Sources of secondary microseisms in the Indian Ocean

Davy, Céline; Stutzmann, É.; Barruol, Guilhem; Fontaine, Fabrice R.; Schimmel, Martin

doi:10.1093/gji/ggv221

Cited by 26 publications

(29 citation statements)

References 48 publications

(65 reference statements)

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“…As already observed for secondary microseisms (e.g. Koper & de Foy 2008;Stutzmann et al 2012;Davy et al 2015), the sources around India experience a strong seasonality typical of the southern hemisphere.…”

Section: Seasonal Variationssupporting

confidence: 65%

Global scale analysis and modelling of primary microseisms

Gualtieri

Stutzmann

Juretzek

et al. 2019

Geophysical Journal International

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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 modelling of the vertical-component power spectral density of primary microseisms. Our modelling 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 frequencydependent source regions. At low frequency (i.e. 0.05 Hz), the dominant source regions can be located thousands of kilometres away from the stations. This observation suggests that identifying the source regions of primary microseisms at the closest coasts can be misleading.

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Section: Seasonal Variationssupporting

confidence: 65%

Global scale analysis and modelling of primary microseisms

Gualtieri

Stutzmann

Juretzek

et al. 2019

Geophysical Journal International

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“…In this case, the SM increase recorded on the island can be considered as a warning and precursor of the swell generated by the storm, which takes usually about 3-4 d to propagate northeastwards before reaching La Réunion Island. The source of this noise is located in the southern Ocean, as demonstrated by Davy et al (2015) from the analysis of permanent seismic stations located in the Indian Ocean and also modelled from wave dynamics (Ardhuin et al 2011;. This particular swell event was recently analysed at the seismic stations located in the Mozambique channels (Barruol et al 2016) and the map of this swell propagation in the SW Indian Ocean was presented in their Fig.…”

Section: Austral Swell-related Seismic Noise Recorded By a Seismologimentioning

confidence: 95%

“…SM noise sources have been located in near-coastal shallow waters, related to coastal swell reflection with the incident swell (Bromirski & Duennebier 2002;Bromirski et al 2013), but also in deep waters, related to interactions between swells from two distinct storms Beucler et al 2014). For the Indian Ocean, it has been recently shown that the dominant SM sources are located at large latitudes in the south of the ocean basin, associated with large atmospheric low-pressure systems moving from west to east around Antarctica (Davy et al 2015), but also that SM can be generated by major tropical storms occurring at intermediate latitudes in tropical regions (Davy et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Analyses of extreme swell events on La Réunion Island from microseismic noise

Davy¹,

Barruol²,

Fontaine³

et al. 2016

Geophys. J. Int.

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S U M M A R YOcean wave activity excites seismic waves that propagate through the solid earth, known as microseisms, which, once recorded on oceanic islands, can be used to analyse the swell. Here, we analyse the microseismic noise recorded in different period ranges by the permanent seismic station RER on La Réunion Island and by a temporary network of 10 broad-band seismic stations deployed on the island to analyse extreme swell events. We perform a comparative analysis of cyclonic and austral swell events by analysing not only the primary (PM, ∼10-20 s period) and secondary (SM, ∼3-10 s) microseisms but also the long-period secondary microseisms (LPSMs, ∼ 7-10 s), which may result from the interaction between incident ocean waves and the reflected waves off the coast. We compare the microseismic observations with buoy data when available and with hindcasts from numerical ocean wave models. We show that each cyclone is characterized by its own individual signature in the SM, which depends not only on its distance and intensity but also on its dynamics and trajectory. Thus, the SM contains relevant information for cyclone detection and monitoring. Analysing the PM and the LPSM, and comparing it to direct buoy observations and/or wave numerical models allows characterizing the local impact of the swell with the island in terms of amplitude, period, and sometimes, direction of propagation, making possible to use a seismic station as an ocean wave gauge. The microseisms, which link the atmosphere, the ocean and the solid Earth, can thus provide valuable observations on extreme swell events, in addition to oceanic and meteorological data.

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“…The SFMs are generally believed to be generated by the direct impact of ocean waves on the ocean floor (Ardhuin et al, ; Barruol et al, ; Cessaro, ; Hasselmann, ), while the DFMs require the interaction of opposing wavefields that have nearly the same wave number, which generates a pressure excitation pulse at twice the wave frequency acting on the ocean floor (e.g., Ardhuin et al, ; Bromirski et al, ). Although the causal mechanisms of SFMs and DFMs are well accepted, their source locations and wave types are still under investigation, and an unified theory explaining all the observations has not been achieved yet (Behr et al, ; Chen et al, ; Chevrot et al, ; Davy et al, ; Diez et al, ; Gerstoft & Tanimoto, ; Gualtieri et al, ; Landes et al, ; Möllhoff & Bean, ; Nishida et al, ; Obrebski et al, ; Reading et al, ; Sergeant et al, ; Sufri et al, ).…”

Section: Introductionmentioning

confidence: 99%

The Characteristics of Microseisms in South China Sea: Results From a Combined Data Set of OBSs, Broadband Land Seismic Stations, and a Global Wave Height Model

et al. 2018

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It has long been recognized that ocean gravity waves can generate microseisms through their interactions and coupling with the solid earth. Their generation mechanisms, wave types, and propagation have been studied and debated intensively. In this study, we focus on the characteristics of microseisms in South China Sea (SCS) and compare them with globally observed microseisms. We use data from six ocean bottom seismometers, 10 publicly available broadband land seismometers near SCS, and a reanalyzed global wave height model from 1 May 2012 to 20 August 2012 (UTC), the time span of ocean bottom seismometers' data. We apply three techniques including power spectral density, correlation, and frequency dependent polarization analysis. Our results show that (1) microseisms observed in SCS are dominated by sources from adjacent oceans, instead of the common global sources from the Pacific, Atlantic, or Indian Ocean; (2) the split of double-frequency microseisms (DFMs) is observed in SCS, especially on land stations: the sources are located near the central sea basin for long-period DFMs (0.1-0.25 Hz) and are local near stations for short-period DFMs (0.25-0.5 Hz); (3) typhoons both strengthen microseisms and affect the source locations of microseisms with the biggest influence on the short-period DFMs; and (4) microseisms in or near SCS are a mixture of Love and Rayleigh waves and the relative dominance of Love and Rayleigh waves changes with locations.As early as the 1900s when microseisms were still treated as one group, there were mainly two candidates on the source locations: one was coastal region (e.g., Gutenberg, 1931;Haubrich, 1963) and the other was open ocean (e.g., Banerji, 1930; Haq, 1954). Although Stehly et al. (2006) back-projected the source of SFMs to the XIAO ET AL. 3923

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Sources of secondary microseisms in the Indian Ocean

Cited by 26 publications

References 48 publications

Global scale analysis and modelling of primary microseisms

Global scale analysis and modelling of primary microseisms

Analyses of extreme swell events on La Réunion Island from microseismic noise

The Characteristics of Microseisms in South China Sea: Results From a Combined Data Set of OBSs, Broadband Land Seismic Stations, and a Global Wave Height Model

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