Iceland volcano eruption, earthquakes weaken, but scientists warn of lurking danger

A volcano that began erupting on Monday in Iceland continued to spew lava on Tuesday and was accompanied by hundreds of earthquakes across the magma flow on the country's southwestern coast, officials said.

The volcanic activity in Sundhnúksgígar on the Reykjanes peninsula appeared to be diminishing, according to Iceland's Meteorological Office. New aerial images analyzed Tuesday showed that there are now three vents belching lava southeast of Stóra-Skógfell, down from five at the start of the eruption in the Fagradalsfjall volcanic system, officials said.

"The lava flow is estimated to be about one-quarter of what it was at the beginning of the eruption," the Meteorological Office said in a statement Tuesday.

A third of the original fissure measuring 2 1/5 miles long remained active on Tuesday, officials.

"The lava fountains are also lower than at the start of the eruption, reaching about 30 meters [about 100 feet] at their highest," the Meteorological Office said.

At least 320 earthquakes, one measuring a magnitude 4.1, have occurred since the volcano blew Monday night, the Meteorological Office said Tuesday.

But since the eruption, seismic activity in the area has "significantly decreased," according to the Meteorological Office. Since noon on Tuesday, there had only been 10 earthquakes recorded in the region, officials said.

Following the volcanic eruption in Sundhnúksgígar, the land around the Svartsengi power station, a geothermal power plant, sank about 5 centimeters, or around 2 inches, officials said. Before the eruption, the land had risen by about 35 centimeters, or roughly 14 inches, due to the magma channel that had been building since November 10.

"It is too early to determine if magma will continue to accumulate under Svartsengi and whether the land will start to rise again," the Meteorological Office said.

The eruption north of the town of Grindavik started about 10 p.m. local time Monday, the Meteorological office announced in an alert on its website, noting, "It can be seen on webcams and seems to be located close to Hagafell, about 3 km [about 1.8 miles] north of Grindavík."

An "earthquake swarm" started about an hour before and eruption, the Meteorological Office said. The intensity of the eruption began to decrease within hours, officials said in an update about four hours later.

"The fact that the activity is decreasing already is not an indication of how long the eruption will last, but rather that the eruption is reaching a state of equilibrium," the Meteorological Office said.

The affected area near Grindavík, a fishing town of about 3,700 residents that was evacuated in November in preparation for the volcanic blast, remained closed off by the country's Civil Defense, President Guðni Th. Jóhannesson said on social media Tuesday.

"We now wait to see what the forces of nature have in store," he said. "We are prepared and remain vigilant."

While the eruption continues at Sundhnúksgíga, there is an increased likelihood that more vents may open along the original fissure as well as further north or south, officials said.

Looking back at the lead-up to the eruption revealed that there were approximately 90 minutes between the first indicators and the start of the eruption, the Meteorological Office said, adding that the warning time for new vent openings could be very short.

The Meteorological Office said the eruption was located on "the dyke intrusion that formed in November." The eruption fissure began expanding southward, with the southern end of it near Sundhnúkur, officials said.

Scientists estimated the lava discharge from the volcanic fissure to be "hundreds of cubic meters per second," adding that the biggest lava fountains were on the northern end. The lava was spreading laterally, the office said.

Local weather officials had warned in November there was a "significant likelihood" of a volcanic eruption. More than 20,000 quakes have shaken the area since late October, officials have said.

At the time, officials declared a state of emergency near the Mount Fagradalsfjall volcano on the sparsely populated Reykjanes Peninsula.