Whixall Moss, Shropshire, United Kingdom
Case study
University of Oxford and Harper Adams University
Whixall Moss, Shropshire, United Kingdom
Saturated peat bog
20 meters
Peatlands are a major reservoir for soil carbon. Under changing land-use conditions, the size of this reservoir may change appreciably. However, rapid assessment of peat volume is challenging with traditional methods.
This study demonstrates that seismic refraction and surface wave analysis represent a rapid non-destructive method for peat volume assessment.
2D
14, deployed within 20 minutes
Sledgehammer and plate
2m between receivers on the 2D line
2D plus 4 nodes deployed cross-line
The deployment area was highly challenging, with detailed guidance required to safely traverse the peat field to the deployment location, and deployment into very soft ground and dense tussocky vegetation.
Site access required liaison with Natural England.
1 hr window to complete the deployment once at the site.
The use of STRYDE Nodes™ was essential to this deployment; the nature of traversing the peat-cuttings would have made carrying heavier traditional nodes or cabled geophones hazardous, as well as taking much longer to deploy.
Whilst this was a small deployment, part of the study was proving it could be done extremely quickly to act as a proof-of-concept for larger scale up.
Postdoc, University of Oxford
STRYDE provided seismic acquisition equipment (20 seismic sensors, fully charged and prepared for node deployment) and a data harvesting service. The ready-prepared STRYDE Nodes™ were sent to the client and after data acquisition was completed were returned to STRYDE’s to undergo data download. Continuous seismic records in SEG-D format were created and delivered via the cloud to the client for data processing and interpretation.
The small size and light weight of the STRYDE Node™ meant the deployment of multiple sensors in challenging terrain was feasible within a short timescale. It would have been extremely difficult to perform this survey within the available time window had the team used traditional seismic equipment due to the difficulty of carrying heavier and bulkier systems over the difficult peat bog terrain.
This project achieved much higher resolution data than previous cabled or nodal deployments performed by the University. Initially, a cabled system was considered, however deployment and operation of a cabled system would have been extremely challenging in the peat bog and within the time constraints. The experiment delivered good data quality for the peatland setting. The form factor of the STRYDE Nodes™ resulted in good coupling in the peat when compared to a geophone with a spike.
Rapid delivery of the nodes combined with minimal training requirements meant that it was quick, low-cost and low effort to switch to the STRYDE system, and meant the project started on time. Delivery of processing-ready data was returned to the Universities within two weeks of survey completion.
It was found that both seismic refraction and surface wave propagation appear sensitive to peat depth. Multiple surface wave overtones have been observed, with a high-frequency asymptotic wavespeed of the fundamental mode Rayleigh wave approaching the amazingly low value of 17 m/s.
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