Open Access

Acquisition, processing and analysis of densely sampled P- and S-wave OBS-data on the mid-Norwegian Margin, NE Atlantic

  • Rolf Mjelde1, 5Email author,
  • Tommy Timenes2,
  • Hideki Shimamura3,
  • Toshihiko Kanazawa4,
  • Hajime Shiobara3, 5,
  • Shuichi Kodaira3, 6 and
  • Ayako Nakanishi3, 6
Earth, Planets and Space201454:BF03352451

https://doi.org/10.1186/BF03352451

Received: 11 April 2002

Accepted: 8 November 2002

Published: 21 June 2014

Abstract

This paper describes the processing and analysis of semi-local OBS-data shot along a 122 km profile in the Vøring Basin, NE Atlantic margin, using both a high-frequency/short shot-spacing and a low-frequency/long shot-spacing air-gun source. Spectral analysis of the data reveals that an important difference between the two sources used, is that the low-frequency source generates significantly more energy around 6 Hz. This higher content of very low frequencies allows detection of arrivals to larger offsets for the low-frequency source. For the nearest offsets (0–20 km) the high-frequency source is able to resolve some more details than the low-frequency source, as far as the shallow to intermediate sedimentary levels are concerned. This is mainly caused by the fact that the high-frequency source has a much sharper primary pulse and reduced bubble pulse compared to the low-frequency source. The data quality can be significantly enhanced by use of band-pass filtering, trace mixing, FK (velocity) filtering, minimum phase predictive deconvolution, as well as Radon filtering. Inspection of particle diagrams documents S-wave splitting, interpreted as microcracks aligned vertically in the sedimentary section by the present day (slightly compressive) stress-field.