By detecting underground movements, Eva Eibl is finding key signals that tell us about volcanic eruptions. She spoke to Claire O’Connell.
Volcanic eruptions can wreak havoc, and it’s not only for those who live nearby – remember when, in 2010, eruptions at the tongue-twisting Eyjafjallajökull in Iceland sent out a plume of ash that grounded planes and triggered travel chaos in Europe and beyond?
Having a heads up that an eruption might happen brings obvious advantages and, for geoscientist Eva Eibl, ‘listening’ to underground movements is key to understanding more about the kinds of patterns we need to heed.
What lies beneath
Eibl’s recently completed PhD research at University College Dublin (UCD) involved putting sensitive detectors around volcanoes in Iceland and monitoring what they could tell us about what lies beneath.
“We went to sites in Iceland and we dug holes and poured cement and installed our instruments,” said Eibl. “Then we linked the stations up so we could read their signals in real time when we are sitting in Dublin.”
The idea behind the sensor network, which was part of the EU-funded FutureVolc project, was to keep an ear to the ground for movements beneath the ice and bedrock, and pick up on earthquakes and the flow of magma and water in the volcanic region.
One of the most interesting areas for Eibl’s work was Bárðarbunga, a stratovolcano that started erupting in August 2014, and one of the first signs that something was up was an increase in earthquakes.
“Scientists monitoring the area suddenly realised there were a lot more earthquakes than normal, and the earthquakes also started to migrate – they moved around 50km,” recalled Eibl.
“People were alarmed because the volcano where it all started was beneath a glacier (Vatnajökull) and they were afraid it was like 2010 all over again, where a subglacial volcano erupted and you get ash everywhere.”
In the end, the seismic activity kept moving sideways and the lava eventually surfaced beyond the ice, meaning no ash, but the whole event offered Eibl an interesting case study to analyse the data from the instruments they had installed above ground.
“We have a special set-up for our instruments; seven of them are quite close to each other, so we could analyse the background ‘noise’ of the eruption,” she explained.
“And from our data, we could see a high pulse of signals, a tremor, that started around 2km down and moved up for about 19 hours. We think this continuous analysis of the background signal might be able to offer an early warning that things are moving, and we think it was not the moving magma creating the tremor, but that it is the gradual breaking of the shallow crust, and magma just flows into that space and to the eruption silently.”
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The findings, published in Nature Geoscience this week, knit together some of the puzzles that remain about this volcanic event, including whether there had been some eruptions under the ice as the seismic activity moved along sideways.
“The tremor activity we saw links in with some depressions in the ice that glaciologists saw, so our paper is saying yes, there may have been subglacial eruptions,” said Eibl.
Her work – which she carried out with PhD supervisors Prof Chris Bean and Dr Ivan Lokmer at UCD School of Earth Sciences – should help inform systems that monitor seismic activity, but Eibl advises caution in the field of forecasting seismic events.
“You can’t predict an earthquake or volcanic eruption,” she says. “You can forecast that, say it is 90pc likely that the volcano will erupt in the next two days, and our work can contribute to that.
“But now, we need to do more work to see if we can see these kinds of signals on other volcanoes too; what we have done here is very much a starting point.”
Tips from the field
Eibl gravitated towards volcanoes when she was studying geosciences as an undergraduate and geophysics for her master’s in her native Munich, Germany. “I loved going on field trips and I found I always wanted to go on the volcanology field trips especially,” she said.
She moved to Dublin to work on the Icelandic monitoring project with UCD and is now working with the Dublin Institute for Advanced Studies.
Eibl hopes to continue her work on volcanoes, and has enormous respect for their power, especially when she is out hiking on them. “Some people don’t think about it if they hike on an active volcano, but I am not one of those – I am very aware that you have to be careful,” she said.
“It’s really important to have a guide, and to use GPS so you can find your way down quickly if the weather changes. You have to be very cautious and vigilant. Don’t take your boots off and don’t turn your back on the crater, keep your eye on it!”
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