2018 Hokkaido Eastern Iburi earthquake

2018 Hokkaido Eastern Iburi earthquake
2018 Hokkaido Eastern Iburi earthquake is located in Japan
2018 Hokkaido Eastern Iburi earthquake
Sapporo
Sapporo
UTC time2018-09-05 18:07:58
ISC event
USGS-ComCat
Local date6 September 2018 (2018-09-06)
Local time3:08 a.m. JST
Magnitude6.6 Mw
Depth35.0 km (22 mi)
Epicenter42°40′16″N 141°55′59″E / 42°40′16″N 141°55′59″E / 42.671; 141.933
TypeDip-slip (reverse)
Intraplate earthquake[1]
Max. intensityIX (Violent)
7 (X–XII (Extreme))
TsunamiNo
LandslidesYes
Aftershocks129
Largest: Mw 5.4 on 6 September (6:04 a.m. JST)[2]
Casualties41 dead, 691 injuries[3]

An earthquake measuring 6.6 MW on the moment magnitude scale struck Iburi Subprefecture in southern Hokkaido, Japan, on 6 September 2018 at 3:08 a.m. Japan Standard Time. The earthquake's epicenter was near Tomakomai and occurred at a depth of 35.0 kilometres (21.7 mi). The Japan Meteorological Agency (JMA) registered a magnitude of 6.7 Mj and a maximum intensity of 7 on the shindo scale.[4]Shaking from the earthquake was felt strongly in Hokkaido and Aomori Prefecture, and shaking was felt as far away as the Kantō region.[5][6] The earthquake disrupted electrical service throughout Hokkaido, leaving 5.3 million residents without power. Forty-one people were confirmed dead and six hundred and ninety-one were injured.[3] The event is officially known as Heisei san-jū-nen Hokkaidō Iburi tōbu jishin (平成30年北海道胆振東部地震, "Hokkaido Eastern Iburi Earthquake of Heisei 30").

Geology

The central area of Hokkaido where the earthquake was centered is prone to earthquakes despite not being located on any plate boundary. According to a survey conducted by the Ministry of Education, Culture, Sports, Science and Technology, there are several active seismic zones in the central part of Hokkaido, including the Furano and Ishikari fault zones. Studies have shown that earthquakes occurred in 1910, 1974, 1981, 1982, and 2000 in the region. Among them, the 7.1 Mj 1982 earthquake off the coast of Urakawa was the largest earthquake in the history of the region. The earthquake caused casualties and damage in Tomakomai and Sapporo.[7] There are many volcanoes located near the earthquake's epicenter. The volcanoes distributed pumicite throughout the area which was later covered with a layer of heavier soil. The volcanic material is theorized to have caused landslides after being inundated during heavy rains due to its slippery nature. The wet pumice and the soil on top of it slid away after the shear forces of the earthquake ruptured the strata, causing the landslides that led to most of the casualties of the earthquake.[8]