Distributed acoustic sensing on dark telecom fibre for seismology and research
Can the telecom fibre under the road become a seismic array?
Can the telecom fibre under the road become a seismic array?
Yes. From one cabinet, forty kilometres of dark fibre becomes thousands of strain channels at the spacing you choose, time-stamped by GNSS, written in the formats your processing already reads. Several instruments on separate fibres share one clock.
- Quantitative strain rate on every channel, not event flags.
- Gauge length and channel spacing set in software, from one to forty metres and from half a metre up.
- miniSEED and SEG-Y with correct metadata, plus HDF5 for your own pipelines.
- A daily quality report, noise floor per channel group, coupling map, timing continuity, data completeness.
The event, and the signal
- A telecom fibre under the road. Nothing to install along it.
- A distant earthquake sends a wavefront across the fibre. Every half metre feels it in turn.
- Plotted as distance against time, the arrival draws its own curve, timed by GNSS.
Setup
| Fibre | A dark single-mode fibre, telecom or dedicated. Standard G.652 or G.657. |
| Length | Up to forty kilometres single-ended per instrument. |
| Timing | GNSS pulse-per-second and a 10 MHz reference, so arrays of several units line up to the sample. |
| Power | Mains at the cabinet. Continuous acoustics does not duty-cycle. |
| Data | Decimated streams and raw snapshots as standard; continuous raw streaming as an option, sized to your processing. |
The measurement
Short pulses of light go into the fibre and the phase of the light scattered back from each section is tracked over time. Ground motion strains the glass by a few parts per billion and the phase follows it. The instrument turns that into strain rate per channel, stacks channels to the gauge length you choose, and writes the result with GNSS time.
Deliverables
- miniSEED and SEG-Y archives with station metadata per channel group
- Daily quality report and coupling map along the route
- Dashboard with live waterfall and noise floor
- Raw snapshots on request for method work
On the dashboard, through the API, and as files. All three, always.
Asked before
- Which gauge length should I use?
- It is a software setting, so start at ten metres for earthquakes and go shorter for near-surface work. The raw snapshots let you try both after the fact.
- Can I run my own processing?
- That is the point. The data arrives in miniSEED and SEG-Y, and the quality report tells you which channels to trust.
- Can it share a fibre with live traffic?
- No. It needs a dark fibre. A dark fibre in the same cable as live traffic is fine.
Other things the same box does
- Pipelines and district heating
Where is the leak, before the road sinks? Hot water, cold water or gas.
You get A per-metre temperature baseline for the route, with every persistent deviation located to the half metre.
Read more - Wells
Where is the injected fluid going, and is the well behaving?
You get Time-lapse temperature profiles against the pre-injection baseline, with injection and shut-in periods marked.
Read more - Streams and lakes
Where does groundwater enter the stream, and how much?
You get Inflow zones marked along the reach, ranked by strength, from the damping and phase lag of the daily cycle.
Read more
Put your fibre to work.
Tell us about your fibre and your question. You get a call, a plan for your site and a monthly price.