Sound generators used in scientific seismic surveys - calibration and modeling
Academic research in the Southern Ocean comprises both high-resolution reflection seismic surveys to study - for instance - the depositional history of fine-scale sedimentary structures and lower-resolution, deep-penetrating reflection and refraction seismic surveys to study - for instance - large s...
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| Format: | Conference Object |
| Language: | unknown |
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2006
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| Online Access: | https://epic.awi.de/id/eprint/15592/ https://hdl.handle.net/10013/epic.25708 |
| Summary: | Academic research in the Southern Ocean comprises both high-resolution reflection seismic surveys to study - for instance - the depositional history of fine-scale sedimentary structures and lower-resolution, deep-penetrating reflection and refraction seismic surveys to study - for instance - large scale crustal structures. These studies are usually embedded in research programs focussing on topics like the geodynamic evolution and the plate tectonic, paleoceanographic and climatic history of the Southern Ocean. Single airguns or airgun arrays of small size and volume and single- and multi-channel streamers are usually used as sound sources and receivers for high-resolution reflection seismic surveys, whereas airguns and airgun arrays of larger size and volume and ocean-bottom-hydrophones and seismometers and single- and multi-channel streamers are usually applied for lower-resolution , deep penetrating reflection and refraction seismic surveys. To ensure that these research activities do not affect marine wildlife and particularly marine mammals in the Southern Ocean adversely knowledge of the sound pressure field of the seismic sources is essential. Therefore, as an example, a broadband marine seismic source calibration study conducted with R/V Polarstern at the Heggernes Acoustic Range, Herdlefjord, Norway in October 2003 is presented here. The objectives were (1) to determine the spatial distribution of the sound pressure levels emitted by the airguns and airgun arrays available at the Alfred-Wegener-Institute for Polar and Marine Research, Bremerhaven, Germany in October 2003, (2) to determine the frequency bandwidth, the spectral peak level and the amplitude decay at higher frequencies, and the cumulative and total energy of the different source signatures, (3) to determine the theoretical, back-projected nominal source levels at 1 m distance from far-field measurements assuming a spherical amplitude spreading, (4) to determine radii, within which according to the presently applied thresholds and the ... |
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