1703 Genroku earthquake
Encyclopedia
The occurred at 02:00 local time on December 31 (17:00 December 30 UTC
Coordinated Universal Time
Coordinated Universal Time is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose...

). 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...

 was near 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 forerunner of present-day 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...

, in the southern part of 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....

, 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...

. It shook Edo and an estimated 2,300 people were killed by the shaking and subsequent fires. The earthquake triggered a major 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...

 which caused many casualties, giving a total death toll of at least 5,233, possibly up to 10,000. Genroku
Genroku
was a after Jōkyō and before Hōei. This period spanned the years from September 1688 through March 1704. The reigning emperor was .The years of Genroku are generally considered to be the Golden Age of the Edo Period. The previous hundred years of peace and seclusion in Japan had created relative...

 is a Japanese era
Japanese era name
The Japanese era calendar scheme is a common calendar scheme used in Japan, which identifies a year by the combination of the and the year number within the era...

 spanning from 1688 through 1704.

Tectonic setting

The Kantō Region lies at the complex triple junction
Triple junction
A triple junction is the point where the boundaries of three tectonic plates meet. At the triple junction a boundary will be one of 3 types - a ridge, trench or transform fault - and triple junctions can be described according to the types of plate margin that meet at them...

, where 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...

 meet. Earthquakes with epicenters in the Kanto region may occur within the Eurasian Plate, at the Eurasian 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 1703 earthquake is thought to have involved rupture of the interface between the Eurasian Plate and the Philippine Sea Plate.

Earthquake

The earthquake was associated with areas of both uplift and subsidence. On both the Boso Peninsula and Miura Peninsula
Miura Peninsula
is a peninsula located in Kanagawa, Japan. It lies south of Yokohama and Tokyo and divides Tokyo Bay, to the east, from Sagami Bay, to the west. Cities and towns on the Miura Peninsula include Yokosuka, Miura, Hayama, Zushi, and Kamakura....

 a clear paleo shoreline has been identified, indicating up to 5 m of uplift near Mera
Mera
- Places :*Mera, Dhanbad, a town in India*Mera, Pastaza, a town in Ecuador*Shell Mera, Pastaza, a town in Ecuador*Méra, a village in Borsod-Abaúj-Zemplén County, Hungary*Mera, Vrancea, a commune in Romania*Mera , a village in Baciu Commune, Cluj County, Romania...

 and up to 1.2 m of uplift on Miura, increasing to the south. This distribution of uplift, coupled with modelling of the tsunami, indicate that at least two and probably three fault segments ruptured during the earthquake.

Tsunami

The tsunami had run-up heights of 5m or more over a wide area, with a maximum of 10.5 m at Wada
Wada, Chiba
is a former town located in Awa District, Chiba, Japan. As of March 20, 2006, the town had an estimated population of 5,717 and a density of 176 persons per km². The total area was 32.45 km².-Geography:...

 and 10 m at both Izu Ōshima
Izu Oshima
is a volcanic island in the Izu Islands and administered by the Tokyo Metropolitan government, Japan, lies about 100 km south of Tokyo, 22 km east of the Izu Peninsula and 36 km southwest of Bōsō Peninsula. serves as the local government of the island...

 and Ainohama.

Damage

The area of greatest damage due to the earthquake shaking was in Kanagawa Prefecture
Kanagawa Prefecture
is a prefecture located in the southern Kantō region of Japan. The capital is Yokohama. Kanagawa is part of the Greater Tokyo Area.-History:The prefecture has some archaeological sites going back to the Jōmon period...

, although Shizuoka Prefecture
Shizuoka Prefecture
is a prefecture of Japan located in the Chūbu region on Honshu island. The capital is the city of Shizuoka.- History :Shizuoka prefecture was formed from the former Tōtōmi, Suruga and Izu provinces.The area was the home of the first Tokugawa Shogun...

 was also affected. The earthquake caused many large fires, particularly at Odawara
Odawara, Kanagawa
is a city located in western Kanagawa Prefecture, Japan. As of 2010, the city had an estimated population of 198,466 with a population density of 1,740 persons per km² . The total area was .-Geography:...

, increasing both the degree of damage and the number of deaths. A total of 8,007 houses were destroyed by the shaking and a further 563 houses by the fires, causing 2,291 deaths. About 400 km of coastline was severely affected by the tsunami, with deaths being caused from Shimoda
Shimoda
Shimoda can mean:* Places in Japan:** Shimoda, Shizuoka, a city in Shizuoka Prefecture** Shimoda, Aomori, a town in Aomori Prefecture* Treaty of Shimoda , between Japan and Russia* Shimoda Toyomatsu, an early Japanese Scouting notable...

 on the east coast of the Izu Peninsula
Izu Peninsula
The is a large mountainous peninsula with deeply indented coasts to the west of Tokyo on the Pacific coast of the island of Honshū, Japan. Formerly the eponymous Izu Province, Izu peninsula is now a part of Shizuoka Prefecture...

 in the west to Isumi
Isumi, Chiba
is a city in Chiba Prefecture, Japan. As of March 1, 2010, the city has a population of 41,014 in an area of 157.50 km².Tōkyō Station is reached from Isumi by express train in 1 hour and 10 minutes via Ōhara Station on the JR East Sotobō Line.-Geography:...

 on the east side of 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....

 to the east. There was also a single death on the island of Hachijōjima
Hachijojima
is a volcanic Japanese island in the Philippine Sea, administered by Tōkyō and located approximately south of the Special Wards of Tōkyō. It is the southernmost and most isolated of the Izu Seven Islands group of the seven northern islands of the Izu archipelago...

about 180 km south of the earthquake's epicentre, where the tsunami was 3 m high. The total number of casualties from earthquake, fires and tsunami has been reported as 5,233. Other estimates are higher, with 10,000 in total, and one source that gives 200,000.

External links

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