Multicomponent seismic exploration and ground-penetrating radar surveying in the Canadian Arctic

Carlos E. Nieto

This thesis explores the near-surface and deeper subsurface in two different locations of the Canadian Arctic: Devon Island, and Hadween Island in the Mackenzie Delta. A perennial frozen layer, known as permafrost covers part of the study area. The top of this layer thaws during the summer months forming the seasonally unfrozen layer. A similar phenomenon is also observed in the planet Mars. Imaging the subsurface using multicomponent seismic exploration and ground-penetrating radar surveys is the main objective of this work.

The Devon Island case study shows that both methods produce a good quality image of the near-surface. However, the ground-penetrating radar method yields a better image in a faster acquisition and data processing time. A new seismic processing flow based on a linear-offset correction of head wave energy is presented as a solution to produce images under these conditions. A Vp/Vs ratio of 1.55 was obtained for the seasonally unfrozen layer. Velocities of 260 m/s and 168 m/s for P and S-waves were obtained as well. The permafrost shows a similar Vp/Vs ratio of 1.53, with P and S-wave velocities of 3100 and 2030 m/s respectively. For the 2.5D ground-penetrating radar surveys linear interpolation was required to produce an image from the subsurface. A radar velocity change was interpreted as the contrast between lithology of thawed layer and permafrost.

In the Mackenzie Delta study area, the first known multicomponent survey in the Canadian Arctic was recorded and processed. PP and PS seismic sections were obtained and interpreted using well log data from the Hansen G-07. A compelling correlation between the PP and PS seismic sections was found using a Vp/Vs ratio of 1.9.