Powerboat-World.com
 
 
News Home Video Gallery Newsletters FishingBoating Features Photo Gallery Sail-World Australia Australian Cruising
Sail-World Australia Australian Cruising MarineBusiness-World

 

Sail-World.com : Japan earthquake looks to increase quake risk elsewhere in the country

Japan earthquake looks to increase quake risk elsewhere in the country

'Map showing the 11 March 2011 magnitude 9.0 off Tohoku mainshock and 166 aftershocks of magnitude 5.5 and greater until May 20. Warmer color indicates more recent events. Larger symbol indicates greater quake magnitude.'    Woods Hole Oceanographic Institution (WHOI) ©

Japan’s recent magnitude 9.0 earthquake, which triggered a devastating tsunami, relieved stress along part of the quake fault but also has contributed to the build up of stress in other areas, putting some of the country at risk for up to years of sizeable aftershocks and perhaps new main shocks, scientists say.

After studying data from Japan’s extensive seismic network, researchers from the Woods Hole Oceanographic Institution (WHOI), Kyoto University and the U.S. Geological Survey (USGS) have identified several areas at risk from the quake, Japan’s largest ever, which already has triggered a large number of aftershocks.

Data from the magnitude 9.0 Tohoku earthquake on March 11 has brought scientists a small but perceptible step closer to a better assessment of future seismic risk in specific regions, said Shinji Toda of Kyoto University, a lead author of the study. 'Even though we cannot forecast precisely, we can explain the mechanisms involved in such quakes to the public,' he said. Still, he added, the findings do bring scientists 'a little bit closer' to being able to forecast aftershocks.

'Research over the past two decades has shown that earthquakes interact in ways never before imagined,' Toda, Jian Lin of WHOI and Ross S. Stein of USGS write in a summary of their paper in press for publication in the Tohoku Earthquake Special Issue of the journal Earth, Planets and Space. 'A major shock does relieve stress—and thus the likelihood of a second major tremor—but only in some areas. The probability of a succeeding earthquake adjacent to the section of the fault that ruptured or on a nearby but different fault can jump' significantly.

The Tohoku earthquake, centered off northern Honshu Island, provided an 'unprecedented' opportunity to utilize Japan’s 'superb monitoring networks' to gather data on the quake, the scientists said. The Tohoku quake, the fourth largest earthquake ever recorded, was 'the best-recorded [large quake] the world has ever known.'

This made the quake a 'special' one in terms of scientific investigation, Lin said. 'We felt we might be able to find something we didn’t see before' in previous quakes, he said.

The magnitude 9 quake appears to have influenced large portions of Honshu Island, Toda said. At particular risk, he said, are the Tokyo area, Mount Fuji and central Honshu including Nagano.

The Kantu fragment, which is close to Tokyo, also experienced an increase in stress. Previous government estimates have put Tokyo at a 70 percent risk for a magnitude 7 earthquake over the next 30 years. The new data from the Tohoku quake increase those odds to 'more than 70 percent,' Toda said. 'That is really high.'

Using a model known as Coulomb stress triggering, Lin and his colleagues found measureable increases in stress along faults to the north at Sanriku-Hokobu, south at Off Boso and at the Outer Trench Slope normal faults east of the quake’s epicenter off the Japan coast near the city of Sendai.

'Based on our other studies, these stress increases are large enough to increase the likelihood of triggering significant aftershocks or subsequent mainshocks,' the researchers said.

Stein of the USGS emphasized the ongoing risk to parts of Japan. 'There remains a lot of real estate in Japan--on shore and off--that could host large, late aftershocks of the Tohoku quake,' he said.

'In addition to the megathrust surface to the north or south of the March 11 rupture, we calculate that several fault systems closer to Tokyo have been brought closer to failure, and some of these have lit up in small earthquakes since March 11. So, in our judgment, Central Japan, and Tokyo in particular, is headed for a long vigil that will not end anytime soon.'
Lin added that aftershocks, as well as new mainshocks, could continue for 'weeks, months, years.'

Toda explained that the magnitude of future quakes is proportional to the length of the fault involved.

In a separate paper submitted to Geophysical Research Letters, the researchers 'report on a broad and unprecedented increase in seismicity rate for microearthquakes over a broad (360 by 120 mile) area across inland Japan, parts of the Japan Sea and the Izu islands, following the 9.0 Tohoku mainshock.'

'The crust on the land was turned on…far away from a fault,' Lin said. Most of these are relatively small quakes—magnitude 2 to 4—'but a lot of them,' Lin said. 'This is surprising; we’ve never seen this before,' he said. 'Such small events…may have happened following major quakes in other places but may have been missed due to poor seismic networks.'

'The 9.0 Tohoku quake caught many people including scientists by surprise,' Lin said. 'It had been thought that a large quake in this area would go up to about 8.2, not 9.0' That estimate was significantly influenced by historical data. 'The Tohoku quake reminded us that considering only the historical earthquakes is inadequate, even in a country of relatively long written records like Japan and China,' he said.

'Historical records, and especially the instrumental records, are indeed too short to provide a full picture of the potential of large earthquakes in a region. Thus we must encourage many more studies to find geological evidence (for example, through analyzing sediment cores extracted on land and undersea) that might provide clues of large earthquake and tsunami events that occurred hundreds to thousands of years ago.'

'We must recognize that because our knowledge is incomplete, our estimation of seismic hazard is likely to be underestimated in many cases. Thus we must prepare for potential hazard that might be worse than we already know,' Lin said.

The finding that a quake such as this one can increase stresses elsewhere 'means that new quakes could occur in the region,' Lin said. 'We must factor in this new information on stresses into earthquake preparedness.'

Woods Hole Oceanographic Institution website




by Woods Hole Oceanographic Institution

  

Click on the FB Like link to post this story to your FB wall

http://www.powerboat-world.com/index.cfm?nid=84238

7:26 AM Thu 2 Jun 2011 GMT






Click here for printer friendly version
Click here to send us feedback or comments about this story.


Power Boat News



























Fort Lauderdale International Boat Show - 13 things to See and do by Fort Lauderdale International Boat Show,






























Yamaha inspires students to succeed by Yamaha Motor Australia,








Swan celebrates sales success *Feature by Jeni Bone,


4x4 Outdoors Show and Fishing and Boating Expo on the horizon
Polar research: Six priorities for Antarctic science
Stealth i14 out of China
Bivalves' ability to clean chemicals from waterways
Brisbane Boat Show 2014 - New boat engines set to rev up interest
Two rescued in tow from 13km offshore
Enhancing boating safety in the Mallacoota region
National 4x4 Outdoors Show and Fishing and Boating Expo - 4WD heaven
Yanmar selected for big torque at low revs
Sydney Boat Show display winners recognised *Feature
China Yachting Conference lines up the speakers
2014 National 4x4 Outdoors Show: Popularity of caravanning and camping
2015 Sydney Inte'l Boat Show - Boating Industry commences planning
Last chance to join 2014 Multihull Solutions Whitsunday Rendezvous
Dangerous conditions for boaters from this evening
Pacific Boating membership offers hassle-free boating *Feature
Marine15 expands trade, networking and B2B opportunities *Feature
2014 Auckland on the Water Boatshow - Huge prize packs up for grabs
4X4 Outdoors Show and Fishing and Boating Expo wows water lovers
John Wilson has sights set on second P1 SuperStock title
Torquay Grand Prix - Pertemps tops table on penultimate day   
Plain sailing for yachts with river cargo ship ban in Shanghai   
Dangerous conditions for boaters from this afternoon   
Sydney Int'l Boat Show - Stellar results for Multihull Solutions   
NSW Environment Minister awards 'Fish Friendly' Marina Accreditations   
Refurbished Protector project 'better than buying new'   
Gold Coast International Marine Expo - High-Diver Steve Black is back   
4x4 Outdoors Show, Fishing and Boating Expo - Campfire cooking corner   
See the heat with FLIR ONE *Feature   
John Temple to retire, Will Sangster appointed General Manager   
Multihull Central launches Aquila range at SIBS *Feature   
If all else fails read the instructions!!   
If all else fails read the instructions!!   
Sun shines on recreational boating at Sydney International Boat Show   
Phuket Yacht Show: new kid on the block taking on PIMEX? *Feature   
2014 Offshore Superboat Championships - The boats are back!   
Sydney International Boat Show - Days 3 & 4 *Feature   
Kirby Marine launch 13metre Naiad Tender   
Shellfish reefs in Port Phillip Bay to be rejuvenated   
2014 Brisbane Boat Show - What's your trailer boat worth?   


For this week's complete news stories select    Last 7 Days
   Search All News
For last month's complete news stories select    Last 30 Days
   Archive News







Sail-World.com  


















Switch Default Region to:

Social Media

Asia

Australia

Canada

Europe

New Zealand

United Kingdom


http://www.sail-world.com/event_images/image/Twitter_logo_small.png   http://www.sail-world.com/event_images/image/RSS-Icon.png

United States

Cruising Northern

Cruising Southern

MarineBusiness World

PowerBoat World

FishingBoating World

 

Contact

Commercial

News

Search

Contact Us

Advertisers Information

Submit news/events

Search Stories/Text

Feedback

Advertisers Directory

Newsletter Archive

Photo Gallery

 

Banner Advertising Details

Newsletter Subscribe

Video Gallery

Policies

 

 

 

Privacy Policy

 

 


Cookie Policy

 

 



This site and its contents are © Copyright TetraMedia and/or the original author, photographer etc. All Rights Reserved.  Photographs are copyright by law.  If you wish to use or buy a photograph contact the photographer directly.
XLXL WAS PBW
LocalAds   DE  ES  FR  IT