The Effect of Water Column Resonance on the Spectra of Secondary Microseism P Waves

• Published in: Journal of Geophysical Research: Solid Earth
• Main Authors: Meschede, Matthias, Stutzmann, Éléonore, Farra, Véronique, Schimmel, Martin, 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)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2017
• Subjects: secondary microseisms; body waves; noise source spectra; ocean waves; site effect; [SDU]Sciences of the Universe [physics]; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; North Atlantic
• Online Access: https://insu.hal.science/insu-03682733; https://insu.hal.science/insu-03682733/document; https://insu.hal.science/insu-03682733/file/JGR%20Solid%20Earth%20-%202017%20-%20Meschede%20-%20The%20Effect%20of%20Water%20Column%20Resonance%20on%20the%20Spectra%20of%20Secondary%20Microseism%20P%20Waves.pdf; https://doi.org/10.1002/2017JB014014

International audience We compile and analyze a data set of secondary microseismic P wave spectra that were observed by North American seismic arrays. Two distinct frequency bands, 0.13-0.15 Hz and 0.19-0.21 Hz, with enhanced P wave energy characterize the data set. Cluster analysis allows to classify the spectra and to associate typical spectral shapes with geographical regions: Low-frequency-dominated spectra (0.13-0.15 Hz) are mostly detected in shallower regions of the North Atlantic and the South Pacific, as well as along the Central and South American Pacific coast. High-frequency-dominated spectra (0.19-0.21 Hz) are mostly detected in deeper regions of the northwestern Pacific and the South Pacific. For a selected subset of high-quality sources, we compute synthetic spectra from an ocean wave hindcast. These synthetic spectra are able to reproduce amplitude and shape of the observed spectra, but only if P wave resonance in the water column at the source site is included in the model. Our data sets therefore indicate that the spectral peaks at 0.13-0.15 Hz and 0.19-0.21 Hz correspond to the first and second harmonics of P wave resonance in the water column that occur in shallower ocean depths (<3,000 m) and in the deep ocean (∼5,000 m), respectively. This article demonstrates the important effect of water column resonance on the amplitude and frequency of P waves that are generated by secondary microseisms and that the amplitude of high-quality sources can be predicted from ocean wave hindcasts within a factor of 0.4-6.