Observation of deep water microseisms in the North Atlantic Ocean using tide modulations

• Published in: Geophysical Research Letters
• Main Authors: Beucler, Éric, Mocquet, A., Schimmel, Martin, Chevrot, Sébastien, Quillard, Olivier, Vergne, Jérôme, Sylvander, Matthieu
• Other Authors: Laboratoire de Planétologie et Géodynamique UMR 6112 (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institute of Earth Sciences Jaume Almera, Consejo Superior de Investigaciones Cientificas = Spanish National Research Council (CSIC), Dynamique terrestre et planétaire (DTP), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS), Laboratoire de recherche en Hydrodynamique, Énergétique et Environnement Atmosphérique (LHEEA), École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS), Institut de physique du globe de Strasbourg (IPGS), Université de Strasbourg (UNISTRA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de recherche en astrophysique et planétologie (IRAP)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2015
• Subjects: [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph]; North Atlantic
• Online Access: https://hal.science/hal-01277085; https://hal.science/hal-01277085/document; https://hal.science/hal-01277085/file/Beucler2015.pdf; https://doi.org/10.1002/2014GL062347

International audience Key Points: • Tide modulations of the microseismic energy are observed at shoreline stations • Coastal and open-sea microseismic sources coexist in different frequency ranges • Most of the 2–5 s period microseisms on the Atlantic coast come from deep ocean Abstract Ocean activity produces continuous and ubiquitous seismic energy mostly in the 2–20 s period band, known as microseismic noise. Between 2 and 10 s period, secondary microseisms (SM) are generated by swell reflections close to the shores and/or by opposing swells in the deep ocean. However, unique conditions are required in order for surface waves generated by deep-ocean microseisms to be observed on land. By comparing short-duration power spectral densities at both Atlantic shoreline and inland seismic stations, we show that ocean tides strongly modulate the seismic energy in a wide period band except between 2.5 and 5 s. This tidal proxy reveals the existence of an ex situ short-period contribution of the SM peak. Comparison with swell spectra at surrounding buoys suggests that the largest part of this extra energy comes from deep ocean-generated microseisms. The energy modulation might be also used in numerical models of microseismic generation to constrain coastal reflection coefficients.