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Friedrich, Anke; Krüger, Frank; Klinge, K.

doi:10.1023/a:1009788904007

Cited by 250 publications

(45 citation statements)

References 13 publications

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“…[3] Friedrich et al [1998] first used two arrays in Northern Europe to locate the secondary microseism sources. They found a stationary source close to the coast in the Norway Sea that was independent of the oceanic storm location.…”

Section: Introductionmentioning

confidence: 99%

Global climate imprint on seismic noise

Stutzmann

Schimmel

Patau

et al. 2009

Geochem Geophys Geosyst

128

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[1] In the absence of earthquakes, oceanic microseisms are the strongest signals recorded by seismic stations. Using the GEOSCOPE global seismic network, we show that the secondary microseism spectra have global characteristics that depend on the station latitude and on the season. In both hemispheres, noise amplitude is larger during local winter, and close to the equator, noise amplitude is stable over the year. There is an excellent correlation between microseism amplitude variations over the year and changes in the highest wave areas. Considering the polarization of the secondary microseisms, we show that stations in the Northern Hemisphere and close to the equator record significant changes of the secondary microseism source azimuth over the year. During Northern Hemisphere summer, part or all of the sources are systematically located farther toward the south than during winter. Stations in French Guyana (MPG) and in Algeria (TAM) record microseisms generated several thousand kilometers away in the South Pacific Ocean and in the Indian Ocean, respectively. Thus, secondary microseism sources generated by ocean waves which originate in the Southern Hemisphere can be recorded by Northern Hemisphere stations when local sources are weak. We also show, considering a station close to Antarctica, that primary and secondary microseism noise amplitudes are strongly affected by changes of the sea ice floe and that sources of these microseisms are in different areas. Microseism recording can therefore be used to monitor climate changes.Components: 5366 words, 7 figures.

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Section: Introductionmentioning

confidence: 99%

Global climate imprint on seismic noise

Stutzmann

Schimmel

Patau

et al. 2009

Geochem Geophys Geosyst

128

View full text Add to dashboard Cite

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“…Some studies propose that ground motions are induced in shallow water regions like continental shelves (Friedrich et al 1998;Bromirski et al 1999;Bromirski and Duennebier 2002;Bromirski 2001;Essen et al 2003;Rhie and Romanowicz 2006;Kedar and Webb 2005; Bromirski and Gerstoft 2009). Other scientists propose that the source region is under or trailing a typhoon (Cessaro 1994;Stehly et al 2006;Chevrot et al 2007;Kedar et al 2008;Gerstoft et al 2008;Koper and de Foy 2008;Landes et al 2010;Chi et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Seismic monitoring of western Pacific typhoons

et al. 2010

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Typhoons inflict large damage to societies, but are usually difficult to monitor in close proximity in realtime without expensive instruments. Here we study the possibility of using seismic waveforms on the seafloor and on land to monitor the turning of a far away or approaching typhoon. Up to 67% of the typhoons making landfall in Taiwan come from the eastern shore, so that we deployed broadband ocean-bottom seismometers (OBSs) offshore eastern Taiwan in 2006 to study ground motion in close proximity to a typhoon. Typhoons generate ocean waves, which generate pressure signals in the water column before being transmitted to the seafloor as seismic waves and recorded by the OBSs. The ground motions on the seafloor correlate with locally increased (ocean) wave heights and wave periods, suggesting that the ground motions are mostly induced by in situ or nearby pressure fields, as shown by coherence function analyses. When a typhoon turns and changes wave-wave interaction near the source region, a new set of en echelon patterns develops which can be observed by OBSs and land stations. Similar features occur when a typhoon crosses a landmass and re-enters the ocean. The energy level ratio between the single-frequency and double-frequency microseisms also changes abruptly when the typhoon turns. These features can potentially help near real-time early warning with little cost to complement other conventional typhoon early warning methods.

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“…Ambient seismic noise is additionally randomized by scattering from heterogeneities within Earth (18). Surface-waves are most easily extracted from the ambient noise (5) because they dominate the Green function between receivers located at the surface and also because ambient seismic noise is excited preferentially by superficial sources, such as oceanic microseisms and atmospheric disturbances (19)(20)(21)(22). The seismic noise field is often not perfectly isotropic and may be dominated by waves arriving from a few principal directions.…”

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confidence: 99%