Andrew Yee
March 9th 06, 03:35 PM
ESA News
http://www.esa.int
9 March 2006
ESA satellite reveals Yellowstone's deep secret
Satellite images acquired by ESA's ERS-2 revealed the recently discovered
changes in Yellowstone's caldera are the result of molten rock movement 15
kilometres below the Earth's surface, according to a recent study
published in Nature.
Using Synthetic Aperture Radar Interferometry, InSAR for short, Charles
Wicks, Wayne Thatcher and other U.S. Geological Survey (USGS) scientists
mapped the changes in the northern rim of the caldera, or crater, and
discovered it had risen about 13 centimetres from 1997 to 2003.
InSAR, a sophisticated version of 'spot the difference', involves
mathematically combining different radar images, acquired from as near as
possible to the same point in space at different times, to create digital
elevation models and reveal otherwise undetectable changes occurring
between image acquisitions.
"We know now how mobile and restless the Yellowstone caldera actually is.
Ground-based measurements can be more efficiently deployed because of our
work," Thatcher said. "The research could not have been done without
satellite radar data."
About 640,000 years ago, a massive volcano erupted in Yellowstone,
creating the caldera, which measures some 45 kilometres wide and 75
kilometres long, in the centre of Yellowstone National Park.
At the same time the northern rim of the caldera began rising -- referred
to as the North Rim Uplift Anomaly (NUA) -- in 1997, the floor of the
caldera began sinking.
According to the article, published on 2 March 2006, the floor sank as the
molten rock (magma) flowed out of the caldera into the Yellowstone
volcanic system.
The uplift of the caldera's rim is theorised to have occurred even as the
floor sank because one of the natural valves, which allow the magma to
enter into the volcanic system, was unable to accommodate the increased
flow of magma, causing it to accumulate beneath the north caldera
boundary.
The magma movement may have also triggered the sudden rise in temperatures
at the Norris Geyser Basin and the eruption of the Steamboat Geyser in
2000. The world's largest geyser, Steamboat had been inactive for nine
years, but erupted five times between 2000 and 2003.
The disturbances in the geyser during that three-year period are not
unique in Yellowstone's history, but, as stated in the article, this is
the first time the changes in the deformation field in the park suggests a
cause-and-effect relationship -- thanks to the use of InSAR data.
Despite the activity in the caldera, Thatcher said the likelihood for a
magmatic eruption is extremely low. However, the area poses other
potential risks.
"The possibility of a steam-water explosion ('Phreatic eruption') is
perhaps the greatest risk. Its effects would be quite local, but still
potentially dangerous," he said.
Having access to data over long periods of time is important for
scientists to identify and analyse long-term trends and changes. ESA now
has a 15-year archive of homogenous data thanks to the continuity of
satellites ERS-1, ERS-2 and Envisat. Envisat and ERS-2, with a difference
in overpass time of 30 minutes, are continually adding to the archive.
"The complete aerial coverage and frequent repeat satellite passes creates
a unique suite of deformation measurements of restless volcanoes
worldwide. They are particularly useful in remote and inaccessible areas.
We will continue to monitor Yellowstone with InSAR imaging," Thatcher
said.
Related news
* Double views from ERS tandem mission adding depth to Canadian wilderness
maps
http://www.esa.int/esaCP/SEMDKSLVGJE_index_0.html
* A decade after launch, ERS-2's mission continues
http://www.esa.int/esaCP/SEM3MZW797E_index_0.html
Related Missions
* ERS overview
http://www.esa.int/esaEO/SEMGWH2VQUD_index_0_m.html
Related links
* Nature article: Uplift, thermal unrest and magma intrusion at
Yellowstone caldera
http://www.nature.com/nature/journal/v440/n7080/full/nature04507.html
* USGS
http://www.usgs.gov/
IMAGE CAPTIONS:
[image 1:
http://www.esa.int/esaCP/SEM9YBNVGJE_index_1.html]
The rim of the Yellowstone Caldera.
Credits: http://www.yellowstonegis.utah.edu/home/home.html
[Image 2:
http://www.esa.int/esaCP/SEM9YBNVGJE_index_1.html#subhead1]
This image of ground deformation was created using data from several
satellite passes from 1996 through 2000. The image shows 125 mm of uplift
centred within the northern end of Yellowstone caldera (black dotted
line), about 10 km south of Norris. Each full spectrum of colour (from red
to purple) represents about 28 mm of uplift. The uplift is approximately
35 km x 40 km in size.
Credits: U.S. Geological Survey
[Image 3:
http://www.esa.int/esaCP/SEM9YBNVGJE_index_1.html#subhead2]
Using InSAR to look at ground deformation
A satellite passes over an area and records data about it. Two or more
passes are needed to create the InSAR (Synthetic Aperture Radar
Interferometry) images, used to examine changes in ground height.
Credits: U.S. Geological Survey
http://www.esa.int
9 March 2006
ESA satellite reveals Yellowstone's deep secret
Satellite images acquired by ESA's ERS-2 revealed the recently discovered
changes in Yellowstone's caldera are the result of molten rock movement 15
kilometres below the Earth's surface, according to a recent study
published in Nature.
Using Synthetic Aperture Radar Interferometry, InSAR for short, Charles
Wicks, Wayne Thatcher and other U.S. Geological Survey (USGS) scientists
mapped the changes in the northern rim of the caldera, or crater, and
discovered it had risen about 13 centimetres from 1997 to 2003.
InSAR, a sophisticated version of 'spot the difference', involves
mathematically combining different radar images, acquired from as near as
possible to the same point in space at different times, to create digital
elevation models and reveal otherwise undetectable changes occurring
between image acquisitions.
"We know now how mobile and restless the Yellowstone caldera actually is.
Ground-based measurements can be more efficiently deployed because of our
work," Thatcher said. "The research could not have been done without
satellite radar data."
About 640,000 years ago, a massive volcano erupted in Yellowstone,
creating the caldera, which measures some 45 kilometres wide and 75
kilometres long, in the centre of Yellowstone National Park.
At the same time the northern rim of the caldera began rising -- referred
to as the North Rim Uplift Anomaly (NUA) -- in 1997, the floor of the
caldera began sinking.
According to the article, published on 2 March 2006, the floor sank as the
molten rock (magma) flowed out of the caldera into the Yellowstone
volcanic system.
The uplift of the caldera's rim is theorised to have occurred even as the
floor sank because one of the natural valves, which allow the magma to
enter into the volcanic system, was unable to accommodate the increased
flow of magma, causing it to accumulate beneath the north caldera
boundary.
The magma movement may have also triggered the sudden rise in temperatures
at the Norris Geyser Basin and the eruption of the Steamboat Geyser in
2000. The world's largest geyser, Steamboat had been inactive for nine
years, but erupted five times between 2000 and 2003.
The disturbances in the geyser during that three-year period are not
unique in Yellowstone's history, but, as stated in the article, this is
the first time the changes in the deformation field in the park suggests a
cause-and-effect relationship -- thanks to the use of InSAR data.
Despite the activity in the caldera, Thatcher said the likelihood for a
magmatic eruption is extremely low. However, the area poses other
potential risks.
"The possibility of a steam-water explosion ('Phreatic eruption') is
perhaps the greatest risk. Its effects would be quite local, but still
potentially dangerous," he said.
Having access to data over long periods of time is important for
scientists to identify and analyse long-term trends and changes. ESA now
has a 15-year archive of homogenous data thanks to the continuity of
satellites ERS-1, ERS-2 and Envisat. Envisat and ERS-2, with a difference
in overpass time of 30 minutes, are continually adding to the archive.
"The complete aerial coverage and frequent repeat satellite passes creates
a unique suite of deformation measurements of restless volcanoes
worldwide. They are particularly useful in remote and inaccessible areas.
We will continue to monitor Yellowstone with InSAR imaging," Thatcher
said.
Related news
* Double views from ERS tandem mission adding depth to Canadian wilderness
maps
http://www.esa.int/esaCP/SEMDKSLVGJE_index_0.html
* A decade after launch, ERS-2's mission continues
http://www.esa.int/esaCP/SEM3MZW797E_index_0.html
Related Missions
* ERS overview
http://www.esa.int/esaEO/SEMGWH2VQUD_index_0_m.html
Related links
* Nature article: Uplift, thermal unrest and magma intrusion at
Yellowstone caldera
http://www.nature.com/nature/journal/v440/n7080/full/nature04507.html
* USGS
http://www.usgs.gov/
IMAGE CAPTIONS:
[image 1:
http://www.esa.int/esaCP/SEM9YBNVGJE_index_1.html]
The rim of the Yellowstone Caldera.
Credits: http://www.yellowstonegis.utah.edu/home/home.html
[Image 2:
http://www.esa.int/esaCP/SEM9YBNVGJE_index_1.html#subhead1]
This image of ground deformation was created using data from several
satellite passes from 1996 through 2000. The image shows 125 mm of uplift
centred within the northern end of Yellowstone caldera (black dotted
line), about 10 km south of Norris. Each full spectrum of colour (from red
to purple) represents about 28 mm of uplift. The uplift is approximately
35 km x 40 km in size.
Credits: U.S. Geological Survey
[Image 3:
http://www.esa.int/esaCP/SEM9YBNVGJE_index_1.html#subhead2]
Using InSAR to look at ground deformation
A satellite passes over an area and records data about it. Two or more
passes are needed to create the InSAR (Synthetic Aperture Radar
Interferometry) images, used to examine changes in ground height.
Credits: U.S. Geological Survey