Fiber-Optic Airplane Seismology on the Northeast Greenland Ice Stream

• Published in: The Seismic Record
• Main Authors: Fichtner, Andreas, Hofstede, Coen, Kennett, Brian L. N., Nymand, Niels F., Lauritzen, Mikkel L., Zigone, Dimitri, Eisen, Olaf
• Other Authors: Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology Zürich (ETH Zürich), Alfred Wegener Institute for Polar and Marine Research (AWI), Australian National University (ANU), Niels Bohr Institute Copenhagen (NBI), Faculty of Science Copenhagen, University of Copenhagen = Københavns Universitet (UCPH)-University of Copenhagen = Københavns Universitet (UCPH), Institut Terre Environnement Strasbourg (ITES), École Nationale du Génie de l'Eau et de l'Environnement de Strasbourg (ENGEES)-Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2023
• Subjects: [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology; Greenland; ice core; Ice Sheet
• Online Access: https://hal.science/hal-04357095; https://hal.science/hal-04357095/document; https://hal.science/hal-04357095/file/islandora_168595.pdf; https://doi.org/10.1785/0320230004

We present distributed fiber‐optic sensing data from an airplane landing near the EastGRIP ice core drilling site on the Northeast Greenland Ice Stream. The recordings of exceptional clarity contain at least 15 easily visible wave propagation modes corresponding to various Rayleigh, pseudoacoustic, and leaky waves. In the frequency range from 8 to 55 Hz, seven of the modes can be identified unambiguously. Based on an a priori firn and ice model that matches P‐wave dispersion and the fundamental Rayleigh mode, a Backus–Gilbert inversion yields an S‐wavespeed model with resolution lengths as low as a few meters and uncertainties in the range of only 10 m/s. An empirical scaling from S wavespeed to density leads to a depth estimate of the firn–ice transition between 65 and 71 m, in agreement with direct firn core measurements. This work underlines the potential of distributed fiber‐optic sensing combined with strong unconventional seismic sources in studies of firn and ice properties, which are critical ingredients of ice core climatology, as well as ice sheet dynamics and mass balance calculations.