Note Outline: Refraction Seismic Methods

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Introduction

• Seismic Methods: Refraction and Reflection
• Advantages and Disadvantages of Seismic Methods Versus Other Methods Studied
• Advantages and Disadvantages of Refraction and Reflection Methods
• Elastic Waves
• Types of Seismic Waves
• Wave Propagation: Wavefronts and Raypaths

Seismology and Geology

• Wave Interaction with Boundaries
• Snell's Law
• Velocities and Rock Properties
• Seismic Velocities of Common Earth Materials

Refraction Basics

• Another Simple Earth Model: Low-Velocity Layer Over a Halfspace
• Head Waves
• Records of Ground Motion
• Travel-time Curves for a Simple Earth Model
• First Arrivals
• Determining Earth Structure from Travel Times
• Derivation of Travel Time Equations
• High-Velocity Layer Over a Halfspace: Reprise

Refraction Seismic Equipment and Field Procedures

• Equipment Overview
• Types of Seismic Sources
• Seismometers or Geophones
• Recording Ground Displacement at Several Offsets Simultaneously
• Recording Systems
• Sources of Noise

Interpretation of Seismic Observations

• Picking Times of Arrivals
• Wave Propagation with Multiple Horizontal Layers
• Travel Time Curves from Multiple Horizontal Layers
• Hidden Layers
• Head Waves from a Dipping Layer: Shooting Down Dip
• Head Waves from a Dipping Layer: Shooting Up Dip
• A Field Procedure for Recognizing Dipping Beds
• Estimating Dips and Depths from Travel Time Observations