Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Global warming yields novel ’glacial earthquakes’ in polar areas

24.03.2006


Newfound temblors, most common in summer months, have proliferated in recent years



Seismologists at Harvard University and Columbia University have found an unexpected offshoot of global warming: "glacial earthquakes" in which Manhattan-sized glaciers lurch unexpectedly, yielding temblors up to magnitude 5.1 on the moment-magnitude scale, which is similar to the Richter scale. Glacial earthquakes in Greenland, the researchers found, are most common in July and August, and have more than doubled in number since 2002.

Scientists Göran Ekström and Victor C. Tsai at Harvard and Meredith Nettles at Columbia will report on Greenland’s glacial earthquakes this week in the journal Science. Ekström, Nettles and colleagues first described glacial earthquakes in 2003, but that report did not recognize the seasonality or growing frequency of the phenomenon.


"People often think of glaciers as inert and slow-moving, but in fact they can also move rather quickly," says Ekström, professor of geology and geophysics in Harvard’s Faculty of Arts and Sciences. "Some of Greenland’s glaciers, as large as Manhattan and as tall as the Empire State Building, can move 10 meters in less than a minute, a jolt that is sufficient to generate moderate seismic waves."

As glaciers and the snow atop them gradually melt, water seeps downward. When enough water accumulates at a glacier’s base, it can serve as a lubricant, causing blocks of ice some 10 cubic kilometers in size to lurch down valleys known as "outlet glaciers," which funnel all of Greenland’s glacial runoff toward the surrounding sea.

"Our results suggest that these major outlet glaciers can respond to changes in climate conditions much more quickly than we had thought," says Nettles, a postdoctoral researcher at Columbia’s Lamont-Doherty Earth Observatory. "Greenland’s glaciers deliver large quantities of fresh water to the oceans, so the implications for climate change are serious. We believe that further warming of the climate is likely to accelerate the behavior we’ve documented."

While Greenland is not a hotbed of traditional seismic activity associated with the grinding of the Earth’s tectonic plates, seismometers worldwide detected 182 earthquakes there between January 1993 and October 2005. Ekström, Nettles and Tsai examined the 136 best-documented of these seismic events, ranging in magnitude from 4.6 to 5.1. All 136 temblors were found to have originated at major valleys draining the Greenland Ice Sheet, implicating glacial activity in the seismic disturbances.

Of the 136 earthquakes analyzed, more than a third occurred during the months of July (22 earthquakes) and August (24 earthquakes). By comparison, January and February each saw a total of only four earthquakes between 1993 and 2005. Non-glacial earthquakes in polar regions show no seasonal variability.

Greenland’s overall number of glacial earthquakes also increased markedly between 1993 and 2005. Annual totals hovered between 6 and 15 through 2002, followed by sharp increases to 20 earthquakes in 2003, 24 in 2004, and 32 in the first 10 months of 2005. A single area of northwestern Greenland, where only one seismic episode was observed between 1993 and 1999, experienced more than two dozen glacial quakes between 2000 and 2005. Polar regions have not experienced increases in non-glacial earthquakes in recent years.

While glacial earthquakes appear most common in Greenland, Ekström, Nettles and Tsai have also found evidence of glacial earthquakes originating at mountain glaciers in Alaska and at glaciers located in ice streams among the edges of Antarctica.

Steve Bradt | EurekAlert!
Further information:
http://www.harvard.edu

More articles from Earth Sciences:

nachricht Live from the ocean research vessel Atlantis
13.12.2018 | National Science Foundation

nachricht NSF-supported scientists present new research results on Earth's critical zone
13.12.2018 | National Science Foundation

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Data use draining your battery? Tiny device to speed up memory while also saving power

The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.

Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...

Im Focus: An energy-efficient way to stay warm: Sew high-tech heating patches to your clothes

Personal patches could reduce energy waste in buildings, Rutgers-led study says

What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...

Im Focus: Lethal combination: Drug cocktail turns off the juice to cancer cells

A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.

The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...

Im Focus: New Foldable Drone Flies through Narrow Holes in Rescue Missions

A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.

Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...

Im Focus: Topological material switched off and on for the first time

Key advance for future topological transistors

Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

 
Latest News

Data use draining your battery? Tiny device to speed up memory while also saving power

14.12.2018 | Power and Electrical Engineering

Tangled magnetic fields power cosmic particle accelerators

14.12.2018 | Physics and Astronomy

In search of missing worlds, Hubble finds a fast evaporating exoplanet

14.12.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>