Measuring Ground Deformation Using Interferometry
Presentation Time: Mon, 08/01/2022 - 15:00
Keywords: Interferometry, Remote Sensing, Synthetic Aperture Radar, Deformation Measurement
The 2018 earthquake near Big Island, Hawaii caused landslides and ground deformation along the east coast. Ground deformation from seismic activity is of interest to scientists as it gives indications of volcanic activity below the Earth’s surface. Measuring this deformation can be challenging and typically requires Global Positioning System (GPS) monitors in place prior to an event to measure change, however, radar satellites provide a clear picture of wide scale movements. Interferometric Synthetic Aperture Radar (InSAR) is a collection method that compares Synthetic Aperture Radar (SAR) collections to measure vertical and horizontal ground displacement. Specialty software reads these InSAR collections to create an interferogram, a deformation map that precisely measures the ground shift after seismic events, glacial movements, or biomass change. Processing an interferogram starts with raw radar collections from a SAR satellite such as Sentinel-1 and applies a series of corrections and transformations to create measurable data. The final interferogram indicates ground movement from -0.405 meters to +0.185 meters over the most active seismic area in Hawaii. A negative value indicates an underground eruption, or intrusion, which normally causes downslope lava flows while positive values often indicate buckling. The result from the interferogram quantifies the effects of seismic activity and how InSAR can be used to accurately measure deformation for use in planning safe urban and infrastructure growth in areas of seismic activity.
