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| Hable, Sarah; Sigloch, Karin; Barruol, Guilhem; Staehler, Simon C.; Hadziioannou, Celine. |
| Many applications in seismology rely on the accurate absolute timing of seismograms. However, both seismological land stations and ocean bottom seismometers (OBSs) can be affected by clock errors, which cause the absolute timing of seismograms to deviate from a highly accurate reference time signal, usually provided by GPS satellites. Timing problems can occur in land stations when synchronization with a GPS signal is temporarily or permanently lost. This can give rise to complicated, time-dependent clock drifts relative to GPS time, due to varying environmental conditions. Seismometers at the ocean bottom cannot receive GPS satellite signals, but operate in more stable ambient conditions than land stations. The standard protocol is to synchronize an OBS... |
| Tipo: Text |
Palavras-chave: Time-series analysis; Seismic instruments; Seismic interferometry; Seismic noise. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00444/55599/57230.pdf |
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| Hable, Sarah; Sigloch, Karin; Stutzmann, Eleonore; Kiselev, Sergey; Barruol, Guilhem. |
| We use seismic noise cross-correlations to obtain a 3-D tomography model of SV-wave velocities beneath the western Indian Ocean, in the depth range of the oceanic crust and uppermost mantle. The study area covers 2000×2000 km2 between Madagascar and the three spreading ridges of the Indian Ocean, centred on the volcanic hotspot of La Réunion. We use seismograms from 38 ocean bottom seismometers (OBSs) deployed by the RHUM-RUM project and 10 island stations on La Réunion, Madagascar, Mauritius, Rodrigues, and Tromelin. Phase cross-correlations are calculated for 1119 OBS-to-OBS, land-to-OBS, and land-to-land station pairs, and a phase-weighted stacking algorithm yields robust group velocity measurements in the period range of 3-50 s. We demonstrate that OBS... |
| Tipo: Text |
Palavras-chave: Crustal imaging; Seismic instruments; Seismic interferometry; Seismic noise; Seismic tomography. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00508/61988/66099.pdf |
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| Trabattoni, A; Barruol, G; Dreo, R; Boudraa, A O; Fontaine, F R. |
| Breakthroughs in understanding the structure and dynamics of our planet will strongly depend upon instrumenting deep oceans. Progress has been made these last decades in ocean-bottom seismic observations, but ocean-bottom seismometer (OBS) temporary deployments are still challenging and face set-up limitations. Launched from oceanographic vessels, OBSs fall freely and may slightly drift laterally, dragged by currents. Therefore, their actual orientation and location on the landing sites are hard to assess precisely. Numerous techniques have been developed to retrieve this key information, but most of them are costly, time-consuming or inaccurate. In this work, we show how ship noise can be used as an acoustic source of opportunity to retrieve both the... |
| Tipo: Text |
Palavras-chave: Seismic instruments; Seismic noise; Wave propagation; Body waves; Statistical methods; Acoustic properties. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00593/70463/68591.pdf |
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