2001 Geiyo earthquake
Earthquake in Japan
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The 2001 Geiyo earthquake (2001年芸予地震 Nisen-ichi-nen Gēyo Jishin) occurred with a magnitude of MJMA 6.7 on March 24 at 15:27:53 JST, and an epicenter located near the Geiyo Islands of Hiroshima, Japan.[2]
| 芸予地震 | |
USGS ShakeMap | |
  Location within Hiroshima Prefecture  Location within Japan | |
| UTC time |
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| ISC event | |
| USGS-ANSS | |
| Local date |
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| Local time | |
| Magnitude | |
| Depth |
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| Epicenter | 34.083°N 132.526°E |
| Type | Normal |
| Areas affected | Chūgoku and Shikoku regions, Japan |
| Total damage | ¥77.6 billion (US$500 million) ($886.1 million in 2024, adjusted for inflation)[1] |
| Max. intensity | JMA 6− (MMI IX) |
| Peak acceleration | 0.85 g (832 gal) |
| Casualties | 2 fatalities, 288 injuries |
Tectonic setting
Near the Geiyo region, a Ms 7.8 earthquake occurred in June 1905,[3] which was an intraslab event within the subducting Philippine Sea plate.[4]
Earthquake
The United States Geological Survey (USGS) gave the earthquake a magnitude of Mw 6.8, while the Japan Meteorological Agency (JMA) reported the magnitude at MJMA 6.7, with its epicenter located near the island of Kurahashi-jima in Kure, Hiroshima Prefecture.[2][5] The released seismic moment of the earthquake was 1.3×1019 Nm. This earthquake is a normal faulting intraslab event within the subducting Philippine Sea plate.[6] The slip of the earthquake was estimated to be about 1.5–2.4 meters (4 ft 11 in – 7 ft 10 in). The locations of aftershocks were distributed roughly in N–S direction.[7] It has been suggested that this earthquake was related to the dehydration of the Philippine Sea plate slab.[8]
Intensity
| Intensity | Prefecture | Locations |
|---|---|---|
| 6− | Hiroshima | Higashihiroshima, Ōsakikamijima, Kumano |
| 5+ | Hiroshima | Kure, Etajima, Hiroshima, Hatsukaichi, Mihara, Onomichi, Kitahiroshima |
| Ehime | Kamijima, Imabari, Saijō, Kumakōgen, Matsuyama, Masaki, Seiyo, Uwajima, Tobe | |
| Yamaguchi | Suō-Ōshima, Yanai, Tabuse, Hirao, Waki, Iwakuni, Yamaguchi | |
| 5− | Hiroshima | Fukuyama, Sera, Miyoshi |
| Ehime | Ikata, Yawatahama, Ōzu, Uchiko, Iyo, Tōon, Niihama | |
| Yamaguchi | Kaminoseki, Hikari, Kudamatsu, Shūnan | |
| Shimane | Gōtsu, Hamada, Ōnan | |
| Kōchi | Kōchi | |
| Ōita | Saiki | |
The JMA reported it recorded a maximum seismic intensity of Shindo 6- on its seismic intensity scale; the maximum intensity was reported in Higashihiroshima, Ōsakikamijima and Kumano, Hiroshima Prefecture. Shindo 5+ was recorded in parts of Ehime and Yamaguchi Prefectures, while Shindo 5- was observed in multiple areas of Shimane, Kōchi and Ōita Prefectures; Shindo 1-4 was also reported in Kyushu, Kansai and Chūbu regions, with shaking recorded as far away as Shizuoka, Noto, Ishikawa, Iizuna and Kōzushima, Tokyo.[5] A maximum peak ground acceleration of 832 gal (0.85 g) was recorded at Saeki-ku, Hiroshima; strong ground motions from the earthquake were amplified and spread to areas far from the epicenter, due to the ground beneath the region comprising soft sediments.[9] On the Modified Mercalli intensity scale, the earthquake registered a maximum intensity of IX (Violent).[1] Tremors were also felt along the eastern and southern coasts of South Korea.[10]
Impact
Two people were killed; one in Kure, Hiroshima due to a wall collapse and the other in Matsuyama, Ehime after being hit by falling roof tiles.[11][10] Additionally, 288 others were injured, 43 of them seriously, including 183 in Hiroshima, 75 in Ehime, 12 in Yamaguchi, 4 in Kochi, 3 in Shimane and 1 in Okayama. The earthquake destroyed 76 homes, severely damaged 865 and partially damaged 53,243 others, with all structural collapses occurring in Hiroshima, Ehime and Yamaguchi; landslides destroyed 39 homes, mostly in Hiroshima. Additionally, 40,739 waterways, 1,209 cultural and educational facilities, 787 roads, 149 harbors, 97 hospitals, 9 bridges, 8 public buildings and 71 other structures were also affected.[12]
In Hiroshima, over 3,700 buildings were damaged,[2] train lines were suspended, Hiroshima Airport was temporarily closed for inspection, telecommunications were disrupted and soil liquefaction was reported.[10][13] Most of the damaged residential buildings in the city were built on steep slopes.[14] Liquefaction also occurred at Tōyo, Ehime.[15] Power outages occurred in the prefectures of Hiroshima, Ehime, Okayama, Yamaguchi, and Kōchi.[16]