Unit 4 GPS infinitesimal strain analysis presentation
22
Using Velocities from a Triangle of GPS Sites to Investigate Crustal Strain UNAVCO GPS Crustal Strain Curriculum Team September 9, 2012
-
Upload
serc-at-carleton-college -
Category
Documents
-
view
32 -
download
0
Transcript of Unit 4 GPS infinitesimal strain analysis presentation
Using Velocities from a Triangle of GPS Sites to
Investigate Crustal Strain
UNAVCO GPS Crustal Strain Curriculum Team
September 9, 2012
September 9, 2012
September 9, 2012 Locate three non-colinear GPS sites
September 9, 2012 E-W and N-S components of sites’ velocities
September 9, 2012 E-W + N-S components = total site velocity
September 9, 2012 Total site velocities
September 9, 2012 Define the triangle between the GPS sites
September 9, 2012 Define the centroid of the triangle
September 9, 2012
Transform coordinate system to a new origin at the centroid of the triangle
September 9, 2012
Inscribe a circle in the center of the undeformed triangle
September 9, 2012
The average of the three total site velocities is the translation vector
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.
September 9, 2012
Subtracting the translation vector from the site velocities brings the two triangle centroids together.
September 9, 2012
Subtracting the translation vector from the site velocities brings the two triangle centroids together.
September 9, 2012
The total site velocities minus the translation vector yields the site vectors associated with the change in shape of the triangle.
September 9, 2012
The red line is the major axis of the strain ellipse, and the blue line is the minor axis
September 9, 2012
The ellipse axes remain perpendicular to each other when the strain is reversed.
September 9, 2012
September 9, 2012
The rotational component of strain is indicated by the angular change in the orientation of the red lines.
September 9, 2012
September 9, 2012
September 9, 2012
