As
an island in the moist, atmospherically turbulent North Atlantic, Iceland is
often shrouded in cloud cover and hard to observe from space. And lately, the
island is making some of its own cloud cover, as the Earth has split open
between the Bardarbunga and Askja volcanoes and spewed lava and hot gas. The
view of the Holuhraun lava field has been spectacular from the ground and from
low-flying aircraft. Infrared imaging makes the view spectacular from space,
too.
On
September 6, 2014, the Operational Land Imager (OLI) on Landsat 8 captured this
view of the ongoing eruption. The false-color images combine shortwave
infrared, near infrared, and green light (OLI bands 6-5-3). Ice and the plume
of steam and sulfur dioxide appear cyan and bright blue, while liquid water is
navy blue. Bare or rocky ground around the Holuhraun lava field appears in
shades of green or brown in this band combination. Fresh lava is bright orange
and red. (Download this large image to see the same area in natural color.)
“Thermal imagery can be used to determine the extent of the lava flows
and the heat loss,” noted Ashley Davies, a Jet Propulsion Laboratory scientist
and leader of NASA’s Volcano Sensor Web team. Infrared imagery can help scientists
estimate the effusion rate—the rate at which lava is pouring out of the
Earth—as well as the sulfur dioxide content of the plume. “And high resolution
imagery of this kind allows us to model the dynamics of the emplacement
process. In this case, individual vents can be seen feeding separate lava flows
that combine into a main channel feeding an expanding lava flow field.”
By
some accounts, Holuhraun has spewed more lava this month that any Icelandic
volcano since the 19th century. As of September 9, 2014, the new lava flow was
16 kilometers (10 miles) long and covered about 20 square kilometers (8 square
miles), according to the University of Iceland.
The
plume from Holuhraun is rich with sulfur dioxide (SO2), a rotten-smelling gas
that can cause respiratory problems in humans and animals. A blue haze of SO2
and aerosols has been observed downwind over several towns and villages in
eastern Iceland. Scientists and other observers working near the eruption site
have been evacuated several times and cautioned to keep gas masks handy due to
noxious gases and shifting winds. Elevated levels of SO2 have been detected as
far as Ireland, Greenland, and Scandinavia.
The
University of Iceland and Iceland Met Office have been providing regular
updates on Holurhaun and Bardarbunga via Twitter and on their web site.
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