MID-TERM STUDY QUESTIONS FOR GEOL581

Define

• wavelength of a wave
• frequency of a wave
• period of a wave
• amplitude of a wave

Give a formula which relates wavelength and frequency.

Distinguish between a seismograph and a seismogram.

Explain in very simple terms how a seismograph works.

What are the 4 principle types of waves produced by an earthquake?
Which of these are body waves?
Which are surface waves?

Which waves are the fastest? Gives equations for the velocities of P-waves and S-waves.

What is the most important factor in determining velocity in rocks?

What are SV and SH waves?

Why can't S-waves travel through liquid (give a mathematical proof)?

Show mathematically why P-waves are faster than S-waves.

Describe the motion of a particle of rock as each of the four principle seismic waves passes.

What is the effect of depth of focus on the production of surface waves?

What happens when a seismic wave meets a surface of discontinuity within the Earth?

What is the relation between the angle of reflection and the angle of incidence?

Give Snell's Law.

What happens to a wave when it meets a surface of discontinuity at the critical angle?

Be able to trace the paths of earthquake waves such as PS, PcS, PKP, PKIKP, pPcP, etc.

List some reflected and/or refracted waves which might be mistaken on seismograms for surface waves and for aftershocks.

Explain how the epicenter of an earthquake can be located.

How do we know that the upper mantle is partially molten?

At what depths do major discontinuities exist within the Earth? What are the names of these discontinuities?
Name 2 minor discontinuities in the Earth.

What are the two methods commonly used in seismic prospecting?
Which is most often used? Which gives the most information?

What sources of energy are most often used in seismic exploration?

Describe in detail how refraction profiles would be produced, and what information could be obtained from them.

What kind of time/distance graph would be produced where velocity increases continuously with depth?

What kind of graph would be produced where velocity first increases continuously with depth and then abruptly changes?

What kind of graph would be obtained if a seismic profile was taken perpendicular to the strike of a vertical fault?
How can the throw of the fault be determined?

List 3 factors which help determine seismic wave velocity.

How does one recognize a reflecting horizon on seismograms?

How can the depth to a reflecting horizon be determined?

How can the dip of a reflecting horizon be determined?

What is seismic/earthquake tomography? What information can it provide?

List and discuss possible geophysical properties which may be indicators of forthcoming earthquakes.

Hooke's Law.

• Define
• stress
• strain
• Young's modulus
• Poisson's ratio
• bulk modulus
• compressibility
• modulus of rigidity
• shear modulus

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updated October 30-2004