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2024 Hyūga-nada earthquake

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2024 Hyūga-nada earthquake
Map of JMA seismic intensities
USGS ShakeMap
2024 Hyūga-nada earthquake is located in Kyushu
2024 Hyūga-nada earthquake
UTC time2024-08-08 07:42:55
USGS-ANSSComCat
Local date8 August 2024 (2024-08-08)
Local time16:42:55 JST
Duration~20 seconds[1]
Magnitude7.1 MJMA
7.1 Mw
Depth25 km (16 mi) (USGS)
31 km (19 mi) (JMA)
Epicenter31°43′08″N 131°31′37″E / 31.719°N 131.527°E / 31.719; 131.527
TypeReverse
Areas affectedKyushu, Japan
Max. intensityJMA 6− (MMI VIII)
Tsunami50 cm (1.6 ft)
LandslidesYes
Aftershocks5.5 Mw
Casualties16 injured

On 8 August 2024, at 16:42:55 JST (07:42 UTC), a Mw 7.1 earthquake struck in the Hyūga Sea off the coast of Miyazaki Prefecture, Kyushu, Japan, 20 km (12 mi) northeast of Nichinan.[2]

Tectonic setting

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The Hyūga Sea is located at the southwestern end of the Nankai Trough, an active subduction zone. The Nankai Trough represents the plate boundary where the Philippine Sea plate subducts beneath the Eurasian plate. The area is associated with large earthquakes in 1662 (Mw  7.9), 1941 (Mw  8.0), 1961 (Mw  7.5),[3] 1968 (Mw  7.5) and two in 1996 (Mw  6.6[4] and 6.7[5]). The Hyūga Sea is interpreted as a transition zone between the highly coupled Nankai Trough in the northeast and weakly coupled Ryukyu Trench further southwest.[6] The 1968 and 1996 earthquakes were subduction zone events occurring on the plate boundary. The 2016 Kumamoto earthquakes were about 140 km (87 mi) northwest of the 2024 Hyūga-nada earthquake and were caused by a similar subduction zone.[2] About 2 km (1.2 mi) beneath the seafloor, low-frequency earthquakes, occur near the shallow subduction interface. Beneath the east coast of Kyushu, on the deeper part of the subduction zone, slow slip events were detected between 1996 and 2017.[7]

Earthquake

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The United States Geological Survey reported a magnitude (Mww ) of 7.1, at a depth of 25 km (16 mi) and a maximum Modified Mercalli intensity of VIII (Severe).[2] At least 24 aftershocks were recorded following the event,[8] with the strongest measuring Mw 5.5.[9]

The USGS initially reported two events, measuring magnitudes 7.1 and 6.9 respectively. This was later fixed.[10]

Locations with a seismic intensity of Shindo 5− and higher[11]
Intensity Prefecture Locations
6− Miyazaki Nichinan
5+ Miyazaki Miyazaki, Kushima, Miyakonojō
Kagoshima Ōsaki
5− Miyazaki Mimata, Kunitomi, Shintomi, Takanabe, Takaharu, Kobayashi
Kagoshima Soo, Kanoya, Kimotsuki, Higashikushira, Tarumizu, Kirishima, Kagoshima, Aira

On August 9, 2024, at 7:57pm JST, a 5.3MJMA earthquake struck western Kanagawa Prefecture,[12] causing tremors recorded as a 5- on the JMA seismic intensity scale and injuring 3.[13] Many in the public believed this earthquake could be related, but Professor Sakai Shinichi of the University of Tokyo's Earthquake Research Institute stated that the Kanagawa earthquake was not related to the Hyūga-nada earthquake or a possible Nankai megathrust earthquake.[14]

Tsunami

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A tsunami advisory was issued after the earthquake. It covered Kōchi, Ehime, Oita, Miyazaki and Kagoshima Prefectures[15] and predicted waves of up to 1 m (3.3 ft).[16] Subsequently, tsunami waves of 50 cm (1.6 ft) were observed in Miyazaki, 30 cm (0.98 ft) in Kōchi, and 20 cm (0.66 ft) in Kagoshima.[15] The advisories were lifted at 22:00 JST.[17]

Impact

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Ground uplift in Kagoshima Prefecture after the earthquake
Damage in a house caused by the earthquake.

The earthquake injured at least 16 people, three of them in a serious condition, collapsed or severely damaged three houses and damaged 77 others across Kyushu.[18] Ten people were injured in Miyazaki Prefecture.[18] In Nichinan, the Obi Castle Town sustained damage. A section of National Route 220 was closed due to rockfalls. A house partially collapsed in Miyazaki, and ten buildings as well as the Miyazaki Airport received minor damage. Two flights each of All Nippon Airways and Solaseed Air were canceled, and some flights of Japan Airlines from the airport were delayed. Water pipe leaks occurred in Kushima. In Kagoshima Prefecture, four people were injured,[18] several walls and a two-story house collapsed, and roads were raised in Ōsaki. A landslide was reported in Shibushi. Two people were injured in Kumamoto Prefecture.[19][20][21][22]

Shinkansen services along the Kyushu and Nishi Kyushu lines were suspended, along with a ferry service from Kobe to Miyazaki. No abnormalities were detected at the Ikata and Sendai nuclear power plants located near the epicenter.[15]

Aftermath

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Information on delays due to reduced speed from earthquake warning for the Tōkaidō Shinkansen

Following the earthquake, the Japan Meteorological Agency (JMA) issued a 'Nankai Trough Earthquake Extra Information' advisory[23] that the probability of a megathrust earthquake along the Nankai Trough increased from a 0.1% per week to 1% chance[24] in what was the first advisory of its kind but clarified that it was not imminent.[10][25] While the JMA stated that no abnormal changes were observed by strain meters, they still maintained the advisory through at least August 14.[26] The JMA called for those living in areas expected to be impacted by a Nankai megathrust earthquake to follow disaster prevention measures provided by the government,[27] and advised households with children, elderly, or physically disabled individuals to consider voluntarily evacuating.[28] The Japanese government designated 707 municipalities in 29 prefectures, including Yokohama, Shizuoka, Hamamatsu, Nagoya, Kyoto, Osaka, Kobe, Okayama, Hiroshima, all of Shikoku, Miyazaki, and parts of Okinawa, as areas at risk of being affected by a strong tremor with an intensity of lower 6 or higher and a tsunami with a height of more than three meters.[29] The warning was eventually lifted on 15 August after the JMA said it had not detected major seismic activity.[30]

In response, the Central Japan Railway Company ordered trains at the Tokaido Shinkansen line to run at a slower pace for a week,[15] while Prime Minister Fumio Kishida cancelled a scheduled trip to Central Asia on 9 August[31] as part of government preparations for its possible occurrence.[32] Supermarkets issued a limit of 12 two-liter plastic bottles of water to be sold per family to discourage panic buying, while demand for drinking water, emergency toilets and preserved foods significantly increased in online shopping websites.[33]

Several hotel booking cancellations were reported across Japan due to the advisory, with at least 150 cancellations recorded in Miyazaki,[34] 200 at the Dōgo Onsen in Matsuyama, and over 9,400 participants cancelling their participation in the Yosakoi Matsuri in Kōchi. Many of these cancellations coincided with the Obon holiday week.[35]

See also

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References

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  1. ^ "M 7.1 – 2024 Hyuganada Sea, Japan Earthquake Finite Fault". United States Geological Survey. Retrieved 10 August 2024.
  2. ^ a b c ANSS. "M 7.1 – 20 km NE of Nichinan, Japan 2024". Comprehensive Catalog. U.S. Geological Survey.
  3. ^ "M 7.5 – 18 km NNE of Nichinan, Japan". United States Geological Survey. Retrieved 9 August 2024.
  4. ^ "M 6.6 – 20 km SSE of Nishinoomote, Japan". United States Geological Survey. Retrieved 10 August 2024.
  5. ^ "M 6.7 – 17 km SW of Miyazaki, Japan". United States Geological Survey. Retrieved 10 August 2024.
  6. ^ Asano, Youichi; Obara, Kazushige; Matsuzawa, Takanori; Hirose, Hitoshi; Ito, Yoshihiro (2015). "Possible shallow slow slip events in Hyuga-nada, Nankai subduction zone, inferred from the migration of very low frequency earthquakes". Geophysical Research Letters. 42 (12): 331–338. Bibcode:2015GeoRL..42..331A. doi:10.1002/2014GL062165.
  7. ^ Ioki, Kei; Yamashita, Yusuke; Kase, Yoshihiro (2023). "Effects of the Tsunami Generated by the 1662 Hyuga-Nada Earthquake off Miyazaki Prefecture, Japan". Pure and Applied Geophysics. 180 (6): 1897–1907. Bibcode:2023PApGe.180.1897I. doi:10.1007/s00024-022-03198-3. hdl:2433/284057.
  8. ^ "日向灘の地震の最大震度別地震回数表" (PDF) (in Japanese). Japan Meteorological Agency. Retrieved 14 August 2024.
  9. ^ "M 5.5 – 40 km E of Nichinan, Japan". United States Geological Survey. 16 September 2024. Retrieved 16 September 2024.
  10. ^ a b Osaki, Tomohiro (8 August 2024). "7.1-magnitude Earthquake Hits Off Japan". Barron's. Retrieved 8 August 2024.
  11. ^ "Earthquake information". Japan Meteorological Agency. 8 August 2024. Retrieved 8 August 2024.
  12. ^ "Earthquake information : Detail information". Japan Meteorological Agency. Retrieved 10 August 2024.
  13. ^ "神奈川県震度5弱 1週間程度は同程度の揺れの地震に注意 | NHK". NHKニュース. 10 August 2024.
  14. ^ "M5.3 quake hits eastern Japan | NHK WORLD-JAPAN News". NHK WORLD. NHK. 9 August 2024. Retrieved 10 August 2024.
  15. ^ a b c d "M7.1 quake hits southwestern Japan, megaquake fear grows". Kyodo News. 8 August 2024. Retrieved 8 August 2024.
  16. ^ "Strong earthquake with 7.1 magnitude hits off southern Japan, prompts tsunami advisory". CBS News. 8 August 2024. Retrieved 8 August 2024.
  17. ^ "Megaquake advisory issued, tsunami advisories lifted". NHK. 8 August 2024. Retrieved 8 August 2024.
  18. ^ a b c 宮崎県日向灘を震源とする地震による被害及び消防機関等の対応状況（第１１報） [Damage caused by the earthquake centered in Hyuga-Nada, Miyazaki Prefecture and the response of firefighting agencies (11th report)] (PDF). fdma.go.jp (in Japanese). 15 August 2024. Archived from the original (PDF) on 15 August 2024. Retrieved 15 August 2024.
  19. ^ 【被害】宮崎 日南市で2人けが 各地で住宅被害も [Damage: Two people were injured in Nichinan City, Miyazaki, Japan, and damage to houses in various areas.] (in Japanese). NHK. 8 August 2024. Retrieved 8 August 2024.
  20. ^ 最大震度6弱を観測 宮崎県内の地震被害まとめ（午後６時半時点） [Summary of earthquake damage in Miyazaki Prefecture (as of 6:30 p.m.), with a maximum intensity of 6] (in Japanese). TBS. 8 August 2024. Retrieved 8 August 2024.
  21. ^ Yamaguchi, Mari (8 August 2024). "A powerful quake hits off Japan's coast, causing minor injuries but prompting new concerns". Associated Press. Retrieved 9 August 2024.
  22. ^ "Japan issues first 'megaquake' warning after 7.1-magnitude temblor". NBC News. 9 August 2024. Retrieved 9 August 2024.
  23. ^ 南海トラフ地震臨時情報(巨大地震注意) [Nankai Trough Earthquake Emergency Information (Caution for a Major Earthquake)]. Japan Meteorological Agency. Retrieved 14 August 2024.
  24. ^ "【詳細】南海トラフ地震臨時情報「巨大地震注意」対象地域は". NHKニュース (in Japanese). 9 August 2024.
  25. ^ "Japan sees higher-than-usual risk of megaquake off Pacific Coast". Kyodo News. 8 August 2024. Retrieved 8 August 2024.
  26. ^ 南海トラフ地震関連解説情報(第６号) [Nankai Trough Earthquake Related Information (No. 6)]. Japan Meteorological Agency. Retrieved 14 August 2024.
  27. ^ "Megaquake advisory issued, tsunami advisories lifted". NHK. 8 August 2024. Retrieved 9 August 2024.
  28. ^ "Japan Meteorological Agency maintains mega-quake advisory for Nankai Trough". NHK WORLD. NHK. 9 August 2024. Retrieved 10 August 2024.
  29. ^ "南海トラフ巨大地震 揺れや津波に特に対策が必要な自治体は？". NHKニュース (in Japanese). 9 August 2024. Retrieved 12 August 2024.
  30. ^ "Japan lifts 'megaquake' warning after one week". BBC. 15 August 2024. Retrieved 15 August 2024.
  31. ^ "Japan PM scraps overseas trip after 'megaquake' advisory". France 24. Agence France-Presse. 9 August 2024. Retrieved 9 August 2024.
  32. ^ "Japan PM scraps Central Asia trip after 'megaquake' warning". Al Jazeera. 9 August 2024. Retrieved 9 August 2024.
  33. ^ "Japan urges public not to hoard disaster kits amid megaquake fear". Kyodo News. 9 August 2024. Retrieved 9 August 2024.
  34. ^ "Japan braces for potential massive quake after M7.1 temblor". Kyodo News. 9 August 2024. Retrieved 9 August 2024.
  35. ^ "Mega-quake advisory hurts summer tourism trade". NHK WORLD. 14 August 2024. Retrieved 14 August 2024.
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