Powerful Magnitude 7.0 Earthquake Rocks Japan, Touches Off Small Tsunami
December 7, 2012

Powerful Magnitude 7.3 Earthquake Rocks Japan, Touches Off Small Tsunami

Lawrence LeBlond for redOrbit.com - Your Universe Online

Japan, still reeling with the aftermath of a powerful earthquake and destructive tsunami in March 2011, has been hit again. A magnitude 7.3 earthquake struck off the coast at 5:18 p.m. local time Friday evening triggering a small 3-foot-high tsunami that swept against the Japanese mainland nearly 45 minutes later. Evacuation orders came streaming in over TV and radio channels shortly after the quake struck and countless coastal residents heeded the warnings and fled to higher grounds.

"We are now calling on people to evacuate to higher ground," Ryuichi Omori, an official in Ishinomaki, told AFP. "It's already pitch dark here. Calls phones - both landlines and mobiles - are not going through now, which makes it difficult to see people's movement.

"The quake was not so big although it felt very (strong). It was not big at all compared with last year's earthquake. The town office is now setting up a disaster taskforce," Omori explained.

While the quake rattled office windows and shook buildings, it was nowhere near as powerful as last year´s 9.0 earthquake that rocked areas of the island nation, touching of a deadly tsunami that inundated coastal communities, killing thousands and destroying one the country´s nuclear power plants, causing further devastation to the region and abroad.

No injuries had been reported with the latest quake, and no reports of death or damage followed the tsunami, which hit Ishinomaki in the Miyagi Prefecture. Miyagi was one of the areas that suffered the worst damage following the March 2011 earthquake and tsunami. The epicenter of Friday´s quake was about 287 miles southeast of Kamiashi at a relatively shallow depth of about 22 miles, according to the US Geological Service (USGS).

Shortly after the first tsunami rolled into coastal communities the Pacific Tsunami Warning Center said there was no further risk of a widespread tsunami and subsequently dropped all tsunami warnings for the region.

Train services were suspended in the region while officials conducted safety checks; aircraft scheduled to land at Sendai Airport were diverted to other airports for precaution. An operator at Fukushima nuclear plant reported that the quake had no impact on efforts to restore operations at the plant, crippled in last year´s devastating quake. Emergency teams that had been working at the plant were ordered to evacuate as a precautionary measure, but returned shortly after.

Residents in the affected regions were taking photos of their TV screens issuing tsunami warnings and posting them on Facebook, asking each other whether they were safe, and confirming their whereabouts.

Shortly before the quake struck, NHK television broke off regular programming to warn that a strong temblor was imminent. After it hit, the announcer repeatedly urged all coastal resident to seek higher ground.

The Japanese media responded much more quickly and aggressively to the latest quake than they had in the past, Adam Ezard, a British expatriate living in Tokyo, told CBSNews.com. He said nearly all channels broke from programming and issued warnings, with NHK giving information in multiple languages for the first time.

Reports of the potential size of a tsunami following the initial tremor were varied, with measurements given from between 20 inches and 7 feet.

But any of these measurements would have represented a far lower risk of devastation than last year´s 36-foot wall of water that inundated coastal Japan, said BBC´s Rupert Wingfield Hayes. He noted that despite this, the country is clearly going to take all precautions no matter what the size of the quake is–especially after losing more than 16,000 lives in March 2011´s tragedy.

John Heritage, an English teacher in Miyagi Prefecture, said Friday´s earthquake was not as strong as some he had experienced in the past but maintained it was worrisome as it went on for a longer period–nearly 7 minutes.

"The students were kind of worried. Normally they're pretty calm, but they looked concerned. Then the tsunami alarm started going off and we evacuated to higher ground," he told the BBC.

The USGS said Friday´s quake occurred as a result of reverse faulting within the ocean lithosphere of the Pacific plate, roughly 12 miles east of the plate boundary between the Pacific and North America plates that marks the location where the Pacific subducts beneath Japan. At the epicenter of this temblor, the Pacific plate moves west-northwest with respect to the North America plate at a velocity of about 3.2 inches per year.

The plate boundary region surrounding this latest earthquake hosts moderate to large earthquakes on a regular basis–12 events of a magnitude 7.0 or larger have occurred within 150 miles of this one over the past 40 years. This includes last year´s 9.0 mega-quake that devastated parts of Japan. That quake ruptured a large portion of the subduction zone plate interface to the west of Friday´s event. The 2011 mega-thrust event also kicked off a series of aftershocks east of the plate boundary within the pacific plate, which includes a magnitude 7.6 normal faulting earthquake 36 miles to the northeast of the December 7, 2012 tremor, according to information on the USGS website.