Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists detect seasonal pattern to glacial earthquakes in Greenland, see signs of increase

24.03.2006


Rise of seismic activity linked to the movement of glaciers may be a response to global warming

Seismologists at Columbia University and Harvard University have found a new indicator that the Earth is warming: "glacial earthquakes" caused when the rivers of ice lurch unexpectedly and produce temblors as strong as 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.

Seismologists Göran Ekström and Victor C. Tsai at Harvard and Meredith Nettles at the Lamont-Doherty Earth Observatory, a member of The Earth Institute at Columbia University, will publish a 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 increasing 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 at Harvard who will be moving to Lamont-Doherty in the spring. "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 10 cubic kilometers in size to lurch down valleys known as "outlet glaciers," which funnel all of Greenland’s glacial runoff toward the surrounding seas.

"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 Lamont-Doherty. "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."

Although Greenland is not known as a hotbed of traditional seismic activity caused by 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 were found to have originated at major valleys draining the Greenland Ice Sheet, implicating glacial activity in the seismic disturbances.

Moreover, of the earthquakes they analyzed, the researchers found more than one-third occurred during the months of July (22 earthquakes) and August (24). By comparison, January and February each saw a total of only such four glacial earthquakes between 1993 and 2005. In contrast, non-glacial earthquakes in northern latitudes show no such seasonal variability.

In addition, the number of glacial earthquakes in Greenland increased markedly between 1993 and 2005. Annual totals hovered between 6 and 15 through 2002, which was followed by sharp increases to 20 earthquakes in 2003, 24 in 2004 and 32 in the first ten months of 2005. A single area of northwestern Greenland, where only one seismic event was observed between 1993 and 1999, experienced more than two dozen glacial quakes between 2000 and 2005.

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

Ken Kostel | EurekAlert!
Further information:
http://www.earth.columbia.edu

More articles from Earth Sciences:

nachricht In times of climate change: What a lake’s colour can tell about its condition
21.09.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

nachricht Did marine sponges trigger the ‘Cambrian explosion’ through ‘ecosystem engineering’?
21.09.2017 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>