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You can certainly measure this with current surveying techniques. What the satellite InSAR technology allows is the measurement of millions of points at the sam
by jdehls 10y ago
You can certainly measure this with current surveying techniques. What the satellite InSAR technology allows is the measurement of millions of points at the same time, over thousands of square kilometres. And with the Sentinel-1 satellites providing free images every 6 or 12 days, the measurements can be updated frequently.
- notahacker 10y agoAuthoritative third party records that establish the period over which a building or land started to move is also potentially useful in resolving disputes over who and what might be responsible for the movement (nb: I'm currently working with startup that consults on satellite/legal issues)
- Animats 10y agoYou can certainly measure this with current surveying techniques. Not easily. And compared to what? The classic USGS survey markers don't have their height measured accurately enough, and they move with the land. The USGS does have precision "vertical control point" markers, and there are about ten of them along the northeastern coast of San Francisco. The highest precision vertical control point nearby is a GPS station on top of Building 1 at Fort Mason, and its height is valid only to 1.35cm accuracy at 95% confidence.[2] Absolute elevation is tough to measure at those scales. Relative elevation, relative to the average of all ground points for, say, a kilometer radius, is something a radar satellite can do well. [1] https://www.ngs.noaa.gov/NGSDataExplorer/ https://www.ngs.noaa.gov/NGSDataExplorer/ [2] http://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=AF8575 http://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=AF8575