08-13-2009, 11:14 PM
Eastern Japan has been hit by a third strong earthquake in less than a week, prompting speculation that the recent underground activity may be the precursor to a massive - and overdue - tremor in the Tokai region.
By Julian Ryall in Tokyo
Published: 3:08AM BST 13 Aug 2009
The earthquake had a magnitude of 6.5 and originated 40 km below the surface of the sea off Hachijo Island, south of Tokyo. The tremor on Tuesday morning, in which a woman was killed when a bookcase collapsed on her and 110 people were injured, was a short way to the west.
The earthquake, also measuring 6.5, was the largest in Shizuoka Prefecture since 1944 and forced the emergency shut-down of two nuclear reactors, caused a 60 cm tsunami to hit local beaches and damaged road and rail links.
But officials of the Japan Meteorological Agency said the tremors are not indicators of the quake that the region has been bracing itself for over the last 20 years.
Major movements in the crust of the Earth have occurred in the Tokai region, close to the major city of Nagoya, on average every 110 years. The last one with a magnitude of 8 was 155 years ago.
Researchers now put the likelihood of a serious earthquake - one that could cause around 6,000 deaths, 20,000 serious injuries and damage to 1 million buildings - within the next 30 years as high as 87 per cent.
"Old records show that there have been a series of gigantic quakes in this area," said Yohei Hasegawa, a spokesman for the agency's Earthquake and Tsunami Observation Division.
"In some cases, we know there are precursors and we hope that the early-warning system that was introduced in October 2007 will be able to give local people up to 20 seconds to prepare," he said.
Made up of a series of sensitive strain meters, seismographs and tilt meters, the warning system failed to issue a warning for any of the recent quakes because the energy emitted by a precursor wave was too small to be picked up, Hasegawa said.
"The quake on Tuesday was 6.5 and while in other countries that might be considered quite big, it was not so serious here in Japan," he said.
"If we could detect the precursors of smaller earthquakes, that would be ideal, but I don't think it's practical at the moment," he said. "This is a very difficult science and I have never heard of a researcher claiming to be able to detect a precursor to such a small earthquake."
Meanwhile, the government has been forced to downplay the failure of its early-warning alarm system, which did not detect Tuesday's quake.
http://www.telegraph.co.uk/news/worldnew...quake.html
By Julian Ryall in Tokyo
Published: 3:08AM BST 13 Aug 2009
The earthquake had a magnitude of 6.5 and originated 40 km below the surface of the sea off Hachijo Island, south of Tokyo. The tremor on Tuesday morning, in which a woman was killed when a bookcase collapsed on her and 110 people were injured, was a short way to the west.
The earthquake, also measuring 6.5, was the largest in Shizuoka Prefecture since 1944 and forced the emergency shut-down of two nuclear reactors, caused a 60 cm tsunami to hit local beaches and damaged road and rail links.
But officials of the Japan Meteorological Agency said the tremors are not indicators of the quake that the region has been bracing itself for over the last 20 years.
Major movements in the crust of the Earth have occurred in the Tokai region, close to the major city of Nagoya, on average every 110 years. The last one with a magnitude of 8 was 155 years ago.
Researchers now put the likelihood of a serious earthquake - one that could cause around 6,000 deaths, 20,000 serious injuries and damage to 1 million buildings - within the next 30 years as high as 87 per cent.
"Old records show that there have been a series of gigantic quakes in this area," said Yohei Hasegawa, a spokesman for the agency's Earthquake and Tsunami Observation Division.
"In some cases, we know there are precursors and we hope that the early-warning system that was introduced in October 2007 will be able to give local people up to 20 seconds to prepare," he said.
Made up of a series of sensitive strain meters, seismographs and tilt meters, the warning system failed to issue a warning for any of the recent quakes because the energy emitted by a precursor wave was too small to be picked up, Hasegawa said.
"The quake on Tuesday was 6.5 and while in other countries that might be considered quite big, it was not so serious here in Japan," he said.
"If we could detect the precursors of smaller earthquakes, that would be ideal, but I don't think it's practical at the moment," he said. "This is a very difficult science and I have never heard of a researcher claiming to be able to detect a precursor to such a small earthquake."
Meanwhile, the government has been forced to downplay the failure of its early-warning alarm system, which did not detect Tuesday's quake.
http://www.telegraph.co.uk/news/worldnew...quake.html