2000 Izu Islands earthquakes

2000 Izu Islands earthquakes
USGS ShakeMap for the event on 30 July
2000 Izu Islands earthquakes is located in Japan
2000 Izu Islands earthquakes
UTC time2000-07-30 12:25:45
ISC event1738464
USGS-ANSSComCat
Local dateStarted: 26 June 2000 (2000-06-26)
Ended: 29 September 2000 (2000-09-29)
Local time21:25:45 JST (UTC+9)
Magnitude6.5 Mw(largest tremor) 
Epicenter33°54′04″N 139°22′34″E / 33.901°N 139.376°E / 33.901; 139.376
Areas affectedIzu Islands, Japan
Max. intensityJMA 6− (MMI VII)
Casualties1 dead, 15 injured

The 2000 Izu Islands earthquakes is an earthquake swarm that occurred around Miyake-jima, Kōzu-shima, and Nii-jima in the Izu Islands after 26 June 2000. The largest earthquake was Mw 6.5,[1] and six earthquakes with a maximum JMA seismic intensity of Shindo 6- and Modified Mercalli intensity of VI–VII, resulting in a large-scale earthquake swarm.[2]

Cause

An earthquake swarm is believed to be strongly related to volcanic activity on Miyake-jima. When seismic activity began around 18:30 JST (09:30 UTC) on 26 June, the Japan Meteorological Agency issued an volcanic information announcement at 19:33 JST (10:33 UTC) on the same day, calling for caution regarding volcanic eruptions on Miyake-jima. However, there was no immediate eruption on Miyake-jima, and the next day, discoloration of seawater believed to be caused by submarine volcanic eruptions was confirmed about 1 km off the west coast of Miyake-jima. It was believed that the seismic activity moved northwestward and the possibility of an eruption on Miyake-jima decreased, but on 8 July, an eruption occurred at the summit of Miyake-jima. The depression grew with frequent phreatic eruptions to a 550m–deep–caldera with adiameter of about 1,600 m.[3] There were small eruptions on 13 August, 14, and on 18 August, the largest eruption occurred, followed by the second largest eruption on 29 August, leading to the evacuation of all residents on the island.[4][5]

Seismic activity

From around 18:30 JST (09:30 UTC) on 26 June 2000, small-scale seismic activity began with the epicenter located in the southwest of Miyake-jima. On the 27th, the epicenter shifted to the west of Miyake-jima offshore. The seismic activity also spread northwestward and intensified. From late June to August, it became significant seismic activity in the waters off the west coast of Miyake-jima, as well as near Nii-jima and Kōzu-shima. There were 30 earthquakes with a maximum JMA seismic intensity of Shindo 5- or higher (Shindo 6- occurred 6 times, Shindo 5+ occurred 7 times, and Shindo 5- occurred 17 times). The total number of earthquakes reached 14,200. Seismic activity gradually subsided after September.[2]

List of earthquakes with a seismic intensity of Shindo 6− and higher
Time (JST) Epicenter Magnitude
(USGS) 		Intensity
(Shindo) 		Depth Notes
1 July 16:01:56 34°13′16″N 139°07′52″E / 34.221°N 139.131°E / 34.221; 139.131 Mwc 6.1 6- 10 km (6 mi) [6][7]
9 July 03:57:44 34°03′11″N 139°07′34″E / 34.053°N 139.126°E / 34.053; 139.126 Mwc 5.9 6- 10 km (6 mi) [8][9]
15 July 10:30:32 34°19′08″N 139°15′36″E / 34.319°N 139.260°E / 34.319; 139.260 Mwc 6.1 6- 10 km (6 mi) [10][11]
30 July 21:25:46 33°54′04″N 139°22′34″E / 33.901°N 139.376°E / 33.901; 139.376 Mwc 6.5 6- 10 km (6 mi) [12][1]
18 August 10:52:22 34°07′37″N 139°10′48″E / 34.127°N 139.180°E / 34.127; 139.180 Mwc 5.7 6- 10 km (6 mi) [13][14]
18 August 12:49:12 34°13′52″N 139°09′18″E / 34.231°N 139.155°E / 34.231; 139.155 mb 4.9 6- 10 km (6 mi) [15][16]

Impact

The earthquake swarm caused collapsed houses and landslides on Nii-jima, Kōzu-shima, Shikine-jima, and Miyake-jima. The July 1 earthquake killed one person in a landslide at Kōzu-shima Village. This was the first fatality caused by an earthquake in Japan since the Great Hanshin earthquake in 1995.[5] It also injured 15 people, destroyed 15 houses, severely damaged 20 others and damaged 174 more.[17]

See also

References

  1. ^ a b "M 6.5 – 94 km SSE of Shimoda, Japan". United States Geological Survey. Retrieved 2 May 2024.
  2. ^ a b Shinji Toda; Ross S. Stein; Takeshi Sagiya (October 2009). "Evidence from the AD 2000 Izu islands earthquake swarm that stressing rate governs seismicity". Geological Survey of Japan. 419 (6902): 58–61. doi:10.1038/nature00997. PMID 12214230.
  3. ^ Seiya Uyeda; Masashi Hayakawa; Toshiyasu Nagao; Molchanov O. (June 2002). "Electric and magnetic phenomena observed before the volcano-seismic activity in 2000 in the Izu Island Region, Japan". National Academy of Sciences. doi:10.1073/pnas.072208499. PMC 124234.
  4. ^ "2000（平成12）年6月〜噴火" (in Japanese). Japan Meteorological Agency. Retrieved 3 May 2024.
  5. ^ a b "三宅島噴火及び新島・神津島近海を震源とする地震による災害" (in Japanese). Fire and Disaster Management Agency. Archived from the original on 20 October 2011. Retrieved 3 May 2024.
  6. ^ "Earthquake information". Japan Meteorological Agency. Retrieved 4 May 2024.
  7. ^ "M 6.1 – 53 km SSE of Shimoda, Japan". United States Geological Survey. Retrieved 4 May 2024.
  8. ^ "Earthquake information". Japan Meteorological Agency. Retrieved 4 May 2024.
  9. ^ "M 5.9 – 71 km SSE of Shimoda, Japan". United States Geological Survey. Retrieved 4 May 2024.
  10. ^ "Earthquake information". Japan Meteorological Agency. Retrieved 4 May 2024.
  11. ^ "M 6.1 – near the south coast of Honshu, Japan". United States Geological Survey. Retrieved 4 May 2024.
  12. ^ "Earthquake information". Japan Meteorological Agency. Retrieved 4 May 2024.
  13. ^ "Earthquake information". Japan Meteorological Agency. Retrieved 4 May 2024.
  14. ^ "M 5.7 – 64 km SSE of Shimoda, Japan". United States Geological Survey. Retrieved 4 May 2024.
  15. ^ "Earthquake information". Japan Meteorological Agency. Retrieved 4 May 2024.
  16. ^ "M 4.9 – 53 km SSE of Shimoda, Japan". United States Geological Survey. Retrieved 4 May 2024.
  17. ^ "日本付近で発生した主な被害地震（平成8年以降）" (in Japanese). Japan Meteorological Agency. Retrieved 2 May 2024.