Unit 4 GPS infinitesimal strain analysis presentation
- 1. Using Velocities from a Triangle of GPS Sites to Investigate Crustal Strain UNAVCO GPS Crustal Strain Curriculum Team September 9, 2012
- 3. September 9, 2012 Locate three non-colinear GPS sites
- 4. September 9, 2012 E-W and N-S components of sites’ velocities
- 5. September 9, 2012 E-W + N-S components = total site velocity
- 6. September 9, 2012 Total site velocities
- 7. September 9, 2012 Define the triangle between the GPS sites
- 8. September 9, 2012 Define the centroid of the triangle
- 9. September 9, 2012 Transform coordinate system to a new origin at the centroid of the triangle
- 10. September 9, 2012 Inscribe a circle in the center of the undeformed triangle
- 11. September 9, 2012 The average of the three total site velocities is the translation vector
- 12. September 9, 2012 The triangle deforms as it moves. The vector from the centroid of the undeformed triangle to the centroid of the deformed triangle is the same as the translation vector.
- 13. September 9, 2012 Subtracting the translation vector from the site velocities brings the two triangle centroids together.
- 14. September 9, 2012 Subtracting the translation vector from the site velocities brings the two triangle centroids together.
- 15. September 9, 2012 The total site velocities minus the translation vector yields the site vectors associated with the change in shape of the triangle.
- 16. September 9, 2012 The red line is the major axis of the strain ellipse, and the blue line is the minor axis
- 17. September 9, 2012 The ellipse axes remain perpendicular to each other when the strain is reversed.
- 19. September 9, 2012 The rotational component of strain is indicated by the angular change in the orientation of the red lines.