The short course will include presentations on passive surface wave theory, data acquisition, data processing, and applications.
Passive surface wave methods using ambient noise are increasingly being used for geotechnical, environmental, and earthquake engineering applications. Conventional microtremor array measurements using up to 12 receivers in two-dimensional arrays have been widely used for decades to supplement active surface wave methods and provide 1D S-wave velocity (Vs) to depths of several hundred meters. A new passive surface wave method has been developed that delineates 2D or 3D near-surface Vs structure from ambient noise obtained from dozens of receivers on the ground surface. The recent development of cableless (nodal) seismic systems enables such large-scale data acquisition. The short course will include discussion of passive surface wave theory and data acquisition and processing methods. Numerical and field examples will be presented to demonstrate how this method can be used to quickly estimate Vs structure over a range of depths, with applications to geotechnical, environmental, and earthquake engineering.
Prerequisites (Knowledge/Experience/Education Required)
Basic knowledge and experience with near-surface seismic methods (refraction, MASW) and relevant mathematics (knowledge of the Fourier transform, complex numbers, and linear algebra are ideal).
Detailed Course Description
The short course will include presentations on passive surface wave theory, data acquisition, data processing, and applications. The theory will introduce the fundamental idea of ambient noise, the Fourier transform, phase velocity, the wave equation, and inversion. The mathematics will be described with simple numerical examples and course attendees will be able to follow the calculations using Excel or MATLAB. The theory will particularly focus on the Spatial Autocorrelation (SPAC) method of processing ambient noise obtained from spatially un-aliased receiver arrays. Small-scale data acquisition using 10 to 15 receivers in a 2D array (microtremor array measurements-MAM) will be performed. Industry-standard software will be used for data processing. Many examples of passive surface wave methods applied to geotechnical, environmental, and earthquake engineering will also be introduced.
Attendees will have the following abilities after completing the course:
- Distinguish between active and passive surface waves, deterministic and temporal wave versus random-stochastic and continuous wave fields, and P- and S-wave velocity and phase velocity.
- Choose from investigation methods and determine the suitable approach, e.g., refraction or surface wave methods, active and/or passive methods.
- Design surveys, including the geometry with parameters such as array size, number of receivers etc.
- Acquire passive surface wave data using an industry-standard seismic system.
- Process passive surface wave data using industry-standard software and understand the results.
- Evaluate passive surface wave case studies, reports, and publications.