Geodetic methods are used to measure movement of the Earth’s surface and strain in the upper few hundred meters of the Earth’s crust. These data record subtle fault-related deformation of the Earth’s crust that does not generate seismic waves as well as the rapid motion that occurs during earthquakes. Geodetic measurements have applications for seismic hazard assessment, earthquake early warning, earthquake likelihood monitoring, and research into underlying physical processes
Two-color Electronic Distance Meter (EDM)
Results from measuring changes in distances using a two-color EDM. Measurements
were made in Parkfield, Long Valley, and Southern California.
Measurements of the distance between pairs of benchmarks in surveying
networks located in the central and western U.S. and Alaska.
Data were collected between 1959 and 1993.
Long Valley, in eastern California, is the center of continuing volcanic activity and
moderate earthquakes. Links to instrumental monitoring of geophysical activity in the
San Francisco Bay Area
This page examines GPS along with creepmeter and strainmeter data that monitor deformation across the SF Bay region.