Summer fieldwork in Iceland
Text and photos by Erik Sturkell
On the last day in July, I traveled to Iceland for carrying out fieldwork around the Askja volcano. This volcano has inflated since August 2021 with nearly 70 cm until late summer 2023. The continues GPS stations indicate that uplift is still taking place but at a slower rate, whereas a brand new InSAR image shows uplift.
On the 6th of August, which is the day of national holiday “Verslunarmannahelgi” we set out from Reykjavík in three cars. There was one car with Michelle, and Asta Rut from Vedurstofan (IMO), plus Ana a post-doc in Italy, and Sveinbjörn, Sonja and Cat (Catherine) from the University of Iceland, and I in the new Ford and in my Landcruiser. The Vedurstofan car went to Nýidalur on the Sprengisandi road to install GPE instruments near Bárðarbunga, which shows some seismic activity. They were to join up in Askja on the evening the 7th. The four of us in the other two cars drove to the house in Reykjahlid (Mývatn) and continued to Askja the next day. In addition to our two groups Freysteinn, Elske, Fjóla, and Greta were to come on late in the evening on the 9thto do micro gravity measurements. Our group were set to do GPS and levelling (the long line and some tilt stations) and we had to be ahead of the gravity measurements. Almost all gravity sites are on a GPS benchmark so the measurements must be done before. On the 7th we set out four GPS instruments in the caldera which is also gravity sits plus two additional instruments. The GPS instruments must collect data for two complete sessions so they can be collected after four days. In this case that was on the 10th, the same day as the gravity measurement started. The gravity measurements are made through a loop: the base station (at the hut Dyngja), a few sites and to close the loop back to the base station. Only selected gravity sites can be measured every day, fewer in bad weather. In the evening of the 7th, Michelle, Ásta, and Ana arrived, and in the evening, we had chicken breast with bacon and baby spinach for dinner. During the dinner the oven in the house started to burn out of control as some of the fuel had assembled at its base. The incoming fuel supply was turned off and the remaining fuel in the base of the oven burned out after some minutes, but the house was densely smoked. We found other accommodations for our group. On the 8th we (Michelle, Ásta, Ana and I) started with the levelling. It worked very well, and we started at 9 AM and decided to retire at 5 PM. At the end of the day, we had reached benchmark 423. The leveling line consist of 35 benchmarks but there are five extra points between the numbered benchmarks. The two first benchmarks were buried under the snow. This is not uncommon and happens every third year. We finished 26 benchmarks measuring in both directions. Sveinbjörn, Sonja and Cas deployed GPS instruments both inside and outside of the caldera on the south side of Askja. Most of these sites are GPS sites and they will be free on Sunday the 11th.
The next day the 9th the weather was perfect, and we (Sveinbjörn, Sonja, Cas, and I) finished the long leveling line in two hours. At the same time Michelle, Ásta, and Ana went to do gas and water measurements in the Viti crater. They were joined by a journalist and two photographers from Reuters, who all went down the slippery slope to Viti. The pH in the Viti water is about 2.4 (Coca Cola has pH 2.6) so you should not soke in the water too long. After we were done with the long line, we continued to the lake shore next to the Viti crater. At this location we have a benchmark at which we measure the lake level. After this was done, we went to the new tilt station located on Batshraun, where also the GPS site is located. We started with the leveling of the tilt station and the people from Reuters came and started to interview me. Sveinbjörn, Sonja and Cas continued to do the leveling, they performed well while I enjoyed the media. After the leveling was completed and the journalist gone, we returned to the cars. I did all the calculations of the result and could say from the leveling that Askja is still rising but a little bit slower than previous years. Michelle had planned an information meeting for the rangers and the police, and we could give the brand-new results from the leveling and the measurements in Viti. Later that evening the gravity team arrived: Freysteinn, Elske, Fjóla and Greta, they started directly with the next morning the 10th. On this day (Saturday) all except the gravity team went in to get three GPS instruments in the caldera. Sveinbjörn went to the CASK GPS site which is an antenna on a rod. He took it down and moved it to the Batshraun site, the one site we had left a tripod and a battery. The rest of us went for two GPS instruments of which one should be moved to the leveling line, so we brought a fresh battery on the way. We had a nice hike to retrieve the instrument and clear the sites for the gravity survey. In the afternoon Sonja, Ásta (who was free as Michelle talked to Reuters) and I did the tilt station at Nautahnútur which just showed minor changes.
On Sunday Sonja and I went north of Askja on Vikrafellsleið and we gave Simon (a Swiss PhD student) a ride to Reykjahlið as it was our final destination that day. We had four GPS instruments to deploy and three tilt stations to measure. We left Dreki at 9 AM and finished the last site at 3:15P M. Which was in the southern end of Dyngjufjalladalur and we had two options to go to Reykahlið: one longer and one more terrible; around Askja on the southern side to Dreki and to Rekjahlið (4½ – 5 hour) or directly north passing Sudurábotnar in just less than 3 hours. This time I chose short but difficult through pahoehoe lava flows for about an hour of the travel time. This is a truly terrible part traveling in only a few km per hour. When you believe you have passed the worst part one more stretch appears, but it is short. We had to do some shopping in Rekjahlid for the dinner (barbeque) and we got in contact with the net. On the home page of the shop in Rekjahlið it was proclaimed it closes at 6 PM, so now it was a race. We arrived in Rekjahlið at 5:50PM to realize the home page was not updated for the summer open hours which is closing at 9 PM.
We came down on Sunday the 11th with all GPS instruments out working on the final sites for this campaign. With all the levelling done it was just to pick the instruments up starting on Tuesday, so we had a relaxing day at Helluhraun 1 in Rekjahlið. I went down to Húsavík to shop for the barbeque for all the group and the Ranges on Tuesday night I Dreki. Unfortunate I missed our whale researcher friend Marianne who works in Húsavík.
On Tuesday morning we traveled into Askja and started in the caldera retrieving GPS instruments. Our group picked up the two last instruments in the caldera, so it was no obstructs for the gravity measurements. In the evening, we hosted a barbeque for thirteen persons in the tourist hut. In the group it was two vegetarians, but they made their own food. In the hut it is always a struggle to get to the stove and to get the big pots. The barbeque of the three lamb legs (3 x 1.8 kg) took place outdoor, the sauce (pepper cheese, crème, blue berries and red wine) was made in advance just to be heated and the potatoes need to be boiled. So, we did not occupy to much space in the kitchen. At the time we started with the potatoes the kitchen staff for a fifteen persons group from Italy arrived and started to cook. The started to make three courses dinner but we came first! The dinner was very successful a perfect final night of the fieldwork.
The next day our gropes collected the remaining GPS instruments and the gravity group det the last loop of measurements. Sonja and I took the ring around Askja to retrieve four instruments and Sveinbjörn and Cas took the instruments deployed along the road to the main road. After we had picked up the last GPS instrument in Dyngjufjalladalur we had a decision to make – which road to take: the truly terrible Sudurábotnar or south of Askja passing Dreki. We chose the latter as we still remembered Sudurábotnar. We returned about 6 PM in Reykjahlið. The last night all of us went to Gamli Bærinn for a dinner. The next day we returned to Reykjavik and Elske to Rotterdam by a direct flight from Akureyri.
Hekla
The weather forecast for the 20th of August was favorable for the area around Hekla and four of us Dori, Sonja, Nate and I decided to go. We aimed to measure the tilt station Naefurholt 11 km due west of the summit. This makes the east–west component sensitive for what happens in the magma chamber at 14–16 km deep under Hekla. This put (distance and magma chamber deep) the Naefurholt tilt station at good location also it is accessible all year around. The measurements went well in the wind, with the instrument placed low. It was good for the measurements but bad for the back! The result showed the cumulative uplift is about (slightly lower) the same as last year. The volcano is still swelling with magma, so there is still hope for an eruption.
The night before I left Iceland on the 22nd the long-awaited eruption started at 9:26 PM. I had the possibility to observe the lava fountains from the fly bus en route to the airport. It was still dark at 4:50 AM but nevertheless, the volcanic show was fantastic. An excellent goodbye for this time marking the end of a very productive trip.
The GPS site Vikraborgir, with Sonja about to measure the antenna height. This is also a gravity point and we took it down in the morning the 10th at the same time Elske and her group started the measurements.
The 1875 explosion crater Víti.
The slippery slope “track” down to the Víti Lake. This “tack” is tricky in rain as the mud gets wet and slippery. The pH in the water is 2.3 which is in the lover end for lemon juice
The stove in in the hut Dyngja started to burn a little too much. This was due to oil had leaked down to the base and started to burn.
The leveling setup with two invar rods placed on fixed benchmarks with the instrument in-between. The distance between the benchmarks is usually 50–60 meters. Note this is a composite illustration to show the setup.
The explosive Plinian eruption in the spring 1875 deposited pumice on the snow. The snow is now ice, and it melts slowly and create cavities under the pumice. Eventually they collapse and some time the ice gets exposed. The opening is about ½ meter wide. The black ash on the top came in the eruption 1961.
The photographer from Reuters documents the old ice.
The rangers and the police get informed of the status of the inflating volcano.
The barbeque party for all the participants and the rangers, this time in the tourist hut.