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Introduction to Geophysics
Ali O. [email protected].
saDepartment of Earth SciencesKFUPM
Lecture 1Overview
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Dr. Ali O. Oncel: Building 26, Room:319
Saturday : 8:00-9:00 PM room 319
Monday : 8:00-9:00 PM room 319
Wednesday : 8:00-9:00 PM room 319
Any time you can ask me an appointment through e-mail.
Scheduled Office HoursIn
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Parasnis, Pprinciples of Applied Geophysics 5E, 1997
R.J. Lillie, Whole Earth Geophysics, Prentice Hall, 1999.
Recommended Text and GradingIn
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GEOP 204: %
Final Exam 35
Comprehensive Exam 30
Quiz 15 Homework 15
Class Participation on time 5
Monday is day for weekly exam.
Wednesday is day for field-trip or work.
Homework is due one week after it is assigned
Late homework will not be accepted one week after the deadline.
Late homework will be penalized:
HomeworkIn
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80% for 1 day late
60% for 2 day late
40% for 3 day late
20 % for 4 day late
10% for 5 day late.
Scope of Course
Providing knowledge more about the mathematical and physical aspects of Applied and solid Earth geophysics such as the currently accepted physical models used to describe the Earth's interior and evolution…………………………..Providing knowledge about the most important datasets and methods which have been used to learn about Applied and Solid Earth Geophysics………………...
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Geology + Physics
Geophysics
Geophysics aims to interpret the subsurface by combining observations of the Earth Materials (geology) with observations of physical phenomena (physics).
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Forward Modeling (1)
what the cause of our observations?
By adjusting the model parameters, we try to find the best model that fit the predictions with observations.
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Refraction Reflection
Seismic refraction• Used to study large scale crustal layering: thickness and velocitySeismic reflection• “Imaging” of subsurface reflectors• Difficult to determine accurate velocities and depths
Applied Seismology In
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Inversion (2) In
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InterpretationsAs for the interpretations of geophysical data, I just want emphasize that most interpretations are actually “non-unique”. That means more than one interpretation can explain the data. The problem is like that of the “blind men and the elephant;” Thus, all the available information must be synthesized in order to obtain a better picture of the subsurface structure.
It is wise to use the words like “uncertain, possibly, unclear suggestions…” when you describe your interpretations. However in the real literature, you may see that a lot of authors still use the words like “certain, undoubtedly, positive proof, strongly suggested…”
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Seismic refraction profile recorded in ocean basin, Sheriff and Geldart, 1995
S – Reflections from bottom of water
Refraction Interpretation
DD - Direct Arrival
P
P - Lower Crustal Refraction within thecrust and from the Moho
S
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Fowler, 1990
Seismic Refraction
Interpretation
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Reflection Interpretation
Transform Fault
Basement
Bowen and White, 1986
A migrated seismic-reflection profile across the Vema Transform Fault on the Mid-Atlantic Ridge at 6°N, approximately midway between the African and South American plates.
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