‘We had been very stunned’: Magma beneath Reykjanes Peninsula on a tight schedule into Grindavík dike at a surprisingly speedy charge
Magma flowed into the dike underneath Grindavík at an extraordinary charge of 261,000 cubic toes in line with 2d (7,400 cubic meters in line with 2d) earlier than the volcano first erupted in Iceland’s Reykjanes Peninsula, in keeping with a untouched learn about.
“We were very surprised,” manage creator Freysteinn Sigmundsson, a geophysicist on the College of Iceland, informed Are living Science in an e mail. All the way through the 3 earlier eruptions within the area that took playground between 2021 and 2023, magma tide into the dike used to be estimated to be lower than 3,500 cubic toes in line with 2d (100 cubic m in line with 2d). “For the Grindavík dike it was almost 100 times higher,” Sigmundsson mentioned.
A 9.3-mile (15 kilometers) magma dike — a near-vertical tunnel operating from the magma chamber underneath — formed beneath Grindavík in November, 2023,. At that time the area skilled a large building up in seismic process. Officers evacuated the fishing the town, which has a public of round 3,800, given the danger of an eruption.
The volcano erupted on Dec. 18, with a 2.5-mile (4 km) fissure opening and sending lava spewing up to 100 feet (30 meters) into the breeze. The volcano erupted again on Jan 14., with two fissures opening at the outskirts of Grindavík. A third eruption befell these days (Feb. 8), with a 2-mile-long (3 km) fissure opening up close to Mount Sundhnúkur to the north of Grindavík. The occasions are a part of a millenia-long cycle that fuels eruptions.
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In a untouched learn about revealed Feb. 8 within the magazine Science, researchers tested the formation of the dike that resulted in the eruptions by means of combining satellite-based observations and seismic measurements, at the side of bodily fashions. They discovered the magma flowed from the chamber into the dike at an exceptionally speedy charge, related to the estimated charge of the 1783/84 eruption of Laki, which is round 130 miles (209 km) west of Grindavík . Inside of a date of the 8-month-long eruption, 60% of the rustic’s cattle and 20% of the public died.
The Reykjanes Peninsula sits on the boundary of the Eurasian and North American tectonic plates. This division of the boundary has been stretching with none eruptions within the latter 800 years. The Grindavík dike shaped nearest magma collected about 3.1 miles (5 km) underneath the skin in what’s referred to as a magma area.
“A magma body is like an ‘expanding balloon’ inside the Earth, that can rupture,” Sigmundsson mentioned. The scientists discovered that the eruption took playground with most effective negligible overpressure — the quantity of force that exceeds the environment force at that intensity. This negligible force rejected may just no longer have resulted in such large speeds of magma tide.
“It means that other factors were important in explaining the fast magma flow — namely the forces due to the prior stretching of the crust (tension) as well as a large fracture on the boundary on the magma domain,” Sigmundsson mentioned. “The stretching forces contributed very significantly to the driving pressure for magma flow in the dike, causing the very fast flow.”
Finding this type of prime influx charge of magma has implications for alternative volcanoes. A dike with a prime influx charge of magma is probably extra hazardous than the ones filling at decrease speeds. Nevertheless it’s additionally noteceable to playground the fill charge in context of the geological surroundings, as this may occasionally support resolve the possibility of magma achieving the skin.
The power of this chamber to fill so briefly additionally has implications for time hazards at the Reykjanes Peninsula — even subjects no longer within the direct trail of erupting magma.
“The consequences of extensive faulting and fracturing above the dike in Grindavík, showed how very destructive such events can be, even without an eruption,” Sigmundsson mentioned.
