1586 Tenshō earthquake

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1586 Tenshō earthquake

Local date	January 18, 1586 (1586-01-18)
Magnitude	7.9-8.2 Ms
Epicenter	35°00′N 136°48′E / 35.0°N 136.8°E / 35.0; 136.8Coordinates: 35°00′N 136°48′E / 35.0°N 136.8°E / 35.0; 136.8
Tsunami	yes
Casualties	8,000 dead (est)

The 1586 Tenshō earthquake (天正地震, Tenshō Jishin) was a regional Japanese earthquake that occurred on January 18 in the year 1586. This earthquake had an estimated surface-wave magnitude (M_s ) of between 7.9 to 8.1, and an epicenter somewhere in the Chūbu region. It caused the deaths of at least 8,000 Japanese and damaged 10,000 houses throughout the prefectures of Toyama, Hyōgo, Kyōto, Osaka, Nara, Mie, Aichi, Gifu, Fukui, Ishikawa and Shizuoka.^[1]

Historical documentation of this earthquake is limited due to the fact that the earthquake occurred during the Sengoku Period in Japan.

Earthquake[]

The origin of the Tenshō earthquake is not known, but several geologists have presented different faults to be the possible source. There is still debate about which fault zone caused the earthquake and even how did the earthquake unfold, through a single fault system rupture or even a multiple fault system ruptures, given the massive death and destruction across wide areas of the Tōkai, Kinki, and Hokuriku regions.

The Atera Fault System (阿寺断層帯) that runs through the Chubu region is a northwest-striking left-lateral fault with a length of 60 km.^[2] The suggested epicenter is located near the northwest part of Gifu Prefecture, based on analyzing the damage distribution. In addition, soil surveys have found that the fault ruptured in 1586.^[3] The forested area in the region shows evidence of en-echelon fractures. A pond is also thought to have formed from the earthquake, it is most likely a sag pond that has now been converted into a paddy field. Further surveys revealed that another structure; the Miboro Fault, a northwest strand of the Atera Fault was also involved in the earthquake, bringing the total estimated rupture length to 85 km.^[2] Additional surveys and drilling found that the Yōrō-Kuwana-Yokkaichi Fault Zone (養老ー桑名ー四日市断層帯) to the west of the Nōbi Plain may have also been involved, and corresponds to reports of severe damage in the vicinity.^[4] It also has signs that the last earthquake on that fault zone could have happened between the 13th and 16th centuries, and it hence corresponds to the time of the earthquake (1586).

Damage[]

The earthquake had a maximum JMA intensity of Shindo 6 to 7 extending from the Noto Peninsula to Lake Biwa.^[5]

Large-scale landslides occurred in the northern part of the damage zone which was dominated by mountains. A fortress was completely wiped out by one of these landslides, while another collapsed during the tremors.^[5]

There are reports that a few small islands vanished in the Kiso River as a result of soil liquefaction and subsequent subsidence which caused water to submerge the islands while a tsunami was generated in Ise Bay, drowning thousands.^[5]

At the location of present-day Nagoya, extensive soil liquefaction took place. Sand volcanoes and dykes were recorded and discovered at locations in the plain.^[5]

Temples in Kyoto sustained minor damage.^[5]

See also[]

• List of earthquakes in Japan

References[]