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| Deen, M.; Wielandt, E.; Stutzmann, Eleonore; Crawford, W.; Barruol, G.; Sigloch, K.. |
| The Earth's hum is the permanent free oscillations of the Earth recorded in the absence of earthquakes, at periods above 30 seconds. We present the first observations of its fundamental spheroidal eigenmodes on broadband Ocean Bottom Seismometers (OBS) in the Indian Ocean. At the ocean bottom, the effects of ocean infragravity waves (compliance) and seafloor currents (tilt) overshadow the hum. In our experiment, data are also affected by electronic glitches. We remove these signals from the seismic trace by subtracting average glitch signals; performing a linear regression and using frequency-dependent response functions between pressure, horizontal and vertical seismic components. This reduces the long period noise on the OBS to the level of a good land... |
| Tipo: Text |
Palavras-chave: Hum; Noise; Continuous oscillations; Broadband ocean bottom seismology; Surface waves; Glitch. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00407/51841/52446.pdf |
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| Deen, M.; Stutzmann, Eleonore; Ardhuin, Fabrice. |
| The Earth's hum is the continuous oscillations of the Earth at frequencies between 2 and 20 mHz in the absence of earthquakes. The hum strongest signal consists mainly of surface waves. These seismic waves can be generated by infragravity waves propagating over a sloping ocean bottom close to the coast. So far, this theory has only been tested quantitatively using European seismic stations. We use seismic data recorded all around the Indian Ocean together with an ocean wave model that provides time‐frequency varying hum sources. We show that seasonal variations of the hum sources are smaller in the southern hemisphere (SH) than the northern hemisphere (NH). Using these sources, we model Rayleigh wave RMS amplitudes in the period band 3.5‐20 mHz, and the... |
| Tipo: Text |
Palavras-chave: Seismic hum; Infragravity waves; Indian Ocean; Seismic noise; Hum sources; Modeling. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00455/56678/58435.pdf |
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| Stähler, S. C.; Sigloch, K.; Hosseini, K.; Crawford, W. C.; Barruol, G.; Schmidt-aursch, M. C.; Tsekhmistrenko, M.; Scholz, J.-r.; Mazzullo, A.; Deen, M.. |
| RHUM-RUM is a German-French seismological experiment based on the sea floor surrounding the island of La Réunion, western Indian Ocean (Barruol and Sigloch, 2013). Its primary objective is to clarify the presence or absence of a mantle plume beneath the Reunion volcanic hotspot. RHUM-RUM's central component is a 13-month deployment (October 2012 to November 2013) of 57 broadband ocean bottom seismometers (OBS) and hydrophones over an area of 2000 × 2000 km2 surrounding the hotspot. The array contained 48 wideband OBS from the German DEPAS pool and 9 broadband OBS from the French INSU pool. It is the largest deployment of DEPAS and INSU OBS so far, and the first joint experiment. This article reviews network performance and data quality: of the 57... |
| Tipo: Text |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00312/42292/41624.pdf |
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