1855 Ansei Edo earthquake
Encyclopedia
The , also known as the Great Ansei Earthquake, was one of the major disasters of the late-Edo period
Edo period
The , or , is a division of Japanese history which was ruled by the shoguns of the Tokugawa family, running from 1603 to 1868. The political entity of this period was the Tokugawa shogunate....

. The earthquake occurred at 22:00 local time on 11 November. It had an 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...

 close to 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...

 (now Tokyo
Tokyo
, ; officially , is one of the 47 prefectures of Japan. Tokyo is the capital of Japan, the center of the Greater Tokyo Area, and the largest metropolitan area of Japan. It is the seat of the Japanese government and the Imperial Palace, and the home of the Japanese Imperial Family...

), causing considerable damage in the Kantō region
Kanto region
The is a geographical area of Honshu, the largest island of Japan. The region includes the Greater Tokyo Area and encompasses seven prefectures: Gunma, Tochigi, Ibaraki, Saitama, Tokyo, Chiba, and Kanagawa. Within its boundaries, slightly more than 40 percent of the land area is the Kantō Plain....

 from the shaking and subsequent fires, with a death toll of about 7,000 people. The earthquake had a magnitude of 7.0 on the surface wave magnitude scale
Surface wave magnitude
The surface wave magnitude scale is one of the magnitude scales used in seismology to describe the size of an earthquake. It is based on measurements in Rayleigh surface waves that travel primarily along the uppermost layers of the earth...

 and reached a maximum intensity of XI (Extreme) on the Mercalli intensity scale
Mercalli intensity scale
The Mercalli intensity scale is a seismic scale used for measuring the intensity of an earthquake. It measures the effects of an earthquake, and is distinct from the moment magnitude M_w usually reported for an earthquake , which is a measure of the energy released...

. The earthquake triggered a minor 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...

.

Tectonic setting

The Kanto area lies above a complex part of the convergent boundaries
Convergent boundary
In plate tectonics, a convergent boundary, also known as a destructive plate boundary , is an actively deforming region where two tectonic plates or fragments of lithosphere move toward one another and collide...

 between the subducting
Subduction
In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...

 Pacific
Pacific Plate
The Pacific Plate is an oceanic tectonic plate that lies beneath the Pacific Ocean. At 103 million square kilometres, it is the largest tectonic plate....

 and Philippine Sea Plates and the overriding Eurasian Plate
Eurasian Plate
The Eurasian Plate is a tectonic plate which includes most of the continent of Eurasia , with the notable exceptions of the Indian subcontinent, the Arabian subcontinent, and the area east of the Chersky Range in East Siberia...

. Earthquakes with epicenters in the Kanto region may occur within the Eurasian Plate, at the Eurasaian Plate/Philippine Sea Plate interface, within the Philippine Sea Plate, at the Philippine Sea Plate/Pacific Plate interface or within the Pacific Plate. In addition to this set of major plates it has been suggested that there is also a separate 25 km thick, 100 km wide body, a fragment of Pacific Plate lithosphere
Lithosphere
The lithosphere is the rigid outermost shell of a rocky planet. On Earth, it comprises the crust and the portion of the upper mantle that behaves elastically on time scales of thousands of years or greater.- Earth's lithosphere :...

. The 1855 earthquake is consistent with a rupture along the interface between the Eurasian and Philippine Sea Plates, adjacent to, and down dip from, the rupture that caused the 1923 Great Kantō earthquake
1923 Great Kanto earthquake
The struck the Kantō plain on the Japanese main island of Honshū at 11:58:44 am JST on September 1, 1923. Varied accounts hold that the duration of the earthquake was between 4 and 10 minutes...

.

Damage

A total of about 50,000 houses and over 50 temples were either destroyed by the earthquake shaking or subsequent fires. The area burned down in Edo was about 2.3 km2.

Aftermath

Two days after the earthquake, prints began to appear, with more than 400 different types being available in the following weeks. Most of the prints depicted giant catfish
Catfish
Catfishes are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores...

, a type of image known as Namazu-e. The significance being that earthquakes at the time were popularly attributed to the thrashing about of a mythological catfish under the earth, normally kept under control by the deity Kashima using a large rock. The number of prints produced during the 1855 earthquake was unprecedented and has been related to the political and social effects of the disaster. The prints show the people's anger with Kashima who became replaced by the solar deity Amaterasu
Amaterasu
, or is apart of the Japanese myth cycle and also a major deity of the Shinto religion. She is the goddess of the sun, but also of the universe. the name Amaterasu derived from Amateru meaning "shining in heaven." The meaning of her whole name, Amaterasu-ōmikami, is "the great August kami who...

. Some of the prints also depict the redistribution of wealth. The earthquake has been described as an act of yonaoshi or 'world rectification', in the light of the two great
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...

 earthquakes
1854 Ansei-Nankai earthquake
The 1854 Ansei-Nankai earthquake occurred at about 16:00 local time on 24 December, 1854. It had a magnitude of 8.4 and caused a damaging tsunami...

 of 1854 and the arrival of Perry's Black Ships
Black Ships
The Black Ships was the name given to Western vessels arriving in Japan in the 16th and 19th centuries.In 1543 Portuguese initiated the first contacts, establishing a trade route linking Goa to Nagasaki...

 in 1853.

Era of Disaster

Three large earthquakes, the 1854 Ansei-Tōkai 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...

, 1854 Ansei-Nankai earthquake
1854 Ansei-Nankai earthquake
The 1854 Ansei-Nankai earthquake occurred at about 16:00 local time on 24 December, 1854. It had a magnitude of 8.4 and caused a damaging tsunami...

, and the 1855 Ansei Edo earthquake are collectively called the Ansei Great Earthquakes (安政の大地震, Ansei no Dai Jishin). Combining the effects of these disasters with a major cholera outbreak killing over 100,000 people, a fire at Edo Castle
Edo Castle
, also known as , is a flatland castle that was built in 1457 by Ōta Dōkan. It is located in Chiyoda in Tokyo, then known as Edo, Toshima District, Musashi Province. Tokugawa Ieyasu established the Tokugawa shogunate here. It was the residence of the shogun and location of the shogunate, and also...

, and the 1858 Hietsu earthquake
1858 Hietsu earthquake
The took place on April 9, 1858 . It occurred on the Atotsugawa Fault, which connects the Amō Pass in Gifu Prefecture and Mount Tate in Toyama Prefecture on the island of Honshū in Japan. Its name includes one kanji from and one from...

, the Ansei
Ansei
was a after Kaei and before Man'en. This period spanned the years from November 1854 through March 1860. The reigning emperor was .- Change of era :...

era was one of quite catastrophic upheaval. Due to the cumulative effects of these disasters, the reign name was changed in 1860 to usher in a 'clean slate' and better "fortune".
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