Week 1: Introduction 13-15
February
- Recommended Text and
Grading
Lecture
1
top
Introduction to Geophysics
What is Geophysics?
-
Solid Earth Geophysics
- Exploration Geophysics
Examples of Geophysics
-
Exploration Geophysics
- Engineering Geophysics
- Environmental Geophysics
- Groundwater Geophysics
- Archaeo – Geophysics
- Forensics
Applications
Examples of Geophysical
Methods
Gravity
Magnetics
Seismics
Ground Penetrating Radar
Resistivity
Geophysical Noise
-
Data Processing
-
Visualizing Geophysical
Data
Steps in Geophysics
- Identify Geologic Problem
- Survey Plan
- Data Acquisition
- Data Reduction
- Data Analysis
- Modeling
- Write Report
Introduction to Seismic
Waves
Waves in a Pound
Sound Wave Analogy
What is Wave?
Wave Terminology
Wavelength and Period
Wave Speeds
Sources of Seismic Waves
Multiple Frequency Signals
What is Elastic Behavior?-
Elasticity of
Minerals
- Ductile Deformation
- Brittle Deformation
- Ductile/Brittle Behavior through the
Lithosphere and Asthenosphere
- Elastic Constants
- Bulk Modules
- Shear Modules
- Poisson Ratio
- Typical Values of Elastic Constants for
Selected Materials
Body Waves
Surface Waves
Exploration
Seismology: Fundamentals
- Elastic Coefficients and Seismic Waves
- Birc's Law
- Nafe-Drake Curve
- Factors affecting P-wave and S-wave velocity
- Seismic velocities for Geological Materials
- Amplitude Changes of Particle Motions
- Wavefronts and Ray Paths
- Seismic Trace
- Seismic Wave Types
- Huygens's Principle
- Fermat's Principle
- Travel-time Graph
- Estimates of Seismic Velocity
- Reflected/Refracted waves
- Model Calculation for simple, horizontal, two layers
- Ray Paths
- Snell's law-Critically Refracted Arrival
- Seismic Refraction
- Behavior of refracted ray on velocity changes
Lecture 2
Lecture
3
Lecture 4
Lecture
5
Lecture
6
- Quiz
top
Week 4-5:
6-8-13-15, March
Earthquake
Seismology: Fundamentals
- Earthquake Waves: As Probes of Earth's Interior
- Travel Time Models of Earthquakes for flat earth
- Travel Time Models of Earthquakes for Curved earth
- Seismic Waves Through the Earth
- How do we know what’s inside the Earth?
Field Work
Lecture 7
Lecture
8
Lecture
9
Lecture 10
Lecture 11
top
:
6-8-13-15, March
Refraction Interpretation
-
Interpretation Models
- Refraction Seismology Objective
- Single Horizontal Interface
- Several Horizontal Interfaces
- Generalized Refraction Model
- Refraction: Example from Ocean Basin
- Refraction from Oceanic Crust
- Formation of Oceanic Crust
Thin Layer Effect/Dipping
Layer Refractions
-
- Problem Situations
- Low Velocity layer (V2<V1<V3)
- Thin layer (V3>V2>V1 but h2 very small)
- Velocity Inversion-Hidden Layers
- Single Dipping Refractor Surface
Tectonic Interpretation of Seismic
Refraction Profiles
- Map of P-wave Velocity (km/s)
- Map of Crustal Thickness (km)
- Example 1: North American Plate
- Example 2:Europe
- Example 3:Mid-Atlantic Ridge
- Example 4:South American
Margin
- Example 5:Cascadia
Subduction zone
- Example 6:Red Sea
Seismic
Reflection 1: Acquisiton, Processing, and Waveform Analysis
- What Seismic Reflection
Provides?
- What requires for a successful
study of Reflection?
- What provides Seismic Reflection
on subsurface geological Model?
- On Land- Seismic Reflection
- On Sea- Seismic Reflection:
Photos from Seismic Crew
- Equipments: Vibrator Track and
Receiver Truck, Geophones, Battery
- What is a seismic section?
- what is a Seismic Line?
- Nature of Seismic Section?
- Acoustic Impedance
- Enhancement the quality for
Compressional waves?
- Single Channel Seismic
Reflection?
- Angle Incidence=Angle Reflection
- What is a seismic Profile?
Lecture 12
Lecture 13
Lecture 14
Lecture 15
Seismic Refraction
Software
PLOTSEC
RAYGUI
top
Week 8-9:
3-5,17,19 April
Seismic
Reflection 2
- Snell's Law
- Reflection "Presentation"
- Multifold Reflections
- Receiver Arrays
- CMP method
- Processing
- Normal Moveout
Seismic
Reflection 3
- Example: Data Acquisition in Shaybah Field (Alfaraj
et al., 1998, GeoArabia, Vol. 3, No 2)
- Over 120 million seismic traces and over 100,000 shot
points, covering an area of about 1,100 sq km.
Primary Reflection
Multiples
NMO – Normal Moveout Correction
- Velocity Analysis
- Example: Gathers and NMO Corrected CMP
Mute
Static Corrections
Types of Velocities
- Average Velocity
- Root mean Square Velocity (RMS)
- Interval velocity
Seismic
Reflection 3: Acquisition, Processing, and Waveform Analysis
- Example: Disk Formula
- Seismic Waveform: Input Seismic Signal
- Homogenous Medium
- Strong Interface
Amplitude
- Minimum Phase Pulse
- Zero Phase Pulse
Acoustic Impedance
Coefficients of Reflection and Transmission
- Example 1: Air-water reflection
- Example 2: Water-Air Reflection
Reflection from Single Interface
Reflections from Several Interfaces
Lecture 16
Lecture 17
Lecture 18
Lecture 19
Lecture
20
Problem Sets
Field Trip: KFUPM Beach, April 26,
Afternoon, 12.30 PM-18.00 PM
SIP
Program Download the program in directory
named "SIP"
Field Data , do not
forget to select 2 for instrument ES-1225
Smartseis seismograph
we used in the field:
Smartseis manual,
quick sheet,
Geometrics
top
Gravity 1
April 29, May 1, 6,8,10,13,
- Earth's Gravity Potential Field
- Earth's Magnetic Potential Field
- Differences in Earth's Potential Fields
- Earth's Gravity Field
- Earth's Gravitational Acceleration
- Theoretical Gravity
- Free Air Gravity Correction
- Gravity Anomaly
- Free Air Gravity Anomaly
- Bouguer Correction
- Bouguer Gravity Anomaly on Land
- Bouguer Gravity Anomaly on Sea
- Summary of Equations for Free Air and Bouguer Gravity
Anomalies
- Terrain Correction
Gravity Measurement
- Absolute Gravity
- Relative Gravity
- Measurement of relative gravity
- Free Fall Methods
- Gravity Units
- Example 1: Mars's twin moons
- Example 2: The Valley and Ridge Province (1-5 mgals)
- Sensitivity: Density Distribution
- Sensitive to changes in Mass (Density) changes
- Densities of Geological Materials
On-Line
Gravity Map Construction Tool
Gravity and Isostasy
- Isostatic Equilibrium
- Topography of ocean floor
- Two forms of isostatic uplift
- Sign of Bouguer Anomaly in Ocean (+) and Continent (-)
- Examples from Saudi Arabia
Lecture
21
Lecture
22
Lecture
23
Lecture
24
Lecture
25
top
Gravity 2
May 15,17
- Gravity and Isostasy
(Cont)
- Local Isostasy
- Mathematical Background of Airy Model
- Mathematical Background o
f Pratt Model
Local Isostasy &
Flexure
Regional Isostasy & Flexure
Flexural Rigidity (D)
Flexural Modeling
Examples of Lithospheric Flexure
- Example from the West Africa (Watts and
Stewart, 1998).
Lecture
26
Lecture
27
top
Gravitational effect of a buried sphere
- Size Effect
- Gravity Contrast
- Depth Effect
Regional Gravity due to dipping plane
Sources of the Local and Regional Gravity
Anomalies
Wavelength Changes of Anomaly regarding the
burial depth of material
Factors effecting the Gravity Anomalies
- Density Contrast
- Depth to anomaly Source
- Geometry
Gravity Effect of Sphere
Depth Estimates
Examples for the regional Bouguer
Anomalies
Ambiguity in Gravity Interpretation
Gravity variation due to infinite
slab
Gravity variation due to
Semi-Infinite slab
Estimating Δgz for an infinite slab
Δgz versus Slab’s position
Gravity for Semi-Infinite Slab
Lecture
28
Lecture
29
Lecture
30
top
