Because of an increased ability to discriminate useful signal from harmful noise, the MASW method assures an increased resolution when extracting signal in the midst of
noise that can be anything from natural or cultural activities (wind, thunder, traffic, etc.) to other types of inherent seismic waves generated simultaneously (higher-mode
surface waves, body waves, bounced waves, etc.) (Fig. 3). In consequence, overall field procedure for data acquisition and subsequent data-processing step become highly
effective and tolerant, rendering a non-expert method. The multichannel seismic concept is analogous to resolution in digital imaging technology (Fig. 4). As the higher
number of bits available, a broader color resolution is achieved, whereas the higher image resolution is achieved as more pixels are used to capture the image. The concept
of number of channels plays similar roles to those by the bit and pixel concepts in delineating the subsurface information.
noise that can be anything from natural or cultural activities (wind, thunder, traffic, etc.) to other types of inherent seismic waves generated simultaneously (higher-mode
surface waves, body waves, bounced waves, etc.) (Fig. 3). In consequence, overall field procedure for data acquisition and subsequent data-processing step become highly
effective and tolerant, rendering a non-expert method. The multichannel seismic concept is analogous to resolution in digital imaging technology (Fig. 4). As the higher
number of bits available, a broader color resolution is achieved, whereas the higher image resolution is achieved as more pixels are used to capture the image. The concept
of number of channels plays similar roles to those by the bit and pixel concepts in delineating the subsurface information.
Advantages of the MASW Method
Unlike the shear-wave survey method that tries to measure directly shear-wave velocities—which is notoriously difficult because of difficulties in maintaining favorable signal-
to-noise ratio (S/N) during both data acquisition and processing stages—MASW is one of the easiest seismic methods that provides highly favorable and competent results.
Data acquisition is significantly more tolerant in parameter selection than any other seismic methods because of the highest signal-to-noise ratio (S/N) easily achieved. This
most favorable S/N is due to the fact that seismic surface waves are the strongest seismic waves generated that can travel much longer distance than body waves without
suffering from noise contamination (Fig. 1).
Unlike the shear-wave survey method that tries to measure directly shear-wave velocities—which is notoriously difficult because of difficulties in maintaining favorable signal-
to-noise ratio (S/N) during both data acquisition and processing stages—MASW is one of the easiest seismic methods that provides highly favorable and competent results.
Data acquisition is significantly more tolerant in parameter selection than any other seismic methods because of the highest signal-to-noise ratio (S/N) easily achieved. This
most favorable S/N is due to the fact that seismic surface waves are the strongest seismic waves generated that can travel much longer distance than body waves without
suffering from noise contamination (Fig. 1).
In comparison to a conventional drilling approach, it is fully implemented on the
ground surface (non-invasive), covers the subsurface continuously in a manner
similar to ground-penetrating radar (GPR), and provides more complete
coverage (Fig. 2).
ground surface (non-invasive), covers the subsurface continuously in a manner
similar to ground-penetrating radar (GPR), and provides more complete
coverage (Fig. 2).
Fig. 1. Earthquake recording around the earth showing
strong surface waves.
strong surface waves.
Fig. 2. Comparison of seismic survey and conventional drilling.
(Upper) Fig. 3. Illustration showing an MASW field survey and an actual
field record showing various types of seismic waves can be distinguished.
(Right) Fig. 4. An analogy of the seismic multichannel approach to digital
imaging concepts of number of bits and pixels.
field record showing various types of seismic waves can be distinguished.
(Right) Fig. 4. An analogy of the seismic multichannel approach to digital
imaging concepts of number of bits and pixels.
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