Correcting survey measurements in the western US for tectonic deformation

Dr. Chris Pearson

National Geodetic Survey

NGS Geodetic Advisor for Illinois

 

The western part of the United States is constantly deforming due to the boundary between tectonic plates that runs through this region. As a result, accurate surveying in the western US requires a model describing crustal velocities and earthquakes to allow survey measurements to be corrected for differential movement so that surveys conducted at different epochs may be compared. The National Geodetic Survey (NGS) has developed the HTDP (Horizontal time dependent positioning) software that enables its user to make these corrections. This software must be updated periodically to address the displacements associated with each new earthquake.

This seminar describes how survey measurements are corrected for crustal deformation prior to adjustment, focusing on several new earthquake models that have recently been included in our model plus NGS's efforts to improve the secular field in HTDP by developing a comprehensive model of deformation in the western US. I have given something similar to Eric Calais's class at Purdue and as a brown bag at WU for Doug Wiens. The talk I propose here would be extended to include the results of some work we have been collaborating with Rob McCaffrey on.