Time-Migrated Multichannel Seismic Profiles of the Gulf of Cagliari (CG Dataset) for Plio-Quaternary Neotectonic Analysis in Southern Sardinia (Italy)
Description
This dataset is the result of a scientific collaboration between Istituto Nazionale di Oceanografia e di Geofisica Sperimentale - OGS and the Universities of Trieste and Cagliari in the framework of the WS10 project, funded by OGS (Grant OGS-CdA, no. 4.2.5.2010), with the support of the then Ministry of Education, Universities, and Research (MIUR) in 2010. The CG seismic dataset described here supports the analyses presented in: Del Ben A., Fais S., Geletti R., Caradonna M.C., Frisicchio V., Brancatelli G., 2026. "Tectonic Interplay in the Gulf of Cagliari (Italy): Extension, Compression and Strike-Slip Movements". Basin Research, 38, no. 3, May–June 2026: e70115. https://doi.org/10.1111/bre.70115 The CG profiles comprise five multi-channel seismic reflection lines acquired by the research vessel N/R OGS Explora in September 2010 (Zgur F., Geletti R., et al., 2011: https://hdl.handle.net/20.500.14083/6738). The resolution and penetration depth of these lines depend primarily on the characteristics of the source. The acquisition settings, including source and streamer depths, resulted in a notch frequency of 150 Hz. Assuming an average seismic velocity of 2000 m/s, the theoretical vertical resolution within the PQ sequence cannot be finer than 3–4 metres. The resolution remains high throughout the PQ sequence, while the seismic signal within the Oligo-Miocene sequence progressively attenuates. The seismic data are provided in SEG-Y format, with coordinates projected in UTM Zone 32 stored in header fields 73 and 77.
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The sequence of the multichannel seismic (MCS) data processing, from raw records to final products suitable for interpretation, has evolved significantly over time. The primary objective of seismic processing is to transform raw data into a form that optimises the extraction of geological information during interpretation. Generally, the three main operations in a processing workflow are deconvolution, stacking, and migration (Yilmaz, 2001). Deconvolution improves temporal resolution, stacking attenuates uncorrelated noise and increases the signal-to-noise ratio (S/N), and migration collapses diffractions and relocates dipping events to their true subsurface positions. In marine seismic data, multiple attenuation is a critical processing step. This is particularly relevant for the CG line, where multiple reflections obscure primary signals within the Plio–Quaternary sequence. To mitigate this effect, several processing techniques were applied. Various multiple attenuation methods were applied, including Surface-Related Multiple Elimination (SRME) (Verschuur DJ, Berkhout AJ, Wapenaar CPA, 1992. Adaptive surface-related multiple elimination. Geophysics, 57(9): 1166–1177), Wave Equation Multiple Attenuation (WEMA) (Berkhout AJ, Verschuur DJ, 1997. Estimation of multiple scattering by iterative inversion, Part I: Theoretical considerations. Geophysics, 62(5), 1586–1595), and predictive deconvolution (Yilmaz, 2001). An initial velocity analysis was performed, and the resulting velocity model was used for pre-stack time migration (PSTM). The quality of the migration was assessed by analysing common depth point (CDP) gathers, where correctly migrated events appear as flat reflections. Migration and velocity analysis were repeated iteratively, refining the velocity model at each step until a satisfactory result was obtained to support further analysis and interpretation. The MCS data were processed using Aspen Technology® Echos and Geodepth software at the SEISLAB laboratory of OGS, with workflows including SRME/WEMA multiple attenuation and pre-stack time migration (PSTM). The authors acknowledge academic grants from Aspen Technology for Echos and Geodepth software.
Institutions
- National Institute of Oceanography and Applied GeophysicsFriuli Venezia Giulia, Trieste
- University of TriesteFriuli Venezia Giulia, Trieste