SUBMERSE project makes an impact at EGU24

Chris Atherton of SUBMERSE presents at EGU24

During spring every year, Vienna is awash with scientists.

They are attending the largest geoscience conference in Europe, running since 2004.  The 2024 event, EGU24, was bigger than previous years, attracting 21,000 scientists from all over the world to talk about earth, planetary and space-related science.

This is not the first time I’ve attended EGU, but I really was blown away by the sheer scale and breadth of things being discussed this year. Six days of science, cramming in 18,896 presentations over 1,044 sessions.

My reason for being there was to present about the SUBMERSE project and some of the successes that we’ve had. But the conference is huge, taking up four floors of conference centre and a separate exhibition building, all of which sits next to the United Nations campus in Vienna. The conference is so big it has its own artist in residence for the week, who explores ways to express some of the latest discoveries from around the world in an engaging, non-technical way.

Sadly, since Covid, EGU no longer offers the postcard service, where you can send a postcard to anywhere in the world for free. This was always a bit of a novelty, to be able to send a quick message to my family in a format we often view as nostalgic. I still like the idea of sending physical things to people, there’s something about the tangibility of a letter or a postcard that gives the message extra meaning. But I digress from my point.  In a post-Covid world where long established conference formats are trying to return to the way things were, some things have permanently changed.

Fibre sensing in the geoscience community

Chris Atherton presents at EGU

As I was only there for one full day, all of the sessions I attended were focused on things which could help SUBMERSE. Fibre sensing is a topic which is growing in prominence in the geoscience community, with a whole day of sessions just focused on distributed acoustic sensors. One thing about EGU, now that it has grown so big, is that presenters have a very limited time to get straight to the point of the research achievements. This makes it very difficult to provide background and supplementary information to frame the research discovery. This also makes it very engaging for the audience, you have to pay attention, or you will miss a crucial bit of detail. Presentation topics were mixed and varied, with talks about a former underground mine which has been converted into a quiet environment laboratory, DAS results from bore hole drilling, and signals analysis about how DAS shows different results depending on the frequency you are looking at the data with.

Deploying DAS with production DWDM traffic

My presentation was focused on giving an overview of the project and sharing the discovery that we’ve been able to deploy DAS signals in harmonious coexistence with production dense wavelength division multiplexing (DWDM) traffic, over a telecoms fibre. This really is a fantastic achievement of the project so far and vindicates the work and effort that was made in putting together a research project such as SUBMERSE. Through this achievement, we can now utilise any live DWDM cable for the purposes of acquiring DAS measurements. Prior to this it was only possible in the laboratory or using so called dark fibre, essentially un-used fibre cables. Using an entire fibre for sensing purposes is extremely costly, especially if you consider that most optical fibre that is laid is for telecoms purposes.

Telecoms cables have an established business model, especially when using DWDM over the fibre. DWDM is a technique which allows multiple optical channels carrying hundreds of gigabytes of data per second to be mixed together in a way to run all of them over a single fibre pair at the same time. This allows one cable to pass over a terabyte of data per second. At least, this is the current rate of transmission. As technology advances, we’ve been able to carry more and more traffic over single fibre pairs, thereby reducing the cost of operation over time. So, to take one entire fibre pair up between two points for the purposes of deploying just one DAS means that the cost for renting that fibre remains fixed for a long time. It costs quite a bit of money to rent that fibre for a long time, it costs even more to rent for a shorter period.

You may think, if it’s so expensive to run a DAS over a dark fibre, why haven’t we done this before?  Part of the reason is due to uncertainty and no one wanting to take the risk because it is so expensive if it goes wrong. Injecting a DAS signal can be dangerous, as you are essentially injecting a high-powered laser into the fibre cable. This laser can burn out the optics of the DWDM equipment which carries the production traffic, which are also costly and complicated to replace. Most commercial internet service providers don’t want to risk putting their existing telecommunications business and equipment in harm’s way to prove that something can be done. So, a lot of lab tests are required to verify that the technique is possible. This is exactly what the team at Sikt have been doing, with the help of ASN who developed the DAS interrogator. And then from that, it culminated in a field trial of the setup on a terrestrial cable first, before then being deployed on the submarine cable system in Svalbard.

Svalbard showing excellent results, Greece and Portugal next

The setup we now have in Svalbard for collecting data is excellent. Four DAS units across two different geographical sites, multiple polarimeters, and time synchronisation with a technique called white rabbit which includes using an atomic clock.

Our focus as a project is now on getting the other sites set up in a similar way and working on getting the data dissemination side of things going. With DAS units on their way to Greece and Portugal and polarimeters standing by for deployment in those locations too, it shouldn’t be long until we have a similar set up in those other countries.

Following the presentation there were lots of side meetings and discussions with scientists interested in the SUBMERSE project. One thing is key for this community, they need the data from the instruments. During a poster session later in the day I was talking to one of the researchers who had been listening to my presentation. He described the achievements we’ve made in the project so far as a game changer. It put in to focus just how much of an impact we can make with the other sites up and running with instruments too.

Overall, EGU was an extremely useful event to be at. Next time, we hope to be at the event longer, and to have more people from the project present, to cover some of the other topics being discussed such as earth observation from satellites, data movement challenges, planetary science, and research infrastructure support.

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