Quantifying Seismic Velocity Errors in the Marine Critical Zone from Multichannel Reflection Data

The marine critical zone presents a complicated challenge, requiring reliable imaging of the subsurface at sub-metre-scales in a range of survey conditions, while its dynamic nature adds further complexity. Sediment accumulation/erosion can create resolvable/important bed level changes over a single tidal cycle, while shallow sub-surface conditions respond to the changing sediment/tidal load, leading to both short-and long-period evolutions in subsurface conditions.

Quantifying these evolving conditions is of particular interest for a range of applications, including hydrogeological and geohazard processes. The increasing use of ultra-high-frequency multi-channel seismic data has greatly increased our imaging capability, including implementing methods such as Full Waveform Inversion (FWI). However, these techniques are implicitly dependent on the data acquisition and processing such that the propagation of uncertainties from various sources can manifest as erroneous property characterisation. These in turn can lead to incorrect interpretations during engineering applications or hazard assessments.

We look at developing a workflow to aid in quantifying the errors in seismic velocity. In Particular, we investigate the impact of acquisition geometry and kinematic-based migration velocity analysis for qualitative and quantitative interpretations. We present results from case studies, demonstrating the effectiveness of this method to appropriately quantify errors associated with velocity analysis in the critical zone.