Global observations of an up to 9 day long, recurring, monochromatic seismic source near 10.9 mHz associated with tsunamigenic landslides in a Northeast Greenland fjord
- 1University of Oxford, Department of Earth Sciences, Oxford, United Kingdom (paula.koelemeijer@earth.ox.ac.uk)
- 2Institute of Geodesy, University of Stuttgart, Germany (widmer@gis.uni-stuttgart.de)
- 3Geological Survey of Denmark and Greenland, Denmark
- 4Department of Earth Sciences, University College London, UK
- 5Geophysical Institute, Karlsruhe Institute of Technology (KIT), Germany
- 6Seismology - Gravimetry, Royal Observatory of Belgium, Brussels, Belgium
- 7Université Paris Cité, Institut de physique du globe de Paris, CNRS, Paris F-75005, France
- 8Institut Terre et Environnement de Strasbourg (ITES), CNRS UMR 7063, Université de Strasbourg, Strasbourg, France
- 9U.S. Geological Survey, Albuquerque, New Mexico, USA
- 10Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, Univ. Gustave Eiffel, ISTerre, 38000 Grenoble, France
- 11Institute of Geophysics, Centre for Earth System Research and Sustainability (CEN), Universität Hamburg, Hamburg, Germany
- 12Arctic Research Centre, Department of Biology, Aarhus University, Denmark
- 13Flanders Marine Institute, Belgium
- 14Norges Geotekniske Institutt, Norway
- *A full list of authors appears at the end of the abstract
We report the discovery of an unprecedented, monochromatic low-frequency seismic source arising from the fjords of North-East Greenland. Following a landslide and tsunami event in Dickson fjord on 16 September 2023, the seismic waves were detected by broad-band seismometers worldwide. Here we focus on a detailed analysis of the long-period seismic signal, while a reconstruction of the dynamics of the landslide is presented by Svennevig et al. in session NH3.5.
Both frequency and phase velocity of the waves are consistent with fundamental mode Rayleigh- and Love-waves. However, the decay rate of these waves is much slower than predicted for freely propagating surface waves so that we infer a long-lasting and slowly decaying source process. Although the 16 September 2023 event was by far the largest, analysis of historical seismic data has revealed five other previously undetected events, all with a fundamental frequency between 10.85 and 11.02 mHz. The signal of the largest two events initially decayed with a quality factor, Q close to Q=500, which increased to Q=3000 within the first 10 hours and could thus be detected for up to nine days. The smaller four events had a slow decay-rate (Q>1000) for their entire duration. In comparison, the global average attenuation of Rayleigh waves at these frequencies is Q=117 for PREM, thus precluding a single, impulsive source for these signals.
Gleaning archives of optical and SAR satellite images reveals that at least four out of six events could be associated with landslides in Dickson fjord, the two others remain unresolved. However, such rapid transient events cannot explain the long duration of the radiated seismic waves. Our modelling of the largest event shows that a transversal seiche in Dickson fjord, excited by a landslide induced tsunami, can account for both the monochromatic low frequency signal as well as its seismic signal amplitude and radiation pattern. However, the seiche modelling results in Q values lower than 250 and hence the seiche needs to be continuously driven for the entire duration of the observed seismic signal. Thus, a full understanding of the source process that produces the monochromatic signal remains enigmatic.
Koen Van Noten, (koen.vannoten@seismology.be ), Seismology - Gravimetry, Royal Observatory of Belgium, Brussels, Belgium, Jelle Assink, (jelle.assink@knmi.nl ), Royal Netherlands Meteorological Institute (KNMI), Netherlands, Alexis Marboeuf , (marboeuf@ipgp.fr ), Université Paris Cité, Institut de physique du globe de Paris, CNRS, Paris F-75005, France, Anthony Lomax, (anthony@alomax.net ), ALomax Scientific, Mouans Sartoux, France, Kris Vanneste, (kris.vanneste@oma.be ), Seismology - Gravimetry, Royal Observatory of Belgium, Brussels, Belgium, Belgium, Taka'aki Taira, (taira@berkeley.edu ), Berkeley Seismological Laboratory, University of California Berkeley, US, Matteo Spagnolo, (m.spagnolo@abdn.ac.uk ), School of Geosciences, University of Aberdeen, UK, Raphael De Plaen, (raphael.deplaen@seismology.be ), Seismology - Gravimetry, Royal Observatory of Belgium, Brussels, Belgium, Belgium, Carl Ebeling, (cebeling@ucsd.edu ), Institute of Geophysics and Planetary Physics, University of California San Diego, US, Andrea Cannata, (andrea.cannata@unict.it ), Università di Catania, Dipartimento di Scienze Biologiche, Geologiche e Ambientali – Sezione di Scienze della Terra, Italy, William Harcourt, (william.harcourt@abdn.ac.uk ), School of Geosciences, University of Aberdeen, UK, David Cornwell, (d.cornwell@abdn.ac.uk ), School of Geosciences, University of Aberdeen, UK, Corentin Caudron, (corentin.caudron@ulb.be ), Université libre de Bruxelles, Belgium, Piero Poli, (piero.poli@unipd.it ), University of Padova, Italy, Pascal Bernard, (bernard@ipgp.fr ), Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, Paris F-75005, France, Eric Larose, (eric.larose@univ-grenoble-alpes.fr ), Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, Univ. Gustave Eiffel, ISTerre, 38000 Grenoble, France, Eleonore Stutzmann, (stutz@ipgp.fr ), Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, Paris F-75005, France, Peter Voss, (pv@geus.dk ), Geological Survey of Denmark and Greenland , Denmark, Bjorn Lund, (bjorn.lund@geo.uu.se ), Department of Earth Sciences, Uppsala University, Sweden, Flavio Cannavo, (flavio.cannavo@ingv.it ), Istituto Nazionale di Geofisica e Vulcanologia, Catania, Italy, Manuel J. Castro-Díaz, (mjcastro@uma.es ), University of Malaga, Spain, Esteban Chaves, (esteban.j.chaves@una.cr ), Volcanological and Seismological Observatory of Costa Rica, OVSICORI-UNA, Costa Rica, Trine Dahl-Jensen, (tdj@geus.dk ), Geological Survey of Denmark and Greenland , Denmark, Nicolas De Pinho Dias, (depinhodias@ipgp.fr ), Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, Paris F-75005, France, Aline Déprez , (depreza@unistra.fr ), Data-Terra / Theia, CNRS UAR 2013, Strasbourg, France, Roeland Develter, (roeland.develter@vliz.be ), Flanders Marine Institute, Belgium, Douglas Dreger, (ddreger@berkeley.edu ), Berkeley Seismological Laboratory, University of California Berkeley, US, Läslo Evers, (evers@knmi.nl ), Royal Netherlands Meteorological Institute (KNMI), Netherlands, Enrique D. Fernández-Nieto, (edofer@us.es ), University of Sevilla, Spain, Ana Ferreira, (a.ferreira@ucl.ac.uk ), Department of Earth Sciences, University College London, UK, Gareth Funning, (gareth@ucr.edu ), University of California, Riverside, US, Alice-Agnes Gabriel, (algabriel@ucsd.edu ), Scripps Institute of Oceanography, University of California San Diego, US, Marc Hendrickx, (marc.hendrickx@oma.be ), Seismology - Gravimetry, Royal Observatory of Belgium, Brussels, Belgium, Belgium, Alan Kafka, (kafka@bc.edu ), Weston Observatory, Boston College , US, Marie Keiding, (mke@geus.dk ), Geological Survey of Denmark and Greenland , Denmark, Jeffrey Kerby, (jkerby@bio.au.dk ), Arctic Research Centre, Department of Biology, Aarhus University, Denmark, Shfaqat Khan, (abbas@space.dtu.dk ), Department of Space Research and Technology, Technical University of Denmark, Denmark, Andreas Kjær Dideriksen, (akd@bio.au.dk ), Arctic Research Centre, Department of Biology, Aarhus University, Denmark, Oliver Lamb, (o.lamb@gns.cri.nz ), GNS Science | Te Pū Ao, Wairakei Research Centre, 114 Karetoto Road, RD4, Taupō 3384, New Zealand, New Zealand, Tine Larsen, (tbl@geus.dk ), Geological Survey of Denmark and Greenland , Denmark, Bradley Lipovsky, (bpl7@uw.edu ), University of Washington, Seattle, US, Ikha Magdalena, (ikha.magdalena@itb.ac.id ), Institut Teknologi Bandung, Bandung, Indonesia, Jean-Philippe Malet , (jeanphilippe.malet@unistra.fr ), Institut Terre et Environnement de Strasbourg (ITES), CNRS UMR 7063, Université de Strasbourg, France, Mikkel Myrup, (mikkel@natmus.gl ), Greenland National Museum & Archives, Greenland, Luis Rivera, (luis.rivera@unistra.fr ), University of Strasbourg, Strasbourg, France, Eugenio Ruiz-Castillo, (eruizcas@bio.au.dk ), Arctic Research Centre, Department of Biology, Aarhus University, Denmark, Selina Wetter, (wetter@ipgp.fr ), Université Paris Cité, Institut de Physique du Globe de Paris, CNRS, Paris F-75005, France, Bastien Wirtz, (b.wirtz@unistra.fr ), Institut Terre et Environnement de Strasbourg (ITES), CNRS UMR 7063, Université de Strasbourg, France
How to cite: Koelemeijer, P., Widmer-Schnidrig, R., Svennevig, K., Hicks, S., Forbriger, T., Lecocq, T., Mangeney, A., Hibert, C., Korsgaard, N., Lucas, A., Satriano, C., Anthony, R., Mordret, A., Schippkus, S., Rysgaard, S., Boone, W., Gibbons, S., Cook, K., Glimsdal, S., and Løvholt, F. and the VLPGreenland team: Global observations of an up to 9 day long, recurring, monochromatic seismic source near 10.9 mHz associated with tsunamigenic landslides in a Northeast Greenland fjord, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5821, https://doi.org/10.5194/egusphere-egu24-5821, 2024.
