it the strongest known earthquake of 1944) and a maximum felt intensity of greater th ...

, which ruptured the adjacent part of the Nankai megathrust.

Geology

The

Nankai Trough The is a submarine trough located south of the Nankaidō region of Japan's island of Honshu, extending approximately offshore. The underlying fault, the ''Nankai megathrust,'' is the source of the devastating Nankai megathrust earthquakes, ...

is a

convergent boundary A convergent boundary (also known as a destructive boundary) is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a ...

where the

Philippine Sea plate The Philippine Sea plate or the Philippine plate is a tectonic plate comprising oceanic lithosphere that lies beneath the Philippine Sea, to the east of the Philippines. Most segments of the Philippines, including northern Luzon, are part of ...

is being

subducted Subduction is a geological process in which the oceanic lithosphere and some continental lithosphere is recycled into the Earth's mantle at the convergent boundaries between tectonic plates. Where one tectonic plate converges with a second plat ...

beneath the Eurasian plate. Large earthquakes have been recorded along this zone since the 7th century, with a recurrence time of 100 to 200 years.

Earthquake

The 1946 Nankaido earthquake was unusual in its seismological perspective, with a rupture zone estimated from long-period geodetic data that was more than twice as large as that derived from shorter period seismic data. In the center of this earthquake rupture zone, scientists used densely deployed ocean bottom

seismograph A seismometer is an instrument that responds to ground displacement and shaking such as caused by quakes, volcanic eruptions, and explosions. They are usually combined with a timing device and a recording device to form a seismograph. The out ...

s to detect a subducted

seamount A seamount is a large submarine landform that rises from the ocean floor without reaching the water surface (sea level), and thus is not an island, islet, or cliff-rock. Seamounts are typically formed from extinct volcanoes that rise abruptly a ...

thick by wide at a depth of . Scientists propose that this seamount might work as a barrier inhibiting brittle seismogenic rupture.

Casualties and damage

The earthquake caused extensive damage, destroying 36,000 homes in southern Honshū alone. The earthquake also caused a huge tsunami that took out another 2,100 homes with its waves.

References

External links

* {{DEFAULTSORT:1946 Nankaido Earthquake Nankaido Nankaido Earthquake, 1946 1940s tsunamis December 1946 in Asia Megathrust earthquakes in Japan Occupied Japan Tsunamis in Japan Earthquakes of the Showa era 1946 disasters in Japan

Geology

Earthquake

Casualties and damage

See also

References

External links