The USGS employs a variety of methods, including LIDAR, the Global Positioning System (GPS), Interferometric Synthetic Aperture Radar (InSAR), creepmeters, and alinement arrays to make geodetic measurements. Geodetic measurements of crustal motion are uniquely suited to observing a range of processes relevant to earthquake occurrence and effects that cannot be observed with other methods such as seismology.
The motions captured by these diverse measurement techniques provide vital information on:
- The slow ‘background’ tectonic motions between the earth’s plates, thereby constraining the buildup of stress on faults.
- The offsets across creeping faults such as the Hayward fault, which results in steady motions (typically several millimeters per year) of blocks of crust moving past each other along a common fault boundary.
- The offsets across a fault during a large earthquake (the coseismic displacements).
- Rapidly decaying motions that persist for weeks to years after a large earthquake, arising from a combination of continued slip on the fault (‘afterslip’) and possibly its extension into the lower crust and flow of rock in the deeper lower crust and mantle, where the temperature is high enough to permit ductile flow.
In parts of the U.S. with few or no recorded major earthquakes, or where background seismicity is sparse, geodetic data may provide the only insight into present-day seismic hazard. Furthermore, geodetic datasets represent the best chance to assess aseismic deformation processes (or those processes that are occurring between earthquakes, or without earthquakes at all).
The Deformation Project strives to address problems relevant to earthquake loss reduction using geodetic data in combination with other data types as appropriate, including but not limited to:
- Assessing the degree to which post-seismic deformation from past earthquakes affects estimates of interseismic strain accumulation rates
- Evaluating apparent discrepancies between geodetic and geologic estimates of deformation rates, slip rates, earthquake magnitudes, and recurrence intervals
- Constraining fault frictional properties and the rheology of the crust and upper mantle
- Improving earthquake early warning and rapid response in concert with the EEW project using real time high-rate GPS data
- Investigating the implications of transient deformation for earthquake probability
- Acquiring, reporting on, and interpreting geodetic data as an integral part of the scientific response and situational awareness efforts following significant earthquakes
- Developing new techniques for acquiring geodetic measurements, including seafloor measurements and fiber-optics
- Applying these methods to the full suite of tectonics in the US, including major subduction zones
- Applying these methods to better understand how sources of anthropogenic deformation may be separable from natural ones, in close cooperation with the Induced Seismicity project
See Also:
The USGS employs a variety of methods, including LIDAR, the Global Positioning System (GPS), Interferometric Synthetic Aperture Radar (InSAR), creepmeters, and alinement arrays to make geodetic measurements. Geodetic measurements of crustal motion are uniquely suited to observing a range of processes relevant to earthquake occurrence and effects that cannot be observed with other methods such as seismology.
The motions captured by these diverse measurement techniques provide vital information on:
- The slow ‘background’ tectonic motions between the earth’s plates, thereby constraining the buildup of stress on faults.
- The offsets across creeping faults such as the Hayward fault, which results in steady motions (typically several millimeters per year) of blocks of crust moving past each other along a common fault boundary.
- The offsets across a fault during a large earthquake (the coseismic displacements).
- Rapidly decaying motions that persist for weeks to years after a large earthquake, arising from a combination of continued slip on the fault (‘afterslip’) and possibly its extension into the lower crust and flow of rock in the deeper lower crust and mantle, where the temperature is high enough to permit ductile flow.
In parts of the U.S. with few or no recorded major earthquakes, or where background seismicity is sparse, geodetic data may provide the only insight into present-day seismic hazard. Furthermore, geodetic datasets represent the best chance to assess aseismic deformation processes (or those processes that are occurring between earthquakes, or without earthquakes at all).
The Deformation Project strives to address problems relevant to earthquake loss reduction using geodetic data in combination with other data types as appropriate, including but not limited to:
- Assessing the degree to which post-seismic deformation from past earthquakes affects estimates of interseismic strain accumulation rates
- Evaluating apparent discrepancies between geodetic and geologic estimates of deformation rates, slip rates, earthquake magnitudes, and recurrence intervals
- Constraining fault frictional properties and the rheology of the crust and upper mantle
- Improving earthquake early warning and rapid response in concert with the EEW project using real time high-rate GPS data
- Investigating the implications of transient deformation for earthquake probability
- Acquiring, reporting on, and interpreting geodetic data as an integral part of the scientific response and situational awareness efforts following significant earthquakes
- Developing new techniques for acquiring geodetic measurements, including seafloor measurements and fiber-optics
- Applying these methods to the full suite of tectonics in the US, including major subduction zones
- Applying these methods to better understand how sources of anthropogenic deformation may be separable from natural ones, in close cooperation with the Induced Seismicity project