Signs of three major Japan quakes before 2011

Apr 25, 2012
A bus was removed from the roof of a building in Ishinomaki on the day after the March 11 earthquake-tsunami disaster. A team of scientists annouced Wednesday that three major earthquakes seem to have hit northern Japan before the disaster.

Three major earthquakes seem to have occurred in northern Japan before it was hit in March 2011 by a massive quake and tsunami, researchers said Wednesday based on new evidence.

The findings by Swiss, German and , which could have a significant impact on future , were presented at the annual conference of the European Geosciences Union in Vienna.

"We were able to get a record of at least three major sedimentary remobilisation events that potentially suggest the occurrence of previous large potentially 2011 Tohoku-type earthquakes," Michael Strasser, a geologist from the Swiss Federal Institute of Technology (ETH) Zurich, told journalists.

"In theory, it might not be an earthquake because you can trigger large scale resedimentation also by other processes, but at this stage, it's the most likely explanation."

The researchers launched an underwater mission in the off the northeastern coast of Japan in March, using a special vehicle equipped with cameras and going to depths of up to 7,700 metres (25,260 feet).

They were now further analysing the samples to date these mooted earthquakes.

"Once we get the age of these events, that will be an important contribution to hazard assessments because if you want to calculate the probability of the occurence of earthquakes, you should know your occurence pattern," said Strasser.

Historic sources already mention a major tremor in the same region some 1,300 years ago.

The research mission also mapped out the seabed around the of the 9.0-magnitude quake that hit Japan on March 11, 2011, triggering a massive tsunami and a meltdown at the Fukushima nuclear plant, killing some 19,000 people.

Comparisons with measures taken before the quake confirmed with more precision data obtained by other means in March 2011, which showed that parts of the seabed moved up to 50 metres sideways near the following the tremor, while an area of 15,000 square kilometres (5,790 square miles) rose by five metres.

Explore further: NASA balloons begin flying in Antarctica for 2014 campaign

add to favorites email to friend print save as pdf

Related Stories

Scientists survey seabed fractured by Japan quake

Mar 08, 2012

Scientists on Thursday launched a mission to the seabed off Japan where a massive quake triggered last year's devastating tsunami, to get their first proper look at the buckled ocean floor.

Japan's mega-quake struck in small zone of fault: study

Jun 15, 2011

The deadly 9.0-magnitude quake that struck off northeastern Japan on March 11 ruptured a relatively small part of a notorious fault that straddles the Pacific seabed, Japanese scientists reported on Wednesday.

Geological evidence for past earthquakes in Tokyo region

Jan 31, 2012

In 1923, a magnitude 7.9 earthquake devastated the Tokyo area, resulting in more than 100,000 deaths. About 200 years earlier, in 1703, a magnitude 8.2 earthquake struck the same region, causing more than 10,000 deaths.

Rapid tsunami warning by means of GPS

Apr 25, 2012

For submarine earthquakes that can generate tsunamis, the warning time for nearby coastal areas is very short. Using high-precision analysis of GPS data from the Fukushima earthquake of 11 March 2011, scientists ...

No long-distance risks from mega-quakes: study

Mar 27, 2011

Monster earthquakes like the 9.0-magnitude event that occurred off Japan on March 11 are unlikely to trigger a large quake in distant regions of the world, according to a study published on Sunday.

Recommended for you

Strong quake hits east Indonesia; no tsunami threat

34 minutes ago

A strong earthquake struck off the coast of eastern Indonesia on Sunday evening, but there were no immediate reports of injuries or damage, and authorities said there was no threat of a tsunami.

Scientists make strides in tsunami warning since 2004

Dec 19, 2014

The 2004 tsunami led to greater global cooperation and improved techniques for detecting waves that could reach faraway shores, even though scientists still cannot predict when an earthquake will strike.

Trade winds ventilate the tropical oceans

Dec 19, 2014

Long-term observations indicate that the oxygen minimum zones in the tropical oceans have expanded in recent decades. The reason is still unknown. Now scientists at the GEOMAR Helmholtz Centre for Ocean Research ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.