The Geldingadalir Eruption – A Timeline

On the evening of March 19th, an eruption began in Geldingadalir. Curiously enough, it was first noticed by people driving along Reykjanesbraut and not by the measuring equipment in the area. They noticed an odd red glow in the mountains. While it is assumed the eruption began around 9pm, it’s likely the eruption has already began before it was noticed.

It turned out to be a rather small eruption and initially it was thought that the eruption might be a short-lived one, lasting maybe a matter of days. Initially four vents formed but only two of them sustained throughout the night.

The second day, when it became clear how to approach the eruption, a handful of people hiked to the area. The hike was strenuous and long as there were no trails in the area. On the third day, about a thousand locals visited the eruption before a storm set in. It was a big and happy gathering, feeling a lot like an outdoor festival of some sorts.

The following days, the valley started filling with lava and a big lava lake formed around the vents. Additionally, the two vents grew out to become two big craters in just that first week.  Several thousand people hiked to the area to witness the spectacle and quickly proper hiking trails and improvised parking lots were created to deal with the traffic that came with it.

Into the second week of the eruption, the craters collapsed in on themselves and the vents seemed to be drowning in their own lava output. On April 4th, the lava output decreased a lot. This led several geologists to believe the eruption might have come to an end but exactly the opposite was true…

Around noon on April 5th, a new fissure opened up north of the active vent system. The area was quickly evacuated and closed off as no one knew what was going to happen next. Several hours later, another fissure opened parallel to the first one. The following day, another smaller fissure opened up in-between the original and the northernmost vent system. The area remained off-limits for everyone until it was determined that the changing behaviour had stabilised.

On April 7th, the area opened up for the first time after the new fissures opened up. Due to the bad weather conditions and gas accumulation, very few people went there on that day.

From this point on, the eruption would change very dramatically every few days. Several new vents opened up and the lava flow increased drastically in comparison to the first phase of the eruption.

On April 10th, a fourth vent system appeared just south of the northernmost crater. Just a few days later, on April 13th, two new vent systems appeared. Vent system number 5, which was closest to the original vents, started to quickly overtake everything, closing off the only passage to get close to those craters within days after appearing.

On the morning of April 15th, it was deemed too dangerous to allow people to walk closer to the craters due to risk that the only path in and out of the area would be closed off. Later that day, passage there was cut off by the flowing lava.

One by one, the newly formed vent systems started shutting down and activity started consolidating into vent system number 5.

Vent system number 5, the latest one to have formed in this eruption, becomes the only one to remain active. During the night of May 1st and May 2nd, the behaviour of the eruption changes. Where it was constantly erupting, it now changed into a pulsating pattern. Every 5-10 minutes, it would erupt to great heights after which it would recharge. At times, it could reach 450 metres in height. The lava fountain was often visible from Reykjavík.

Later into May, the lava fountain stopped reaching such incredible heights though the pulsating behaviour continued until the end of June. The crater kept growing in height. Towards the end of May, the inside of the crater became big enough to house a lava lake. The exit point, where the lava flowed out of the crater, turned into a big lava fall.

On May 31st, the closest viewing hill (Gónhóll) was closed off as it was feared the lava would overtake the path towards it. Just a few days later, the hill gets cut off by a lava flow. Shortly after that, the secondary viewing hill and hiking path A gets cut off by a lava flow exiting Geldingadalir. Most people start hiking up Langihryggur instead, creating path C in the process.

Authorities feared the road towards the southern end of the lava field would soon be destroyed by the new flow.

On June 28th, the eruption’s behaviour changed dramatically. The eruption went dormant for many hours and started up again the next day. On July 2nd, the eruption almost continuously erupted very large amounts of lava from the crater for hours as if it had been held back due to the break in activity.

From this point on, the eruption was active sporadically. Most of the time the period of inactivity lasted anywhere from 24 to 48 hours, followed by a period of 16-20 hours of activity. The only way to determine when the eruption would become active was to keep a close eye on the seismic data being gathered in the area. Many believed the eruption was either getting close to the end or that several blockages occurred in the newly formed magma intrusion, possibly caused by the weight of the lava on top.

The changes in activity also helped the lava find a new escape route, towards Meradalir in the east. This meant the lava field stopped expanding towards the south, sparing the road. When the lava flowed into Meradalir, a big lava fall would appear.

The erratic behaviour of the eruption continued on until September 1st.

Much to everyone’s surprise, the eruption began again after a 9-day hiatus. It seemed like something blocked the magma intrusion causing the lava to search for a new path to the surface. Once it did, the magma came up in the middle of the crater wall. This caused the wall to be split in two. Several secondary vents seemed to open in the lava field to the north east of the crater.

During the days that followed, the eruption did not slow down at all. Lava kept on flowing and a huge lava river formed in Geldingadalir. The lava output was so great, it looked like the lava was going to flow out of Geldingadalir into Nátthagakriki towards Svartsengi.

On September 18th, the visible activity seized and the eruption went dormant again.

New Earth: My Book About the Eruption

In December 2021, I self-published a book about the eruption in Geldingadalir “New Earth” became a uniquely personal, photography- and experience-focused book covering the recent volcanic eruption in Geldingadalir from the first until the last day it was active.