Geophysics in Sedimentology

This workshop will focus on the use of geophysical techniques to aid in understanding sedimentary structures in the subsurface. It will consist of two parts: (1) the use of Ground Penetrating Radar (GPR) to understand sediments in the shallow subsurface, and 2) will discuss the construction and use of synthetic seismic models of subsurface sedimentary sequences to enable an improved understand of seismic imaging and aid interpretation of real seismic sections.

  1. GPR is used extensively in engineering, archaeology and glaciology, and is a cost-effective method to aid the interpretation of near-surface sedimentary sequences, where borehole and outcrop control is scarce. However, GPR has its limitations and, to achieve the best results, certain conditions need to be met. This section of the workshop will i) introduce  GPR method from an end-user point of view (no advanced geophysical knowledge required!), ii) discuss best practices and limitations of GPR , iii) demonstrate the data acquisition process in the field using two types of GPR antennae, and iv) demonstrate a processing and interpretation workflow.   This workshop will include an element of field demonstration (weather permitting) during which participants will be able to get hands-on experience with the tool.
  2. Seismic modelling is a tool that primarily aims at improving interpretation and increasing knowledge of subsurface complexities. The ability to see how geological features and seismic data are related is a powerful tool for understanding the subsurface.  In addition the ability to change parameters, such as frequency and choice of wavelet, allows for extensive experimentation and sensitivity testing.  The most common method of seismic modelling follows a 1D approach where multiple 1D traces are convolved with a wavelet to produce synthetic seismic.  This results in the generation of seismic that only reproduces the input geometry. To address the weaknesses associated with 1D seismic modelling, a 2D/3D Point Spread Function (PSF) based approach is now recommended as it generates complex and realistic synthetic seismic images. This approach bypasses the computationally expensive full wavefield methods, so can be done quickly and produces results comparable to real seismic datasets.  This workshop will introduce the theory and purpose of seismic modelling before introducing participants to 1D and 2D/3D PSF-based seismic modelling. Participants are likely to be invited to create their own geological sections before converting their sections into synthetic seismic. The differences between the two options will be addressed, the variability of parameters will be investigated, and direct comparisons between synthetic seismic and real seismic will be discussed.