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 NASA eyes Pineapple Express soaking California
24.02.2017 | NASA/Goddard Space Flight Center

nachricht 'Quartz' crystals at the Earth's core power its magnetic field
23.02.2017 | Tokyo Institute of Technology

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>