Tsunami warning issued after Japan hit by 2 big earthquakes
December 7, 2012 in Outdoors
tsunami warning issued after Japan hit
by 2 earthquakes
A tsunami warning has been issued after a 7.3 magnitude earthquake struck off Japan’s eastern coast.
The epicentre of the quake was about 245km (150 miles) south-east of Kamiashi at a depth of about 36km, the US Geological Survey said.
The quake was felt in the capital Tokyo, media report.
The tsunami warning was issued for the coast of Miyagi Prefecture, which was hit by a devastating earthquake and tsunami in March 2011.
The US-based Pacific Tsunami Warning Center said there was no threat to the wider Pacific Ocean but that a tsunami could be generated that was destructive for local coastlines.
Warnings of the tsunami height varied between 50cm and 2m.
Evacuations have been ordered from some of the affected areas.
Buildings were reported to have swayed in Tokyo for several minutes
a second earthquake hit japan 13 minutes after the first with a magnitude of 6.2 218km SE of Ofunato, Japan.
A one-metre wave hit Ishinomaki in Miyagi Prefecture and many people heeded calls to move to higher ground before all alerts were later lifted.
The quake epicentre was about 245km (150 miles) south-east of Kamiashi at a depth of about 36km, the US Geological Survey said.
Miyagi was hit by a devastating earthquake and tsunami in March 2011.
The US-based Pacific Tsunami Warning Center had said there was no threat to the wider Pacific Ocean but had warned a local tsunami could be destructive for local coastlines.
There have been no reports of deaths or injuries, and all tsunami warnings were cancelled at 19:20 local time a broadcaster from NHK said.
M7.3-245km SE of Kamaishi, Japan 2012-12-07 08:18:24 UTC
Legend-Epicenter-Nearby City-Faults-Plate Boundaries
- 2012-12-07 08:18:24 UTC
- 2012-12-07 18:18:24 UTC+10:00 at epicenter
- 2012-12-07 09:18:24 UTC+01:00 system time
37.889°N 144.090°E depth=36.1km (22.4mi)
- 245km (152mi) SE of Kamaishi, Japan
- 245km (152mi) ESE of Ofunato, Japan
- 251km (156mi) ESE of Ishinomaki, Japan
- 251km (156mi) SE of Otsuchi, Japan
- 462km (287mi) ENE of Tokyo, Japan
Seismotectonics of Japan and Vicinity
Japan and the surrounding islands straddle four major tectonic plates: Pacific plate; North America plate; Eurasia plate; and Philippine Sea plate. The Pacific plate is subducted into the mantle, beneath Hokkaido and northern Honshu, along the eastern margin of the Okhotsk microplate, a proposed subdivision of the North America plate. Farther south, the Pacific plate is subducted beneath volcanic islands along the eastern margin of the Philippine Sea plate. This 2,200 km-long zone of subduction of the Pacific plate is responsible for the creation of the deep offshore Ogasawara and Japan trenches as well as parallel chains of islands and volcanoes, typical of Circumpacific island arcs. Similarly, the Philippine Sea plate is itself subducting under the Eurasia plate along a zone, extending from Taiwan to southern Honshu that comprises the Ryukyu Islands and the Nansei-Shoto trench.
Subduction zones at the Japanese island arcs are geologically complex and produce numerous earthquakes from multiple sources. Deformation of the overriding plates generates shallow crustal earthquakes, whereas slip at the interface of the plates generates interplate earthquakes that extend from near the base of the trench to depths of 40 to 60 km. At greater depths, Japanese arc earthquakes occur within the subducting Pacific and Philippine Sea plates and can reach depths of nearly 700 km. Since 1900, three great earthquakes occurred off Japan and three north of Hokkaido. They are the M8.4 1933 Sanriku-oki earthquake, the M8.3 2003 Tokachi-oki earthquake, the M9.0 2011 Tohoku earthquake, the M8.4 1958 Etorofu earthquake, the M8.5 1963 Kuril earthquake, and the M8.3 1994 Shikotan earthquake.