The GFZ-Landsvirkjun Theistareykir Fibre array is located in the Theytareykir geothermal area, in North Iceland. It is collocated with arrays of broadband seismometers and gravity meters (see e.g., https://doi.org/10.1186/s40517-021-00208-w). The geometry of the fibre array is following the telecom network in the area, and was chosen to test the seismological capabilities of telecom cables in this geothermal environment. We connected an iDAS V2 interrogator from Silixa. The interrogator location is lat=65.898041, lon=-16.966274.

The array starts N-S and after 1.5 km, turns towards the East, up to a local transmission antenna station for mobile phones. The length of the path is ~5 km. The length of the cable is actually more than 15 km, as other fibre instance is connected at the transmission antenna station.. Jumps were performed along the cable to geo-locate the channels. The exact location of the fibre can unfortunately not be disclosed. Original recordings at 1000 Hz were downsampled to 200 Hz using a software from INGV-OE (michele.prestifilippo@ingv.it) and are provided in an h5 format. We provide here the first fibre instance (5 km long).

The data contain 1 h long recording intervals framing M>5 teleseismic earthquakes recorded in the frame of the global DAS month, an initiative to collaboratively record and share simultaneously recorded DAS data from all over the world (https://www.norsar.no/in-focus/global-das-monitoring-month-february-2023). DAS is an emerging technology increasingly used by seismologists to convert kilometer long optical fibers into seismic sensors.