Earth is a very small part of a vast universe, but it is our home. It provides the resources that support our modern society and the ingredients necessary to maintain life. Knowledge of our physical environment is critical to our well-being and vital to our survival.

Earth is a very small part of a vast universe, but it is our home. It provides the resources that support our modern society and the ingredients necessary to maintain life. Therefore, knowledge of our planet is critical to our well-being and, indeed, vital to our survival. The science of geology contributes greatly to our understanding of planet Earth. Media reports frequently remind us of the geological forces at work on our planet.

The past decades have witnessed a tremendous improvement in our ability to precisely measure deformation of the earth’s crust. Prior to the advent of space-based geodetic systems, crustal strains were measured by triangulation, leveling, and following the advent of lasers, Electronic Distance Meters (EDM). Very Long Baseline Interferometry (VLBI) was the first system to determine relative motion of sites at intercontinental distance scales and thus measure contemporary rates of platemotion.