Mapping a volcanic eruption in the backyard of the Icelandic capital

On March 19, 2021, the Fagradalsfjall volcano began to erupt, suggesting that volcanoes on Iceland’s Reykjanes Peninsula had awakened from an 800-year slumber. Although most volcanism in Iceland occurs in areas away from population centers, eruptions on the Reykjanes Peninsula can threaten residents.

“Basically, Fagradalsfjall is in the backyard of Iceland’s capital, Reykjavík. The peninsula is a young and rather pristine region of Iceland.

“Basically, Fagradalsfjall is in the backyard of Iceland’s capital, Reykjavík,” said University of Iceland researcher Gro BM Pedersen. “The peninsula is a young, rather pristine part of Iceland.”

Pedersen and a team of scientists came together to create maps to prepare the public for unfolding events. These mapping efforts were recently published in Geophysical Research Letters.

Map an eruption

According to Pedersen, it was difficult for researchers to predict what would happen when Fagradalsfjall erupted because they lacked a historical perspective for the area.

Scientists have started collecting data using satellite and aerial images. Although satellites provide ideal coverage of an area, clouds often obscure the satellite view of the sky above Iceland. For this reason, the team coupled satellite data with aerial photographs collected during 32 photogrammetric surveys. The researchers then used the data to construct topographic maps and monitor how the landscape changed between surveys. These maps illustrate the continuing evolution of the eruption.

Pedersen and his colleagues were surprised to see an eruption unlike most on the island. At the start of the event in March, lava began to fill the Geldingadalir Valley at a rate of 4 to 8 cubic meters per second. The event ended in mid-September, having produced a lava field that spanned 4.8 square kilometers with a bulk volume of 150×106 Cubic meters.

As the eruption progressed, several new fissures opened to the northeast, the rate of discharge increased, and lava began a process of “filling and pouring” into nearby valleys, endangering the communication cables, access to highways and sections of hiking trails.

“Just when we thought we figured out this eruption, another vent would open or another valley would flood,” Pedersen said. “We’ve seen many different styles of activity with the vent. From a volcanologist’s perspective, it was interesting.

Putting the cards to good use

Researchers were able to release meter-resolution maps to the public, disaster response agencies, and local police within 3 hours of data collection. Fagradalsfjall’s maps provided a window into the ever-changing hazards in the area, especially for the thousands of visitors who came to witness the eruption in person.

The experience illustrated how resources can be allocated to optimize mapping and modeling in different communities. For the researchers, Pedersen noted the need to build redundancy into their approach to data collection in order to maintain round-the-clock surveillance of the region.

For residents and visitors, the maps can “remind the public that the earth beneath them is actually very active and eruptions can still occur,” said Einat Lev, associate research professor at the Earth Observatory. Lamont-Doherty. Lev did not contribute to the study. “Once unrest begins, it is important to map out and pass on known or anticipated information about any potential activity. These should, of course, be updated as new information becomes available and the event develops.

—Stacy Kish (@StacyWKish), science writer

Quote: Kish, S. (2022), Mapping a volcanic eruption in the backyard of the Icelandic capital, Eos, 103, Posted July 19, 2022.
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