Multi-channel Analysis of Surface Waves (MASW)

About Multi-channel Analysis of Surface Waves (MASW)

Multi-channel analysis of surface waves (MASW) is a seismic technique used to investigate the shallow subsurface. The method calculates the shear wave velocity profile of the subsurface through the recording of propagating surface waves and dispersion analysis.

Surface waves has been used for decades to determine the shear wave velocity profile of the subsurface. In the 1980s, researchers developed the MASW technique, which uses a linear array of geophones to measure surface waves. This technique has since become a standard geophysical method for investigating the shallow subsurface.

The surface waves survey method is a non-disruptive, cost-effective way to investigate the shallow subsurface. The technique can be used to map the shear wave velocity and determine the depth to bedrock. Shear wave velocities measured with MASW can be then used to estimate the strength and stiffness of soils and rocks through the calculation of the maximum shear modulus.

The surface waves method is often used in conjunction with other geophysical methods, such as seismic refraction and/or electrical resistivity tomography, to obtain a more complete picture of the shallow subsurface.

To learn more about surface wave surveys or to get a quote, please don't hesitate to get in touch.

Performing MASW Surveys

An array of geophones is used to record propagating surface waves. These can be generated using either an active or passive source. Active source examples include impact hammers and vehicle-mounted weight drops. Passive sources include ambient noise, such as traffic or construction activities.

A shear wave velocity model can be generated from the calculated dispersion spectra of the recorded seismic surface waves. This model can then be used to determine the maximum shear modulus/ground stiffness of the subsurface materials.

Applications of MASW

Surface wave surveys are a versatile tool that can be used for a variety of applications. Some common applications include:

Mapping of voids and/or characterisation of poorly consolidated ground.
Determination of the depth to bedrock
Investigating geologic structures, and landslide assessment.
Monitoring changes in the subsurface, such as settlement or differential compaction
Assessing site conditions for construction projects
Production of seismic velocity profiles of the subsurface.

Benefits of MASW

There are many benefits to using the MASW method, including:

Non-destructive - The MASW method is a non-destructive investigation technique. It does not require drilling or trenching.

Cost-effective - Depending on the survey design, the MASW method is typically more cost-effective than intrusive survey techniques.

Versatile - The MASW method can be used for a variety of applications, from mapping the depth to bedrock to assessing site conditions for construction projects.

Efficient - The MASW method is a relatively quick investigation technique, depending on the requirement.

MASW FAQs

What is shear wave velocity?

Shear wave velocity is a measure of the elastic properties of a material. It can be used to determine the shear modulus of the subsurface materials.

What is dispersion?

Dispersion is the characteristic by which waves of different frequencies travel at different speeds.

How do you calculate the shear-wave velocity of soil?

The shear-wave velocity of soil can be determined from the dispersion spectra of the recorded seismic waves. Through the analysis of different groupings of geophones a series of 1D velocity profiles can be calculated. These are then merged together and inverted to give a continuous cross-section to determine the shear-wave velocity model of the subsurface.

What is a Rayleigh wave?

A Rayleigh wave is a type of surface wave that travels along the surface of a medium. It is characterised by a longitudinal component and a transverse component.

Rayleigh waves are generated by a disturbance at the surface of a medium, such as an earthquake. The waves travel outwards from the point of disturbance and can be recorded by seismometers.

How much does a MASW survey cost?

The cost of an MASW survey varies depending on the size and complexity of the project.

How long does an MASW survey take?

An MASW survey can take anywhere from a few hours to several days, depending on the size and complexity of the project.

Get in touch

If you're interested in our MASW survey services, please don't hesitate to get in touch. We would be more than happy to discuss your specific requirements and provide a quote.

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