Monday, 14 March 2011

Climate Change IS Increasing the Frequencies of Major Geological Events

Climate Change IS Increasing the Frequencies of Major Geological Events

Spinning Globe

There will be more earthquakes, volcanic eruptions and landslides both on the land and sea floor

 NASA and United States Geological Survey (USGS) scientists have found that retreating glaciers in southern Alaska may lead to more earthquakes in future (see study below).

"Climate change: Tearing the Earth apart?"

Bill McGuire, professor of Geophysical Hazards at University College, in an article in New Scientist, titled "Climate change: Tearing the Earth apart?" wrote:

"In the early 1970s John Chappell of the Australian National University in Canberra was the first to make the link between glacial advances and retreats and the rate of global volcanism. We now know that the warming that heralded the start of the current interglacial period around 10,000 years ago brought forth a burst of volcanic activity in Iceland, as melting ice caps reduced pressures on the magma chambers below. Allen Glazner of the University of North Carolina at Chapel Hill identified a similar pattern in eastern California over the past 800,000 years. Increased levels of volcanic activity are also recorded at mid-latitude ice-covered volcanoes in the Cascades Range of the US and in the Andes."

"[I]t shouldn’t come as a surprise that the loading and unloading of the Earth’s crust by ice or water can trigger seismic and volcanic activity and even landslides. Dumping the weight of a kilometre-thick ice sheet onto a continent or removing a deep column of water from the ocean floor will inevitably affect the stresses and strains on the underlying rock.” McGuire said.

“Not every volcanic eruption and earthquake in the years to come will have a climate-change link…  Yet as the century progresses we should not be surprised by more geological disasters as a direct and indirect result of dramatic changes to our environment. The only saving grace is that a significant increase in volcanic activity would pump large volumes of sulphate gases into the stratosphere, which would cool the Earth’s surface and slow global warming, at least for a time. It’s a hell of a price to pay, though, for ignoring a phenomenon that could be far more easily sorted if we lived more considered and sustainable lives.” He said.

FEWW Team believes that aerial bombardment, nuclear tests, large scale urbanization, use of explosives for mining and similar activities, as well as human mobility also play  significant roles in increasing the frequencies of earthquakes, volcanic eruptions and land and sea-floor landslides.



 RETREATING GLACIERS SPUR ALASKAN EARTHQUAKES

 NASA and United States Geological Survey (USGS) scientists have found that retreating glaciers in southern Alaska may be opening the way for future earthquakes.



Rollover for the difference in the Bering Glacier from October 1986 to September 2002
Item 1
Click on image to view animation.

The study examined the likelihood of increased earthquake
activity in southern Alaska as a result of rapidly melting
glaciers. As glaciers melt they lighten the load on the
Earth's crust. Tectonic plates, that are mobile pieces of the
Earth's crust, can then move more freely. The study appeared
in the Journal of Global and Planetary
Change.

Jeanne Sauber of NASA's Goddard Space Flight Center,
Greenbelt, Md., and Bruce Molnia, a research geologist at
USGS, Reston, Va.,


3 Tier Comparison of the number of earth quakes.
Item 2
In this image series the size of the ring around each earthquake represents its relative magnitude. Click image to view animation.
used NASA satellite and global positioning
system receivers, as well as computer models, to study
movements of Earth's plates and shrinking glaciers in the
area.

"Historically, when big ice masses started to retreat, the
number of earthquakes increased," Sauber said. "More than
10,000 years ago, at the end of the great ice age, big
earthquakes occurred in Scandinavia as the large glaciers
began to melt. In Canada, many more moderate earthquakes
occurred as ice sheets melted there," she added.

Southern Alaskan glaciers are very sensitive to climate
change, Sauber added. Many glaciers have shrunk or
disappeared over the last 100 years. The trend, which appears
to be accelerating, seems to be caused by higher temperatures
and changes in precipitation.

In southern Alaska,



 Item 3
Click on image to view animation.
a tectonic plate under the Pacific Ocean
is pushing into the coast, which creates very steep
mountains. The high mountains and heavy precipitation are
critical for glacier formation. The colliding plates create a
great deal of pressure that builds up, and eventually is
relieved by earthquakes.

The weight of a large glacier on top of these active
earthquake areas can help keep things stable. But, as the
glaciers melt and their


Item 4
Click on image to view animation.
load on the plate lessens, there is a
greater likelihood of an earthquake happening to relieve the
large strain underneath.

Even though shrinking glaciers make it easier for earthquakes
to occur, the forcing together of tectonic plates is the main
reason behind major earthquakes.

The researchers believe that a 1979 earthquake in southern
Alaska, called the St. Elias earthquake, was promoted by
wasting glaciers in the


Item 5
Click for animation of a flying tour through Glacier Bay National Park and Preserve in southern Alaska featuring Landsat imagery draped over elevation data.
area. The earthquake had a magnitude
of 7.2 on the Richter scale.

Along the fault zone, in the region of the St. Elias
earthquake, pressure from the Pacific plate sliding under the
continental plate had built up since 1899 when previous
earthquakes occurred. Between 1899 and 1979, many glaciers
near the fault zone thinned by hundreds of meters and some
completely disappeared. Photographs of these glaciers, many
taken by Molnia during the last 30 years, were used to
identify details within areas of greatest ice loss.

Field measurements were also used to determine how much the
glacier's ice thickness changed since the late 19th century.
The researchers estimated the volume of ice that melted and
then calculated how much


Item 6
Click for animation showing a cumulative view of earthquake activity for the whole world from 1960 through 1995.
instability the loss of ice may have
caused. They found the loss of ice would have been enough to
stimulate the 1979 earthquake.

Along with global positioning system measurements made by
Sauber and Molnia a number of NASA satellites were used to
document glacier variability. Data from Landsat-7 and the
Shuttle Radar Topography Mission (SRTM) were used to study
glacier extent and topography. Currently, NASA's ICESat
satellite is being used to measure how the glacier
thicknesses are changing.

"In the future, in areas like Alaska where earthquakes occur
and glaciers are changing, their relationship must be
considered to better assess earthquake hazard, and our
satellite assets are allowing us to do this by tracking the
changes in extent and volume of the ice, and movement of the
Earth," Sauber said.



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