2008 Iwate-Miyagi Nairiku earthquake

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Iwate-Miyagi Nairiku Earthquake in 2008
Matsurube Ohashi(bridge).JPG
USGS ShakeMap 2008tfdp.jpg
Date June 14, 2008 (2008-06-14) (JST)
Magnitude Mj 7.2 (JMA scale), Mw 6.9 (by USGS)
Depth 8 kilometres (5 mi) (JMA), 10 kilometres (6 mi) (USGS)
Epicenter 39°01.7′N 140°52.8′E / 39.0283°N 140.8800°E / 39.0283; 140.8800Coordinates: 39°01.7′N 140°52.8′E / 39.0283°N 140.8800°E / 39.0283; 140.8800
(Iwate Prefecture)
Areas affected Japan / Tōhoku region
Peak acceleration 4.36 g (vector sum)
Tsunami none
Aftershocks 483 felt aftershocks by July 1 (JMA)[1]
Largest: Mj 5.7 on June 14 ( 9:20 JST)
Casualties at least 12 dead, 436 injured (As of 2008-07-01 17:00 JST)

The 2008 Iwate earthquake on June 14, 2008 mainly struck mid Tōhoku region, northeastern Honshū, Japan.[2] Japan Meteorological Agency (JMA) officially named this earthquake the Iwate-Miyagi Nairiku Earthquake in 2008 (平成20年(2008年)岩手・宮城内陸地震?).[3]

This earthquake occurred in the south of the inland of Iwate Prefecture at 8:43 JST on Saturday morning, June 14 (23:43 UTC on June 13).[4] The JMA magnitude was estimated at Mj 7.2,[4] and the moment magnitude by USGS was at Mw 6.9.[5] The epicenter was located at 39°01.7′N 140°52.8′E / 39.0283°N 140.8800°E / 39.0283; 140.8800,[4] about 85 kilometres (55 mi) north of Sendai and about 385 kilometres (240 mi) north-northeast of Tokyo.[6]

The strongest shakings were measured in the cities of Ōshū (Iwate) and Kurihara (Miyagi), both of which were measured as "strong 6" on the Japan Meteorological Agency seismic intensity scale, shindo (震度 shindo?).[2] Peak ground acceleration readings were high, with a maximum vector sum (3 component) value of 4278 cm/s2 (4.36g).[7]

Seismic intensity[edit]

seismic intensity (震度 Shindo?) represents the strength of ground motion. JMA uses the scales of 0 to 7: 0, 1, 2, 3, 4, weak/strong 5, weak/strong 6, 7.

Prefecture Seismic intensities
Iwate 6+ 6- 5+ 5- 4 3 2
Miyagi 6+ 6- 5+ 5- 4 3
Akita 5+ 5- 4 3 2
Yamagata 5- 4 3 2
Fukushima 5- 4 3 2 1
Aomori 4 3 2 1
Ibaraki 4 3 2
Tochigi 4 3 2 1
Niigata 4 3 2 1
Hokkaidō 3 2 1
Gunma 3 2 1
Saitama 3 2 1
Chiba 3 2 1
Tokyo 3 2 1
Kanagawa 3 2 1
Yamanashi 3 2 1
Ishikawa 2 1
Nagano 2 1
Shizuoka 2 1
Aichi 1

Tremors were felt across a large area.[2]

Strongly shaken areas included:[2]

Strong 6:

Iwate Pref. - City of Ōshū (奥州市).
Miyagi Pref. - City of Kurihara (栗原市).

Weak 6:

Iwate Pref. - City of Ōshū (奥州市).
Miyagi Pref. - Cities of Kurihara (栗原市) and Ōsaki (大崎市).

Strong 5:

Iwate Pref. - Cities of Ōshū (奥州市), Kitakami (北上市), Ichinoseki (一関市), Towns of Kanegasaki (金ケ崎町) and Hiraizumi (平泉町).
Miyagi Pref. - Cities of Kurihara (栗原市), Ōsaki (大崎市), Sendai (仙台市), Tome (登米市), Natori (名取市), Towns of Misato (美里町), Wakuya (涌谷町), Kami (加美町), and Rifu (利府町).
Akita Pref. - City of Yuzawa (湯沢市), and Village of Higashinaruse (東成瀬村).

Tectonics[edit]

According to the USGS:[5]

The Mw 6.8 Honshu earthquake of June 13th 2008 occurred in a region of convergence between the Pacific Plate and the Okhotsk section of the North American Plate in northern Japan, where the Pacific plate is moving west-northwest with respect to North America at a rate of approximately 8.3 cm/yr. The hypocenter of the earthquake indicates shallow thrusting motion in the upper (Okhotsk) plate, above the subducting Pacific plate, which lies at approximately 80 km depth at this location.

The earthquake occurred in a region of upper-plate contraction, probably within the complicated tectonics of the Ou Backbone Range, known to have hosted several large earthquakes in historic times. The largest of these events occurred in 1896, approximately 70km north of the June 13th event, and killed over 200 people in the local area.

Aftershocks[edit]

According to JMA:[1][8][9]

Aftershocks of this earthquake were stronger than the Great Hanshin Earthquake in 1995, but they happened much less frequently.

Over 200 aftershocks were observed in the first 24 hours, with about 400 in total over the first seven days. The largest ones (with Mj5.0 or greater) were

June 14, 9:20: Mj5.7: Max. seismic intensity reached Strong 5;
June 14, 12:27: Mj5.2: Max. seismic intensity reached 4;
June 16, 23:14: Mj5.3: Max. seismic intensity reached 4.

From June 21 to July 1, four to 12 aftershocks were observed each day, with maximum seismic intensities of 3.

Subsequent earthquakes[edit]

The following is a list of earthquakes greater than 4.0 Mw that occurred in the five days following the 2008 Iwate earthquake. Aftershocks measured 6.0 Mw or over are in bold.

# Date Time Place Lat. Long. Fatalities Mw
June 13
Magnitude 6.9 - EASTERN HONSHU, JAPAN June 13, 2008 23:43:46 UTC Honshū, Japan (main earthquake) 39.103 140.668 10 + (12 missing) 6.9
June 14
[1] June 14, 2008 00:20:13 UTC Honshū, Japan 38.991 140.461 5.5
[2] June 14, 2008 00:52:43 UTC Honshū, Japan 39.139 140.792 4.7
[3] June 14, 2008 01:00:16 UTC Honshū, Japan 39.087 140.770 4.6
[4] June 14, 2008 01:39:48 UTC Honshū, Japan 39.107 140.819 4.7
[5] June 14, 2008 02:35:17 UTC Honshū, Japan 39.039 140.698 4.6
[6] June 14, 2008 03:10:32 UTC Honshū, Japan 39.145 140.736 4.8
[7] June 14, 2008 03:14:05 UTC Honshū, Japan 39.023 140.757 4.6
[8] June 14, 2008 03:27:34 UTC Honshū, Japan 39.255 140.710 5.0
[9] June 14, 2008 04:10:48 UTC Honshū, Japan 39.127 140.684 4.6
[10] June 14, 2008 05:39:08 UTC Honshū, Japan 39.320 140.727 4.5
[11] June 14, 2008 08:34:10 UTC Honshū, Japan 39.172 140.790 4.5
[12] June 14, 2008 10:11:57 UTC Honshū, Japan 38.907 140.707 4.5
[13] June 14, 2008 12:48:30 UTC Honshū, Japan 39.284 140.625 4.7
[14] June 14, 2008 14:42:33 UTC Honshū, Japan 39.092 140.745 5.1
[15] June 14, 2008 17:29:27 UTC Honshū, Japan 39.118 140.881 4.4
[16] June 14, 2008 18:29:22 UTC Honshū, Japan 39.221 140.739 4.5
[17] June 14, 2008 18:47:37 UTC Honshū, Japan 39.218 140.781 4.6
June 15
[18] June 15, 2008 03:30:02 UTC Honshū, Japan 39.168 140.870 4.6
June 16
[19] June 16, 2008 14:14:39 UTC Honshū, Japan 39.084 140.607 5.1
June 18
[20] June 18, 2008 09:04:34 UTC Honshū, Japan 39.156 140.863 4.8
Sources: "Earthquake List for 10-degree Map Centered at 40°N, 145°E". USGS. 2008-06-18. Retrieved 2008-06-18. 

Effects[edit]

External video
Original NHK broadcast of the earthquake warning on YouTube

Landslides[edit]

Landslides triggered by this earthquake crushed structures, buried people, cut off access to certain roads, and isolated some rural communities.[10] Mud from landslides dammed up rivers to form lakes called "quake lakes" (せき止め湖 sekitomeko?).[11]

By June 19, the Ministry of Land had identified fifteen quake lakes in Iwate and Miyagi prefectures,[12] and work crews began draining three of them which were at high risk of overflow or breach from rain or aftershocks.[13][14]

Human casualties[edit]

By 17:50 JST, June 25, twelve people were confirmed dead and 358 injured, and ten still missing.[15]

  • In City of Kurihara, Miyagi Pref., five people were buried in a landslide at a hot-spring inn called Komanoyu, which had stood on the mountainside of Mt. Kurikoma.[15][16] A woman aged 80 who had co-managed the inn with her husband, her 58 year-old son, a woman aged 75 who had worked at the inn, a 48 year-old tourism consultant, and an attendant of the Railway Museum aged 35 were all killed in the landslide.[17][18][19]
  • In the city of Kurihara, along Route 398, a landslide overwhelmed and killed three workers setting a rockfall containment net on a hillside.[15][20][21][22]
  • Also in the city of Kurihara, along Route 398, a 59 year-old man was killed when his car was carried away by a landslide and buried.[15][23]
  • At a dam construction site in the city of Ōshū, Iwate Pref., a worker aged 48 was struck by falling rocks and died.[15][20]
  • In the city of Ichinoseki, Iwate Pref., a person surprised by the tremor ran out into the road and was fatally struck by a truck.[15][20]
  • In the city of Iwaki, Fukushima Pref., near a fishing port, a person aged 55 was struck by falling rocks while fishing, fell into the sea, and drowned.[15][20]
  • In the city of Ōshū, a landslide caused a group of 20 people to become temporarily trapped in an overturned bus.[24] Eight of them were injured,[15] including one critically and five seriously.[25] The bus was running when overturned, and ten passengers escaped, prompted by the driver. Then an aftershock caused the bus to slip down slowly into a ravine until it was caught on some trees.[25] One of the passengers who had escaped walked down the road with a mobile phone until he was able to get a signal, and made an emergency call.[25]

Electric power supply[edit]

No nuclear power plants were shut down following this earthquake[26] unlike the 2007 Chūetsu offshore earthquake quake. Some water was found to have splashed out of a reaction container in the Fukushima II Nuclear Power Plant possibly due to the tremor, but no radioactive material was released to the environment.[26][27]

Expressways and railways[edit]

Expressways in Tōhoku region were closed in several sections, but all reopened by nighttime, barring traffic restrictions in one section for repair work.[28]

Some train services by JR East were suspended on Shinkansen and local lines, and resumed on the following day from the first scheduled trains.[29]

On Tōhoku Shinkansen, all running trains, about 20, were stopped by an earthquake detection system. Most were soon moved to the nearest stations.[30] However, about 2,000 passengers were temporarily trapped inside three trains[31] before being evacuated[30] up to nine and a half hours later,[32] because the trains were forced to stay in place while equipment inspections were carried out.[30]

Suspensions on Tōhoku, Akita, Yamagata Shinkansen and delays on Jōetsu, Nagano Shinkansen reportedly involved 117,000 passengers.[32] No trains derailed.[31]

References[edit]

  1. ^ a b "「平成20年(2008年)岩手・宮城内陸地震」の余震回数" (PDF). Japan Meteorological Agency. 2008-07-02. Retrieved 2 July 2008. As of 2008-07-02 ( 5:00 JST) .(Japanese)
  2. ^ a b c d Result of searching the database of felt earthquakes run by Japan Meteorological Agency.(Japanese) Archived 19 March 2011 at WebCite
  3. ^ "2008年6月14日08時43分ころの岩手県内陸南部の地震について(第2報)" (in Japanese). Japan Meteorological Agency. 2008-06-14. Archived from the original on 2011-03-19. Retrieved 2008-06-14. 
  4. ^ a b c "「平成20年(2008年)岩手・宮城内陸地震」について(第4報)" (in Japanese). Japan Meteorological Agency. 2008-06-14. Archived from the original on 2011-03-19. Retrieved 2008-06-18. 
  5. ^ a b "Magnitude 6.9 - EASTERN HONSHU, JAPAN". U.S. Geological Survey. 2008-06-14. Retrieved 18 June 2008. Retrieved on 2008-06-18 (10:30 UTC).(English)
  6. ^ Calculation tool: "距離と方位角の計算", offered by Geographical Survey Institute. Retrieved on 2008-06-18.(Japanese)
  7. ^ Masumi Yamada et al (July–August 2010). "Spatially Dense Velocity Structure Exploration in the Source Region of the Iwate-Miyagi Nairiku Earthquake". Seismological Research Letters v. 81; no. 4;. Seismological Society of America. pp. 597–604. Retrieved 21 March 2011. 
  8. ^ "「平成20 年(2008 年)岩手・宮城内陸地震」について(第8報)" (PDF) (in Japanese). Japan Meteorological Agency. 2008-06-23. Retrieved 2008-07-01. 
  9. ^ "「平成20 年(2008 年)岩手・宮城内陸地震」について(第9報)" (PDF) (in Japanese). Japan Meteorological Agency. 2008-06-26. Retrieved 2008-07-01. 
  10. ^ "岩手・宮城内陸地震:6人死亡、155人負傷 不明11人". THE MAINICHI NEWSPAPERS. 2008-06-14. Retrieved 20 June 2008. Last updated on 2008-06-15 (9:55 JST).(Japanese)
  11. ^ "Rush to drain 'quake lakes' in Tohoku". Mainichi Daily News. 2008-06-17. Retrieved 2008-06-19. [dead link]
  12. ^ "平成20年岩手・宮城内陸地震により発生した河道閉塞(天然ダム)箇所について" (in Japanese). Ministry of Land, Infrastructure, Transport and Tourism. 2008-06-19. Archived from the original on 28 June 2008. Retrieved 2008-06-19. 
  13. ^ (This article will remain less than a month.) "Water being pumped out of quake lakes". NHK. 2008-06-19. Retrieved 2008-06-19. 
  14. ^ "宮城 せき止め湖仮排水路工事" (in Japanese). NHK. 2008-06-19. Retrieved 2008-06-19. 
  15. ^ a b c d e f g h "平成20年(2008年)岩手・宮城内陸地震(第51報)" (PDF). Fire and Disaster Management Agency. 2008-06-25. Retrieved 25 June 2008. As of 2008-06-25 (17:50 JST).(Japanese)
  16. ^ "秘湯の宿、瓦礫からうめき声…「駒ノ湯温泉」捜索難航" (in Japanese). The Yomiuri Shimbun. 2008-06-15. Archived from the original on 2008-06-18. Retrieved 2008-06-21. 
  17. ^ "鉄道愛し、地域に尽くした 駒の湯温泉宿泊者" (in Japanese). The Asahi Shimbun Company. 2008-06-15. Archived from the original on 18 June 2008. Retrieved 2008-06-21. 
  18. ^ "男性遺体は経営者の長男 駒の湯温泉" (in Japanese). The Asahi Shimbun Company. 2008-06-17. Archived from the original on 20 June 2008. Retrieved 2008-06-21. 
  19. ^ "旅館手伝い女性の遺体を発見 駒の湯温泉で捜索隊" (in Japanese). The Asahi Shimbun Company. 2008-06-18. Archived from the original on 18 June 2008. Retrieved 2008-06-21. 
  20. ^ a b c d "岩手・宮城地震 死者6人、行方不明11人に" (in Japanese). The Asahi Shimbun Company. 2008-06-14. Archived from the original on 17 June 2008. Retrieved 2008-06-21. 
  21. ^ "作業員3人生き埋め 2人の死亡確認 栗原市花山" (in Japanese). The Asahi Shimbun Company. 2008-06-14. Archived from the original on 17 June 2008. Retrieved 2008-06-21. 
  22. ^ "1遺体発見 死者12人・不明10人に 岩手・宮城地震" (in Japanese). The Asahi Shimbun Company. 2008-06-21. Archived from the original on 4 August 2008. Retrieved 2008-06-21. 
  23. ^ "対面の親族「実感ない」 湯浜温泉近くで死亡の男性" (in Japanese). The Asahi Shimbun Company. 2008-06-15. Archived from the original on 18 June 2008. Retrieved 2008-06-21. 
  24. ^ "Japanese quake leaves at least six dead". United Press International, Inc. 2008-06-14. Retrieved 2008-06-19. 
  25. ^ a b c "岩手・宮城内陸地震:バスが沢に転落、1人重体 奥州市". THE MAINICHI NEWSPAPERS. 2008-06-14. Retrieved 20 June 2008. Last updated on 2008-06-14 (21:04 JST).(Japanese)
  26. ^ a b "平成20年岩手・宮城内陸地震被害情報(第8報)(6月14日17時00現在)" (PDF). Nuclear and Industrial Safety Agency, Ministry of Economy, Trade and Industry. 2008-06-14. Archived from the original on 24 June 2008. Retrieved 20 June 2008. As of 2008-06-14 (17:00 JST).(Japanese)
  27. ^ "岩手・宮城内陸地震:原発で水漏れ 外部に影響なし" (in Japanese). THE MAINICHI NEWSPAPERS. 2008-06-15. Retrieved 2008-06-20. [dead link]
  28. ^ "平成20年 岩手・宮城内陸地震で発生した高速道路の被害状況等について(第8報 最終)" (in Japanese). East Nippon Expressway Company Limited. 2008-06-14. Retrieved 2008-06-18. 
  29. ^ "岩手・宮城地震:15日始発からすべて運行…JR東日本". THE MAINICHI NEWSPAPERS. 2008-06-15. Retrieved 18 June 2008. Last updated on 2008-06-15 (21:05 JST).(Japanese)
  30. ^ a b c "【岩手・宮城内陸地震】「脱線せず」はJRの対策が奏功か 震源からの距離も影響?" (in Japanese). The Sankei Shimbun. 2008-06-14. Archived from the original on 2008-06-19. Retrieved 2008-06-18. 
  31. ^ a b "2,000 passengers trapped in bullet trains, 20,000 households lose power after quake". Mainichi Daily News. 2008-06-14. Retrieved 2008-06-18. [dead link]
  32. ^ a b "岩手・宮城内陸地震:新幹線に9時間半閉じ込め 道路寸断". THE MAINICHI NEWSPAPERS. 2008-06-14. Retrieved 18 June 2008. Last updated on 2008-06-15 (0:27 JST).(Japanese)