Dynamic strain determination using fibre-optic cables allows imaging of seismological and structural features.

Natural hazard prediction and efficient crust exploration require dense seismic observationsboth in time and space. Seismological techniques provide ground-motion data, whoseaccuracy depends on sensor characteristics and spatial distribution. Here we demonstratethat dynamic strain determination is possible with conventional fibre-optic cables deployedfor telecommunication. Extending recently distributed acoustic sensing (DAS) studies, wepresent high resolution spatially un-aliased broadband strain data. We recorded seismicsignals from natural and man-made sources with 4-m spacing along a 15-km-long fibre-opticcable layout on Reykjanes Peninsula, SW-Iceland. We identify with unprecedented resolutionstructural features such as normal faults and volcanic dykes in the Reykjanes Oblique Rift,allowing us to infer new dynamic fault processes. Conventional seismometer recordings,acquired simultaneously, validate the spectral amplitude DAS response between 0.1 and100 Hz bandwidth. We suggest that the networks of fibre-optic telecommunication linesworldwide could be used as seismometers opening a new window for Earth hazard assess-ment and exploration. [ABSTRACT FROM AUTHOR]