Podcast
Questions and Answers
A geologist observes a fault plane intersecting the horizontal, with the fault dipping towards the east. If the angle between the fault trace and the north direction is 70 degrees, what is the azimuth ($\phi$) of the fault?
A geologist observes a fault plane intersecting the horizontal, with the fault dipping towards the east. If the angle between the fault trace and the north direction is 70 degrees, what is the azimuth ($\phi$) of the fault?
- 290 degrees
- 70 degrees (correct)
- 110 degrees
- 250 degrees
A fault has a dip angle ($\delta$) of 45 degrees. How would you best describe the orientation of the fault plane?
A fault has a dip angle ($\delta$) of 45 degrees. How would you best describe the orientation of the fault plane?
- The fault plane has an angle greater than 90 degrees from the horizontal.
- The fault plane is inclined at a moderate angle to the horizontal. (correct)
- The fault plane is horizontal.
- The fault plane is vertical.
During an earthquake, the slip or rake ($\lambda$) on a fault is measured to be -90 degrees. What does this indicate about the relative displacement?
During an earthquake, the slip or rake ($\lambda$) on a fault is measured to be -90 degrees. What does this indicate about the relative displacement?
- The relative displacement is purely horizontal and to the left.
- The relative displacement is purely horizontal and to right.
- The relative displacement is purely vertical, with the hanging wall moving upwards.
- The relative displacement is purely vertical, with the hanging wall moving downwards. (correct)
Consider a fault where the relative displacement ($\Delta u$) varies along the fault plane. In calculating the overall seismic moment, which value of $\Delta u$ is typically used?
Consider a fault where the relative displacement ($\Delta u$) varies along the fault plane. In calculating the overall seismic moment, which value of $\Delta u$ is typically used?
A geologist is analyzing a fault zone to assess earthquake risk. Which parameter provides the MOST direct indication of the size of the rupture area involved in potential seismic events?
A geologist is analyzing a fault zone to assess earthquake risk. Which parameter provides the MOST direct indication of the size of the rupture area involved in potential seismic events?
Flashcards
Azimuth (Φ)
Azimuth (Φ)
The angle between a fault's trace on a horizontal plane and the north direction (0° to 360°).
Dip (δ)
Dip (δ)
The angle between the fault plane and the horizontal plane (0° to 90°).
Slip or Rake (λ)
Slip or Rake (λ)
The angle between the direction of relative displacement and the horizontal on the fault plane (-180° to 180°).
Relative Displacement (Δu)
Relative Displacement (Δu)
Signup and view all the flashcards
Area (S)
Area (S)
Signup and view all the flashcards
Study Notes
Azimuth (𝜙)
- This is the angle between the fault trace, which is the intersection of the fault plane with the horizontal, and the northerly direction.
- The range of values for azimuth is between 0° ≤ 𝜙 ≤ 360°.
- It is measured so that the fault plane dips to the right-hand side.
Dip (𝛿)
- This is the angle between the fault and the horizontal plane.
- The range of values for dip is 0° ≤ 𝛿 ≤ 90°.
Slip or Rake (λ)
- This is the angle between the direction of relative displacement and the horizontal direction.
- The range of values for slip or rake is -180° ≤ λ ≤ 180°.
- It is measured on the fault plane.
Relative Displacement (∆u)
- This is the distance traveled by a point on either side of the fault plane.
- If ∆u varies along the fault plane, its mean value is generally used.
Area (S)
- This represents the surface area of the highly stressed region within the fault plane.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Understanding fault plane geometry involves parameters like azimuth, dip, and slip. Azimuth measures the angle between the fault trace and north. Dip measures between the fault and horizontal plane and slip measures the direction of relative displacement.
