Global scale analysis and modeling of primary microseisms

• Main Authors: Gualtieri, L., Stutzmann, E., Juretzek, C, Hadziioannou, C, Ardhuin, Fabrice
• Other Authors: Institut de Physique du Globe de Paris (IPGP), Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Université de La Réunion (UR)-Institut de Physique du Globe de Paris (IPG Paris)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Océanographie Physique et Spatiale (LOPS), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), ANR-14-CE01-0012,MIMOSA,Analyse, modélisation et utilisation du bruit sismique large bande: des microséismes aux oscillations libres de la terre(2014), ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2019
• Subjects: Seismic noise; Numerical modeling; Computational seismology; Theoretical Seis- mology; [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph]; North Atlantic
• Online Access: https://hal.science/hal-02406006; https://hal.science/hal-02406006/document; https://hal.science/hal-02406006/file/Gualtieri_etal_GJI2019.pdf; https://doi.org/10.1093/gji/ggz161/5421624

International audience Primary microseism is the less studied seismic background vibration of the Earth. Evidence points to sources caused by ocean gravity waves coupling with the seafloor topography. As a result, these sources should be in water depth smaller than the wavelength of ocean waves. Using a state-of-the-art ocean wave model, we carry out the first global-scale seismic modeling of the vertical-component power spectral density of primary mi-croseisms. Our modeling allows us to infer that the observed weak seasonality of primary microseisms in the southern hemisphere corresponds to a weak local seasonality of the sources. Moreover, a systematic analysis of the source regions that mostly contribute to each station reveals that stations on both the East and West sides of the North Atlantic Ocean are sensitive to frequency-dependent source regions. At low frequency (i.e., 0.05 Hz), the dominant source regions can be located thousands of kilometers away from the stations. This observation suggests that identifying the source regions of primary micro-seisms as the closest coasts can be misleading.