Multichannel Analysis of Surface Wave (MASW) uses seismic surface waves to interpret shear wave velocity profiles. This is done by introducing a seismic impact to be measured by evenly spaced geophones. Individual MASW tests can be regarded as pseudo boring logs. Compiling a series of evenly-spaced, 1-D tests can be used to generate a linear survey alignment to create a 2-D shear wave velocity cross section that can be related to a subsurface profile.
Proposed pipeline alignments are often adjacent to existing pipelines. This limits bedrock investigation tools to geophysical methods that are not impacted by existing pipelines. MASW is an ideal application for bedrock characterization near or even above a pipeline and other underground utilities.
When presented in a cross section, MASW data can provide depth to bedrock along an alignment in addition to other subsurface features. These features can include karst features, other voided features, soil and rock integrity, and the presence of faults. The MASW data, in the cross section presented below, displays subsurface material that varied with depth along a proposed alignment. Indications of karst and weak rock integrity are exhibited throughout the profile and present areas needed for further geotechnical investigations.
THG has been able to streamline this MASW method by attaching a seismic source to an UTV and pulling along a string of geophones. This allows for optimal survey deployment and acquisition along a proposed alignment. For more information, please Contact Us.