April 2011 Miyagi earthquake

The April 2011 Miyagi earthquake (Japanese: "2011 Miyagi Prefecture earthquake" (2011年 宮城県沖地震, 2011-Nen Miyagi-ken-oki jishin)) occurred off the coast of Miyagi Prefecture, approximately 66 kilometres (41 mi) east of Sendai, Japan. The Mw  7.1 thrust earthquake was classified as an aftershock of the March 11 Tōhoku earthquake, and occurred at 23:32 JST (14:32 UTC) on Thursday, 7 April 2011.

April 2011 Miyagi earthquake
2011年 宮城県沖地震
April 2011 Miyagi earthquake is located in Japan
April 2011 Miyagi earthquake
11 March quake
11 March quake
UTC time2011-04-07 14:32:44
ISC event16413596
Local date7 April 2011 (2011-04-07)
Local time23:32 JST
Magnitude7.1 Mw [1]
Depth49 km (30 mi)
Epicenter38°15′11″N 141°38′24″E / 38.253°N 141.640°E / 38.253; 141.640Coordinates: 38°15′11″N 141°38′24″E / 38.253°N 141.640°E / 38.253; 141.640
Areas affectedJapan
Max. intensityVIII (Severe) [2]
Casualties4 confirmed dead, 141 injured[3]

Several tsunami warnings were issued for the northeastern coast of Honshu; however, they were all canceled 90 minutes later.[4] Over 3 million households in the area were left without power, and several nuclear plants suffered minor inconveniences. There was no major structural damage, but the quake killed at least 4 people and injured 141.[5]


The Mw  7.1 submarine earthquake occurred at a focal depth of 49 km (30.4 mi) in the western Pacific Ocean on 7 April 2011 at 14:21 UTC, approximately 66 km (41 mi) east of Sendai. The quake was a direct result of thrust faulting on or near the subduction zone plate boundary between the Pacific and North American Plates. Initially estimated at a magnitude of 7.4, the tremor was felt in several areas near the east coast of Honshu as an aftershock of the 11 March magnitude 9.0 megathrust Tōhoku earthquake. The aftershock sequence of this event is ongoing since 11 March, and includes over 58 earthquakes of magnitude 6.0 or greater up until 7 April 2011, with only two others of magnitude 7.0 or greater.[1]

Damage and casualtiesEdit

Although the quake was located several miles offshore, moderate to very strong shaking was reported as far inland as Tokyo, about 333 km (207 mi) from its epicentre.[6] Upon the detection of the earthquake, the Japan Meteorological Agency issued a tsunami warning for Miyagi Prefecture, as well as tsunami alerts for Iwate Prefecture, Fukushima Prefecture, Aomori Prefecture, Ibaraki Prefecture and the Pacific Rim. Waves of between 0.5 and 1 m were anticipated, and residents along coastal areas were urged to evacuate. All warnings and alerts were canceled within 90 minutes, however.[7] The tremor caused widespread power outages, with power still not restored to some 3.6 million households across several prefectures by 8 April.[8] Nuclear power plants within the region also suffered from the outages; two of three power lines supplying power to fuel coolers were cut off at the Onagawa power plant.[9] Radioactive water consequently leaked out of spent fuel pools at three of its reactors, though no change in the radiation levels outside the plant was reported.[10] Five coal-powered power plants also shut down, adding to concerns over energy shortages. Fukushima I power plant, which had earlier been struck by the 11 March quake, evacuated its workers as a safety precaution, but the plant sustained no damage.[8]

Four people were reported dead as a result of the earthquake, including an elderly woman in Yamagata Prefecture who lost power to her medical ventilator.[3] An additional 141 people suffered minor injuries, ranging from cuts and bruises to bone fractures.[9] No major losses were reported, though some roads sustained damage, as well as a few homes.[11] The Nikkei index fell sharply at the closing but rebounded the next day when reports of limited damage were confirmed.[12][13]

See alsoEdit


  1. ^ a b "Magnitude 7.1 – NEAR THE COAST OF HONSHU, JAPAN". earthquake.usgs.gov. USGS. 7 April 2011. Archived from the original on 14 April 2011. Retrieved 2011-04-09.
  2. ^ "PAGER – M 7.1 – NEAR THE EAST COAST OF HONSHU, JAPAN". earthquake.usgs.gov. USGS. 7 April 2011. Retrieved 2011-04-20.
  3. ^ a b Staff Writer (8 April 2011). "4 killed, 141 injured after 7.4 quake hits Miyagi Pref, vicinity". Japan Today. Retrieved 2011-04-08.
  4. ^ Rubinsky, Cara (7 April 2011). "Japan lifts new tsunami warning after 7.4 quake". Associated Press. Retrieved 2011-04-08.
  5. ^ Cooper, Hayden (April 8, 2011). "Japan aftershock kills four, dozens injured". radioaustralianews.au.net. ABC Radio Australia News. Retrieved 2011-04-08.
  6. ^ Staff Writer (7 April 2011). "Japan Earthquake Today: Minor Damages, Nuclear Plane Intact". International Business Times. Retrieved 2011-04-08.
  7. ^ "Japan's Meteorological Agency lifted a tsunami warning". ytwhw.com. 8 April 2011. Archived from the original on 22 March 2012. Retrieved 2011-04-08.
  8. ^ a b Tabuchi, Hiroko (9 April 2011). "Aftershock hits Japan, knocks out power at nuclear plants". theage.com.au. The Age. Retrieved 2011-04-09.
  9. ^ a b Stanglin, Douglas (7 April 2011). "New quake disrupts power to cooling unit at nuclear plant". content.usatoday.com. USA Today. Retrieved 2011-04-09.
  10. ^ Staff Writer (8 April 2011). "Japan's Onagawa Nuclear Plant Loses Power in Latest Quake". ens-newswire.com. Environment News Service. Retrieved 2011-04-09.
  11. ^ CNN Wire Staff (8 April 2011). "Fresh aftershock in Japan rouses fear, kills 2". edition.cnn.com. CNN. Retrieved 2011-04-17.
  12. ^ Staff Writer (8 April 2011). "More Japan Stocks Drop After Magnitude 7.1". SFGate. Retrieved 2011-04-09.
  13. ^ Xinhua News Agency (2011-04-08). "Roundup: Nikkei climbs 1.85 pct as damage from latest quake minimal". China Daily. Retrieved 11 April 2011.

External linksEdit