Strokkur: Why It Stopped Erupting - and the 1963 Drilling That Brought It Back

Strokkur stopped erupting in the autumn of 1896, when earthquakes in South Iceland shifted the plumbing beneath the Haukadalur hot spring field. For sixty-seven years it did almost nothing. On 16 July 1963 a state drilling rig arrived from Selfoss with orders to wake it up. It took eighteen days. At 39 metres, on 23 July, the hole erupted with such force that nobody could get near the rig. Strokkur has erupted ever since.

Strokkur goes off every few minutes — roughly nine times an hour, with something like seven minutes between eruptions on average. The crowd stands in a loose ring behind the rope, phones up, and waits. The water swells into a blue dome a second before it goes, which is the moment everyone is trying to catch and mostly misses.

It is the most reliable geyser in Iceland, and reliability is why it sits on every Golden Circle itinerary in the country, alongside Þingvellir and Gullfoss. What almost nobody standing there knows is that the reliability is recent, and that it was arranged.

This trips up most visitors, and a fair amount of published writing too.

Geysir — the original, the one that gave every geyser in every language its name — is dormant. It has been more or less quiet for decades. What you see there now is a large, still, steaming pool.

Strokkur is a separate hot spring a short walk away. Smaller, and the one actually erupting. Nearly every photograph captioned “Geysir erupting” is Strokkur.

The two are connected underground, and their histories run against each other: through the recorded past, when one has been active the other has tended to be quiet.

The idea of intervening at Strokkur is not modern.

In 1708 Strokkur was deliberately blocked with turf and stones. The reason was agricultural: it was damaging the hayfield at Laug, the farm alongside the hot spring field. A hay meadow was worth more than a spouting hole in the ground.

Worth holding onto that, because the question people ask about 1963 — whether it is acceptable to interfere with a natural feature like this — was answered by the people who lived here 255 years earlier, in the other direction.

In 1789 a strong earthquake struck the region and Strokkur began erupting powerfully.

Four years later, in 1793, the naturalist Sveinn Pálsson recorded the geyser and its name. Strokkur means “churn” — the wooden butter churn, with its plunger driven up and down. Anyone who had made butter recognised the motion immediately.

The nineteenth-century record is a list of heights, and it reads like a decline with interruptions.

1804: around 45 metres, with Geysir reaching 65. 1809: 45 metres again, sustained for something like an hour and a half. 1810: 24 metres. 1815: over 60. By 1830 it was clearly weakening. In 1863 it managed 15 metres — but that eruption was induced, with gravel. By 1871 there was virtually no natural activity at all. In 1880 it was back to 25 or 28 metres.

That word induced is the part usually left out. For much of the nineteenth century Strokkur erupted mainly when people made it. Turf and gravel were thrown into the conduit to choke it and force a reaction, and visitors who had travelled a long way expected a show. The later soaping of Geysir was the same instinct with better chemistry.

So by the time anyone arrives at 1963, the site already has a two-hundred-year history of people reaching into it — first to stop it, then to start it.

In the autumn of 1896 a sequence of earthquakes struck South Iceland, and the hot spring field rearranged itself.

Strokkur stopped almost completely. Geysir took over, erupting powerfully for the next two decades — which is precisely the period when Geysir’s international fame was established.

You will see 1907, 1920 and vague phrases like “around the turn of the century” given as the date Strokkur went quiet. Those are wrong. The event is the 1896 earthquake sequence, and the local record is clear about it.

Sixty-seven years.

Over that time the water level in the conduit fell steadily. In 1931 the water stood about a metre below the surface, with a surface temperature of 80.5 degrees. In 1937 the conduit was measured at 11 metres.

The clearest description of what it had become comes from Kristbergur Jónsson, who lived at Laug. He described a hole around 12 metres deep, narrowing as it went, with no standing water — only a small pool at the very bottom. Part of that account he had from his mother.

That is what was there in the summer of 1963. Not a geyser. A hole with rubble in it.

I met his son. Jón Kristbergsson lived in a turf house that is still standing near Strokkur, and my father took me there when I was eight or nine years old. My father was a tall man and had to bend to get through the doorway. We sat inside and drank black coffee. I was too young to ask him about Strokkur, which I have regretted since.

What I remember is him telling my father how strange he found it that the tourists coming to watch Strokkur had no idea the whole thing was partly man-made. He had been alive when it was not erupting. I do not remember his exact words — I was a boy, and it was a long time ago — but that was the sense of it, and it stayed with me.

Everything written about the 1963 drilling until now has come down to a sentence: locals cleared the blocked conduit on the advice of the Geysir Committee.

The men who did it kept a daily log. Fifteen sheets, one per working day, handwritten in ballpoint on the printed forms of Rafmagnsveitur ríkisins, Jarðborunardeild — the State Electricity Authority’s drilling department. Each one is signed at the bottom by the rig foreman: Þórir Sveinbjörnsson. The same three men are listed alongside him on nearly every sheet — Ólafur J. Jónsson, Reynir Guðmundsson, and a Sigurðsson whose first name I cannot read with confidence.

Those are the “locals.”

The first sheet is dated 16 July 1963. No drilling was done. They moved the rig up from Selfoss, laid water pipes and set up pumps, and the foreman wrote down what they had come to do:

Borinn fluttur frá Selfossi að STROKK í Haukadal, en gera á tilraun með að laga hverinn og vekja hann til lífsins aftur, en hann hefur legið að mestu niðri frá því fyrir 1896.

The rig moved from Selfoss to Strokkur in Haukadalur, to attempt to repair the spring and wake it back to life, it having lain mostly dormant since before 1896.

Note the date in that sentence. In 1963 the men standing at the spring knew perfectly well when it had stopped. It is the modern sources that lost it.

The next day they tried to pump the spring out and found it too hot to work with — 83 degrees. They gave up on pumping, built a timber platform over the hole, and started to drill. By evening they were at 19.5 metres, and the foreman recorded what was down there:

Hitt nú er á vatn 1.60 m. Dýpi í hver 5.60 m. Rusl í botninum frá 5.60 m niður í 12 m.

Water at 1.60 m. Depth of the spring 5.60 m. Rubble in the bottom from 5.60 m down to 12 m.

Those are exactly the figures the local histories give. Here they are in the hand of the man who measured them.

By 19 July they were at 36.4 metres and there were signs of something happening — steam showing from 34 metres down. They pulled the drill string and the hole spat out the water standing in it, with a trace of steam. It was not enough.

So they tried everything else. They took the casing back out. They poured in soap. They added carbide. Nothing.

The next day, 20 July, is the sheet that changes the story:

Gerðar miklar tilraunir til að fá Strokk til að gjósa, en vegna fyrirmæla um að fara “sérstaklega varlega” þá vildum við ekki bora meira í bili fyrr en fullreynt væri hvort hægt væri að ná hvernum til að gjósa. Sett var sápa 45 kg. Sett úr karbít — mikið, en allt kom fyrir ekki.

Great efforts made to get Strokkur to erupt, but because of instructions to proceed “especially carefully” we did not want to drill any further for the time being, until it had been fully tested whether the spring could be made to erupt. 45 kg of soap was added. Carbide added — a great deal — but none of it did any good.

Read that twice. The 1963 drilling is usually told as an era that simply did things. It was not. Somebody gave these men an instruction to go especially carefully, and the foreman thought the phrase worth putting in quotation marks. They stopped drilling and spent three days trying to avoid it.

And they soaped Strokkur. Forty-five kilos. The soaping of Geysir is a well-worn story; nobody mentions that the same thing was tried on Strokkur first, and that it failed.

They went home for the weekend. They came back on Monday 22 July and tried the soap again, and pumping again. The spring sat there, brim full, trickling slightly over the edge, and did nothing.

On the Tuesday they went back down.

Borað með 4¼” krónu niður í 39.40 m, en í 39. m gaus holan mjög öflugu gosi.

Drilled with a 4¼” bit down to 39.40 m, but at 39 m the hole erupted with a very powerful eruption.

They stopped at 39.40 metres. Not because the hole was finished, but because it was no longer possible to get near the rig. They tried to pull the drill string out and managed nine metres before the spring began spitting up under the platform and through the gaps in the boards — while water was being pumped into it at eight to ten litres a second to hold it down.

Sixty-seven years of nothing, a week of soap and carbide and pumping, and then three metres of rock.

What follows in the log is not triumph. It is a week of hard, awkward work trying to get their own equipment back out of an erupting geyser.

They pumped in 15 to 20 litres a second and it was not enough. They mixed heavy drilling mud and pumped that down; the hole threw it straight back. They tried Fiberlex. Same. On 29 July the foreman wrote, with what reads like a mixture of exasperation and admiration:

Hverinn er stórkostlegur vegna gosa uppi gegnum pallinn sem er ofan á hvernum.

The spring is magnificent, erupting up through the platform that is on top of it.

The steel casing — 19.4 metres of 5-inch pipe — was stuck fast. It took them from 25 to 31 July to get it out, and when it finally came free it came up in one piece. This matters, because it means there is no pipe left in Strokkur. The hole is open rock.

That same day, 31 July, the rig was taken away and the platform dismantled. The foreman’s last line on the sheet:

Upp vakinn Strokkur er að vísu skítugur, en gosin eru kröftug ef hverinn fær nóg vatn.

Strokkur, woken up, is admittedly dirty, but the eruptions are powerful if the spring gets enough water.

Two days of clearing up followed. And then, on 3 August, the last sheet records something nobody writing about Strokkur has mentioned since. As the old basin filled and the water level rose, the eruptions changed character: they came further apart, and they got bigger.

Þegar vatnið hækkaði í hvernum þá hækkuðu gosin um leið og urðu strjálli, allt frá því að vera 30 sekúndur á milli gosa upp í 10–15 mínútur milli gosa, og þá komu einka 40–50 m gos. Veður var stillt og auðvelt að bera saman við borsmastrið.

As the water rose in the spring the eruptions rose with it and became less frequent, going from 30 seconds between eruptions to 10–15 minutes, and then came eruptions of some 40–50 m. The weather was calm and it was easy to compare against the drill mast.

Forty to fifty metres. Measured against their own rig mast, on a still day, in the first week of August 1963.

Strokkur has erupted continuously since that August, and it is the borehole that made it dependable rather than occasional.

Measurements since: a flow of about 2.5 litres per second in 1967, and roughly 2 litres per second measured for Iceland’s Nature Conservation Council on 17 September 1994, with water temperature at depth somewhere around 120 to 125 degrees.

It no longer throws water forty metres. What it does instead is go off nine times an hour, every hour, in every weather, which is worth more to a coach schedule than any single spectacular column.

The old habits took a while to die. Geysir was still being coaxed into performing after 1963, and the method was the same soap that had failed at Strokkur — poured in to lower the surface tension and set off an eruption on demand, usually for an audience.

My sport teacher at grammar school was one of the men who soaped Geysir. He went up at night, because it was not really permitted.

The site is now protected. Since 17 June 2020 it has been a protected natural monument, and interventions of the 1963 kind are no longer on the table.

Partly. Honestly, yes, partly.

The heat is natural. The water is natural. The conduit is natural, and it erupted on its own for long stretches of the eighteenth and nineteenth centuries. But the Strokkur you watch today — the one that goes off nine times an hour, reliably enough to build a tour schedule around — exists in that form because four men drilled 39.4 metres into it in the summer of 1963. Without that, it would be a small pool. Roughly what Geysir is now.

That is not a scandal, and it is not a secret. It is the continuation of something that had been going on at this site since at least 1708: people blocking it, choking it, throwing turf into it, soaping it, drilling it. The 1963 borehole is the most successful thing anyone has done to it, not the first.

What strikes me, having read the log, is that they were not reckless. That was what I expected to find and it is not what is there. They had orders to go especially carefully and they followed them — they stopped drilling for three days and tried every gentler thing they could think of first. Only when the pumps and the soap and the carbide had all failed did they go back down, and then it worked immediately.

Nobody would do it now. Geysir sits quiet a short walk away, and the reason nobody drills it is that the ground underneath is not well enough understood to know what a borehole would do to the rest of the field. That caution has been argued out in public, in the newspapers, over years.

So the difference between 1963 and today is not that they were careless and we are careful. They were careful. The difference is that in 1963 being careful still ended with a decision to drill, and a geyser that has run for sixty-three years. I am not sure the modern answer is wrong. But it is worth saying plainly what the cautious answer would have cost in 1963: Haukadalur would have two silent pools and nothing to watch.

None of this was hidden. The drilling reports have been sitting in a public state archive the whole time, scanned and free to download, findable by anyone who thought to look for a borehole rather than a geyser.

The gap in the English-language record was never a missing document. It was that everybody copied everybody else.

Two things in the record I have not been able to settle. The national borehole registry names the rig as Ýmir; the daily sheets appear to name a different rig. And the registry gives the operator as Jarðboranir ríkisins, where the sheets are printed with Rafmagnsveitur ríkisins, Jarðborunardeild. I have left both out of the account above rather than guess. If you know the answer, or if you have a photograph of the work — no image of the 1963 drilling has surfaced anywhere — I would like to hear from you.

Borskýrsla — daily drilling reports, Strokkur, 16 July – 3 August 1963. Rafmagnsveitur ríkisins, Jarðborunardeild. 15 sheets plus cross-section. Digitised by Orkustofnun:

Daily reports, July–August 1963 (PDF)

Borehole cross-section, 8 August 1963 (PDF)

Borholuskrá — the national borehole registry, Umhverfis- og orkustofnun. Borehole 91751, Strokkur í Haukadal.

Ingólfur Guðnason, “Strokkur og hverasvæðið í Haukadal”, Litli-Bergþór, magazine of Ungmennafélag Biskupstungna.

Helgi Torfason, article on Strokkur in Eyjar í eldhafi (1995), festschrift for Jón Jónsson.

Helgi Torfason, “Geysir vakinn upp”, Náttúrufræðingurinn 53 (1–2), 1984, pp. 5–6.

Ísleifur Jónsson, “Hvers vegna sefur Geysir?”, Morgunblaðið, 22 July 1997, pp. 26–27.

Umhverfisstofnun, Stjórnunar- og verndaráætlun — Geysir 2022–2031.