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.
Several tsunami warnings were issued for the
northeastern coast of Honshu; 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 inconveniences.
There was no major structural damage, but
the quake killed at least 4 people and injured
141.
== Earthquake ==
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.
== 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 its epicentre.
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.
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 damage.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.
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 closing
but rebounded the next day when reports of
limited damage were confirmed.
== See also ==
List of earthquakes in 2011
List of earthquakes in Japan
