Global scale analysis and modeling of primary microseisms

Type Article
Date 2019-07
Language English
Author(s) Gualtieri L1, Stutzmann E2, Juretzek C3, 4, Hadziioannou C3, Ardhuin FabriceORCID5
Affiliation(s) 1 : Princeton University, Department of Geosciences, Guyot Hall, Princeton, NJ 08540, USA
2 : Institut de Physique du Globe de Paris, 1 Rue Jussieu, 75005, Paris, France
3 : Institute of Geophysics, Center for Earth System Research and Sustainability (CEN), Universität Hamburg, D-20146 Hamburg, Germany
4 : Department of Earth and Environmental Sciences, Ludwig Maximilian University of Munich, D-80333 Munich, Germany
5 : Univ. Brest, CNRS, Ifremer, IRD, Laboratoire d’Océanographie Physique et Spatiale (LOPS), IUEM, Brest, France
Source Geophysical Journal International (0956-540X) (Oxford University Press (OUP)), 2019-07 , Vol. 218 , N. 1 , P. 560-572
DOI 10.1093/gji/ggz161
WOS© Times Cited 11
Keyword(s) Numerical modelling, Computational seismology, Seismic noise, Theoretical Seismology

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 microseisms. 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 microseisms as the closest coasts can be misleading.

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