Radar satellites have been collecting images around the globe since the early 1990’s. Urban locations in particular typically have a significant amount of archive data available for InSAR analyses. The image below shows SAR data availability across a number of different satellites and orbit paths for San Francisco, CA from 1992 to 2017.
Rural locations have less data available than urban areas, however the Sentinel satellite constellation has been imaging the entire earth on a 6 to 12 day cycle since late 2014. ALOS-1 also typically has 6 – 15 images available for the entire earth acquired between 2007 and 2011.
One-time historical InSAR analyses are used by 3vG’s clients for a number of reasons:
To understand historical slope movement or infrastructure displacement in terms of what moved, when, and by how much. This can be a useful tool for projects involving failure analyses, construction incidents, insurance subrogation, landslides, and lawsuits.
To develop baselines for contemporary data or applications
To locate areas of stability for planning of new development projects (e.g., new pipeline right of ways, new housing developments, etc.)
As a cost-effective approach to help determine an area of interest’s suitability for Ongoing Monitoring.
3vG can conduct a data archive search of all of the relevant satellite image databases to determine data availability over your specific area of interest. If sufficient imagery is available, we can conduct an InSAR analysis of these images to measure displacement over the associated time frame. An example of the type of InSAR results generated from historical archive images for a portion of a major U.S. city is shown in the figure below.