The occurred off the coast of

Miyagi Prefecture is a prefecture of Japan located in the Tōhoku region of Honshu. Miyagi Prefecture has a population of 2,305,596 (1 June 2019) and has a geographic area of . Miyagi Prefecture borders Iwate Prefecture to the north, Akita Prefecture to the nor ...

, approximately east of

Sendai, Japan is the capital city of Miyagi Prefecture, the largest city in the Tōhoku region. , the city had a population of 1,091,407 in 525,828 households, and is one of Japan's 20 designated cities. The city was founded in 1600 by the ''daimyō'' Date M ...

. The thrust earthquake was classified as an

aftershock In seismology, an aftershock is a smaller earthquake that follows a larger earthquake, in the same area of the main shock, caused as the displaced crust adjusts to the effects of the main shock. Large earthquakes can have hundreds to thousand ...

of the March 11 Tōhoku earthquake, and occurred at 23:32 JST (14:32 UTC) on Thursday, 7 April 2011. Several tsunami warnings were issued for the northeastern coast of

Honshu , historically called , is the largest and most populous island of Japan. It is located south of Hokkaidō across the Tsugaru Strait, north of Shikoku across the Inland Sea, and northeast of Kyūshū across the Kanmon Straits. The island separat ...

; however, they were all canceled 90 minutes later. Over 3 million households in the area were left without power, and several nuclear plants suffered minor malfunctions. There was no major structural damage, but the quake killed at least 4 people and injured 141.

Earthquake

The

submarine earthquake A submarine, undersea, or underwater earthquake is an earthquake that occurs underwater at the bottom of a body of water, especially an ocean. They are the leading cause of tsunamis. The magnitude can be measured scientifically by the use of the ...

occurred at a

focal depth In seismology, the depth of focus or focal depth refers to the depth at which an earthquake occurs. Earthquakes occurring at a depth of less than are classified as shallow-focus earthquakes, while those with a focal depth between and are commonl ...

of 49 km (30.4 mi) in the western

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contin ...

on 7 April 2011 at 14:21 UTC, approximately 66 km (41 mi) east of

Sendai is the capital city of Miyagi Prefecture, the largest city in the Tōhoku region. , the city had a population of 1,091,407 in 525,828 households, and is one of Japan's 20 designated cities. The city was founded in 1600 by the ''daimyō'' Date M ...

. The quake was a direct result of

thrust fault A thrust fault is a break in the Earth's crust, across which older rocks are pushed above younger rocks. Thrust geometry and nomenclature Reverse faults A thrust fault is a type of reverse fault that has a dip of 45 degrees or less. If ...

ing on or near the

subduction zone Subduction is a geological process in which the oceanic lithosphere is Geochemical cycle, recycled into the Earth's mantle at convergent boundary, convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less d ...

plate boundary Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large te ...

between the

Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

and

North American Plate The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Pacifi ...

s. 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 Megathrust earthquakes occur at convergent plate boundaries, where one tectonic plate is forced underneath another. The earthquakes are caused by slip along the thrust fault that forms the contact between the two plates. These interplate earthqu ...

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.

Damage and casualties

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 the epicentre. Upon the detection of the earthquake, the

Japan Meteorological Agency The , abbreviated JMA, is an agency of the Ministry of Land, Infrastructure, Transport and Tourism. It is charged with gathering and providing results for the public in Japan that are obtained from data based on daily scientific observation an ...

issued a tsunami warning for Miyagi Prefecture, as well as tsunami alerts for

Iwate Prefecture is a prefecture of Japan located in the Tōhoku region of Honshu. It is the second-largest Japanese prefecture at , with a population of 1,210,534 (as of October 1, 2020). Iwate Prefecture borders Aomori Prefecture to the north, Akita Prefect ...

Fukushima Prefecture Fukushima Prefecture (; ja, 福島県, Fukushima-ken, ) is a Prefectures of Japan, prefecture of Japan located in the Tōhoku region of Honshu. Fukushima Prefecture has a population of 1,810,286 () and has a geographic area of . Fukushima Pref ...

Aomori Prefecture is a prefecture of Japan in the Tōhoku region. The prefecture's capital, largest city, and namesake is the city of Aomori. Aomori is the northernmost prefecture on Japan's main island, Honshu, and is bordered by the Pacific Ocean to the eas ...

Ibaraki Prefecture is a prefecture of Japan located in the Kantō region of Honshu. Ibaraki Prefecture has a population of 2,871,199 (1 June 2019) and has a geographic area of . Ibaraki Prefecture borders Fukushima Prefecture to the north, Tochigi Prefecture ...

and the

Pacific Rim The Pacific Rim comprises the lands around the rim of the Pacific Ocean. The '' Pacific Basin'' includes the Pacific Rim and the islands in the Pacific Ocean. The Pacific Rim roughly overlaps with the geologic Pacific Ring of Fire. List of ...

. 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. The tremor caused widespread power outages, with power still not restored to some 3.6 million households across several prefectures by 8 April. 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. 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. 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 further damage from this quake. Four people were reported dead as a result of the earthquake, including an elderly woman in

Yamagata Prefecture is a prefecture of Japan located in the Tōhoku region of Honshu. Yamagata Prefecture has a population of 1,079,950 (1 June 2019) and has a geographic area of 9,325 km² (3,600 sq mi). Yamagata Prefecture borders Akita Prefecture to the north ...

who lost power to her medical ventilator. An additional 141 people suffered minor injuries, ranging from cuts and bruises to bone fractures. No major losses were reported, though some roads sustained damage, as well as a few homes. The Nikkei index fell sharply at the close of trading, but rebounded the next day when reports of limited damage were confirmed.

References

External links

* {{Earthquakes in Japan Earthquakes of the Heisei period April 2011 events in Japan 2011 earthquakes 2011 disasters in Japan 2011 in Japan

Earthquake

Damage and casualties

See also

References

External links