1. Multichannel Analysis of Surface Waves (MASW)
Short Course
October, 2000

2. Instructor Education Expertise 1984, Seoul National University (B.S.)
1988, Ohio University (M.S.)
1995, The University of Kansas (Ph.D.)
Expertise
Seismic Technique Development for Near-Surface Application
Swept Impact Seismic Technique (SIST)
MASW
Software Development
WinSeis
SurfSeis

3. Short Course (Schedule)
Introduction to MASW (Friday, 10/13)
Field Survey I (Saturday, 10/14)
Field Survey II (Monday, 10/16)
Use of “SurfSeis” (Tuesday, 10/17)

4. Introduction to MASW CONTENTS
Geophysical Methods for Near-Surface Investigation
Surface-Wave Method
SASW and MASW
Higher Modes (Overtones)
Overall Procedure of MASW
Case Studies with MASW

5. Geophysical Methods for Near-Surface Investigation
Seismic
Resistivity
Electromagnetic (EM)
Ground Penetrating Radar (GPR)
Potential Field (e.g., Gravity Survey)

6. Seismic Methods Refraction Method Reflection Method
Surface-Wave Method
Joint (Refraction+Surface Wave) Method

7. Seismic Method (Refraction)
Most Widely Used Method for Engineering Applications
Reconnaissance Method
(I.e., inappropriate as Exploration Method)
Problem with Velocity Reversal
Tomographic Approach-Most Advanced

8. Seismic Method (Reflection)
High-Resolution Imaging
Most Difficult Method
Weak Signal
Complicated Processing
Limitation with Wavelength
Future - Ultra High Frequency (UHF) Method

9. Seismic Method (Surface Wave)
Simplest and Easiest Method for Engineering Applications
Reconnaissance and Exploration
Both S-Wave and P-Wave Velocity
Widest Application

10. Surface-Wave Method
CONTENTS
Surface Waves
MASW
MASW and SASW

11. Surface Waves Ground Roll Large Amplitude Dispersion Property
Near-Surface

12. Dispersion of Surface Waves
Dispersion Curve

13. Dispersion and Attenuation
Earth Model
Dispersion Curve
Attenuation Curve

14. Multichannel Analysis of Surface Waves (MASW)
Pattern Recognition
Fast Survey
Various Multichannel Processing Methods

15. Higher Modes (Overtones) of Surface Waves
Wave Equation Predicts
Multiple Velocities for One Frequency
Energy and Velocity — changes with Layer Model, Source and Receiver Parameters

16. Layer Model and Higher Modes
Amplitudes

17. River-Bottom Hydrophone Data
Offset and Higher Modes
River-Bottom Hydrophone Data
(Fraser River, B.C.)

18. Dispersion Curves — Fraser River, B.C.

19. Higher Modes — Why Excluded?
Not Significant Energy?
Not Easy to Detect?

20. MASW and SASW Multichannel Analysis of Surface Waves (MASW)
-Pattern Recognition
-Diverse Processing
-P- and S-Wave Velocities
-1-D and 2-D Profiling
Spectral Analysis of Surface Waves (SASW)
-Two Receivers (Q/C Impossible)
-Repeated Measurements (Time
and Labor Intensive)
-Dispersion Curves Speculative
-S-Wave Velocity only
-1-D

21. MASW and SASW MASW SASW Pattern Recognition
Accurate Dispersion Curves
Higher Modes
Offset Dependent Dispersion Curve
Risk of Error
Many Measurements

22. Procedure of MASW (3 Steps)
Acquisition
Dispersion Analysis
Inversion

23. MASW - Applications
1-D S-Wave Profile
2-D S-Wave Map

24. Vp, Vs, and Poisson's Ratio Map
MASW - Applications
2-D & 3-D
Vp, Vs, and Poisson's Ratio Map

25. MASW - Field Procedure Seismic Source Receivers Seismograph
Offsets (Source Offset and Receiver Spacing)
Field Notes

26. MASW - Seismic Source Hammer Near-Surface Material
The Heavier, The Deeper
Strong Source: Low Frequency
Weak Source: High Frequency
Investigation Depth (Z)
Z < 5 m ( < 2 Kg)
Z < 10 m (< 5 Kg)
Z > 10 m (10 Kg)

27. MASW - Seismic Receivers
Low-Frequency Geophones
Near-Surface Material
The Lower Frequency, The Deeper
Investigation Depth (Z)
Z < 5 m ( 4.5 Hz, 10 Hz, 20 Hz)
Z < 10 m (4.5 Hz, 10 Hz)
Z > 10 m (4.5 Hz)

28. MASW - Seismograph Minimum 12 Channel Absolutely No Low-Cut Filter
Low Dynamic Range OK
Preparation of (at least) 24 traces by Walkaway Format
Absolutely No Low-Cut Filter

29. MASW - Offsets Source Offset Receiver Spacing Noise Analysis
Approximately 1/2 Max. Depth of Investigation
Receiver Spacing
The Softer Material, The Narrower
Usual Soil Sites (0.5 m)
Hard Surface (1 m)
Noise Analysis

30. MASW - Field Notes Source Sampling Interval (e.g., 1 ms)
Recording Time (e.g., 1000 ms)
Number of Channels (e.g, 12)
Geophone (e.g., 4.5 Hz)
Field Map
Each Shot
File Name (e.g., 1001.dat)
Location of Source and Receiver (e.g., Station Number)
Source Offset (e.g., 5 m)
Receiver Spacing (e.g., 0.5 m)