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NASA Satellite Photos Show How Lava has Grown

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NASA Satellite Photos Show How Lava has Grown

Holuhraun lava on January 3 2015

The satellite image shows the lava as is stood a week ago. Photo: NASA image courtesy of the Institute of Earth Sciences.

NASA has been following the Holuhraun eruption closely from the very beginning. The two images here show the eruption in the very early days and other the lava as it was in the beginning of January. An article accompanying the images reads:

“Since August 2014, lava has gushed from fissures just north of Vatnajökull, Iceland’s largest glacier. As of January 6, 2015, the Holuhraun lava field had spread across more than 84 square kilometers (32 square miles), making it larger than the island of Manhattan. Holuhraun is Iceland’s largest basaltic lava flow since the Laki eruption in 1783–84, an event that killed 20 percent of the island’s population.

The Operational Land Imager (OLI) on Landsat 8 captured this view of the lava field on January 3, 2015. The false-color images combine shortwave infrared, near infrared, and red light (OLI bands 6-5-4). The plume of steam and sulfur dioxide appears white. Newly-formed basaltic rock is black. Fresh lava is bright orange. A lava lake is visible on the western part of the lava field, and steam rises from the eastern margin where the lava meets the Jökulsá á Fjöllum river.

For comparison, the lower image shows the size of the lava field as observed by Landsat 8 on September 6, 2014. Beyond the growth of the lava field, notice that much of the flow was in lava rivers on the surface in September, while in January much of the lava was delivered to the eastern edge through a closed channel.

Scientists from the University of Iceland’s Institute of Earth Sciences have estimated the thickness of the lava field based on data from surveillance flights. On average, the eastern part was about 10 meters (33 feet) thick, the center was 12 meters, and the western part was 14 meters. Their preliminary analysis put the volume of lava at 1.1 cubic kilometers, enough for the eruption to be considered a flood basalt.

The Holuhraun eruption in early September 2014.

The Holuhraun eruption in the very beginning, September 2014. Photo: NASA.

While Holuhraun continues to spew copious amounts of lava and sulfur dioxide, some observations suggest the eruption may be slowing down. As Edinburgh University volcanologist John Stevenson noted on his blog, Icelandic scientists have shown that the sinking (subsidence) of the caldera has declined from 80 centimeters (31 inches) to 25 centimeters per day—a sign that less magma is moving toward the surface. In addition, magnitude 5 or higher earthquakes that used to occur daily are now happening about once a week. Meanwhile, satellite observations of heat flux show a decline from more than 20 gigawatts in early September to fewer than 5 gigawatts by the end of November.

Map of Holuhraun lava on January 3 2015

The map shows the lava and some well known tourist destinations.

“This doesn’t mean that the eruption will stop soon. Like the weakening spray from an aerosol can, the eruption rate declines exponentially. The lower the flow, the more slowly it declines,” said Stevenson. Some volcanologists have predicted lava could continue to flow for years.”

The original article can be read here.

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