Featured Research

from universities, journals, and other organizations

Great-earthquake hot spots pinpointed

Date:
December 5, 2012
Source:
European Geosciences Union
Summary:
The world's largest earthquakes occur at subduction zones – locations where a tectonic plate slips under another. But where along these extended subduction areas are great earthquakes most likely to happen? Scientists have now found that regions where 'scars' on the seafloor, called fracture zones, meet subduction areas are at higher risk of generating powerful earthquakes.

Major earthquakes are associated with the intersection regions between oceanic fracture zones and subduction zones, where red and blue meet.
Credit: Müller and Landgrebe

The world's largest earthquakes occur at subduction zones -- locations where a tectonic plate slips under another. But where along these extended subduction areas are great earthquakes most likely to happen? Scientists have now found that regions where 'scars' on the seafloor, called fracture zones, meet subduction areas are at higher risk of generating powerful earthquakes.

The results are published December 5 in Solid Earth, an Open Access journal of the European Geosciences Union (EGU).

"We find that 87% of the 15 largest (8.6 magnitude or higher) and half of the 50 largest (8.4 magnitude or higher) earthquakes of the past century are associated with intersection regions between oceanic fracture zones and subduction zones," says Dietmar Müller, researcher at the University of Sydney in Australia and lead author of the Solid Earth paper. The connection is less striking for smaller earthquakes.

Powerful earthquakes related to these intersection regions include the destructive 2011 Tohoku-Oki and 2004 Sumatra events.

"If the association we found were due to a random data distribution, only about 25% of great subduction earthquakes should coincide with these special tectonic environments. Therefore, we can rule out that the link we found is just due to chance," he adds.

The researchers considered about 1,500 earthquakes in their study. They used a database of significant post-1900 events, as well as geophysical data mapping fracture zones and subduction zones, among others. They analysed information from these databases by using a specific data mining method.

"The method was originally developed for analysing online user data," says Thomas Landgrebe, also involved in the study. "The technique we apply is commonly used to find a few specific items which are expected to be most appealing to an Internet user. Instead, we use it to find which tectonic environment is most suitable for generating great earthquakes."

Since earthquake generation is a very complex process, the scientists don't yet have a complete understanding of why great earthquakes prefer the intersection areas. They suggest that it is due to the physical properties of fracture zones, which result in "strong, persistent coupling in the subduction boundaries," Landgrebe explains. This means that the subduction fault area is locked and thus capable of accumulating stress over long periods of time.

"The connection we have uncovered provides critical information for seismologists to, in the long run, pinpoint particular tectonic environments that are statistically more prone to strong seismic coupling and great earthquake supercycles," Müller says. An area with earthquake supercycles experiences recurring powerful earthquakes every few centuries or millennia.

Regions that have long earthquake supercycles are usually not picked up as risk areas by seismic hazard maps as these are constructed mainly using data collected after 1900. An example is the area of the 2011 Tohoku-Oki earthquake, which had no record of large earthquakes over the past century and was not predicted to be of significant risk by previous hazard maps.

"The power of our new method is that it does pick up many of these regions and, hence, could contribute to much-needed improvements of long-term seismic hazard maps," Müller explains.

"Even though we don't fully understand the physics of long earthquake cycles, any improvements that can be made using statistical data analysis should be considered as they can help reduce earthquake damage and loss of life."

Background

The floor of the Earth's oceans is crossed by underwater mountain systems, or ocean ridges, such as the mid-Atlantic ridge that runs from north to south between the Americas and Africa. These ridges divide two tectonic plates that move apart as lava emerges from the opening, spreading the sea floor. The mid-ocean ridge jogs back and forth at offsets known as transform faults, creating zig-zagged plate boundaries. Fracture zones are scars in the ocean floor left by these transform faults.


Story Source:

The above story is based on materials provided by European Geosciences Union. Note: Materials may be edited for content and length.


Journal Reference:

  1. R. D. Müller and T. C. W. Landgrebe. The link between great earthquakes and the subduction of oceanic fracture zones. Solid Earth, 2012 DOI: 10.5194/se-3-447-2012

Cite This Page:

European Geosciences Union. "Great-earthquake hot spots pinpointed." ScienceDaily. ScienceDaily, 5 December 2012. <www.sciencedaily.com/releases/2012/12/121205103003.htm>.
European Geosciences Union. (2012, December 5). Great-earthquake hot spots pinpointed. ScienceDaily. Retrieved April 20, 2014 from www.sciencedaily.com/releases/2012/12/121205103003.htm
European Geosciences Union. "Great-earthquake hot spots pinpointed." ScienceDaily. www.sciencedaily.com/releases/2012/12/121205103003.htm (accessed April 20, 2014).

Share This



More Earth & Climate News

Sunday, April 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Drought Concerns May Hurt Lake Tourism

Drought Concerns May Hurt Lake Tourism

AP (Apr. 18, 2014) — Operators of recreational businesses on western reservoirs worry that ongoing drought concerns will keep boaters and other visitors from flocking to the popular summer attractions. (April 18) Video provided by AP
Powered by NewsLook.com
Man Claims He Found Loch Ness Monster With... Apple Maps?

Man Claims He Found Loch Ness Monster With... Apple Maps?

Newsy (Apr. 18, 2014) — Andy Dixon showed the Daily Mail a screenshot of what he believes to be the mythical beast swimming just below the lake's surface. Video provided by Newsy
Powered by NewsLook.com
First Ever 'Female Penis' Discovered In Animal Kingdom

First Ever 'Female Penis' Discovered In Animal Kingdom

Newsy (Apr. 18, 2014) — Not only are these newly discovered bugs' sex organs reversed, but they also mate for up to 70 hours. Video provided by Newsy
Powered by NewsLook.com
Ark. Man Finds 6-Carat Diamond At State Park

Ark. Man Finds 6-Carat Diamond At State Park

Newsy (Apr. 18, 2014) — An Arkansas man has found a nearly 6.2-carat diamond, which he dubbed "The Limitless Diamond," at the Crater of Diamonds State Park. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins