# InSAR - surface deformation
*methodologies*

Measures millimetre-scale ground surface displacement by comparing phase differences between repeat SAR passes; good for subsidence, earthquake deformation, and volcanic monitoring.

## Specifications
- **family**: SAR processing
- **requirements envelope**: {"kind":"geometric","gsd_max":20,"repeat_pass_geometry":true,"polarisation_modes":["VV"],"swath_min_km":50}
- **entity type**: methodology
- **last verified date**: 2026-05-22
- **verified by**: sw
- **claim status**: unclaimed
- **attributes**: {"family":"SAR processing","summary":"Measures millimetre-scale ground surface displacement by comparing phase differences between repeat SAR passes; good for subsidence, earthquake deformation, and volcanic monitoring.","requirements_envelope":"{\"kind\":\"geometric\",\"gsd_max\":20,\"repeat_pass_geometry\":true,\"polarisation_modes\":[\"VV\"],\"swath_min_km\":50}"}
- **technology**: radar

## Editorial
Interferometric phase encodes range change between passes. Requires precise orbit knowledge and temporal coherence between acquisitions. [Wikipedia: Interferometric synthetic-aperture radar](https://en.wikipedia.org/wiki/Interferometric_synthetic-aperture_radar)

## Sources
- [wikipedia] | Wikipedia: Interferometric synthetic-aperture radar | https://en.wikipedia.org/wiki/Interferometric_synthetic-aperture_radar | tier=community | accessed=2026-05-22

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Source: https://eo-atlas.org/methodologies/insar-surface-deformation
Maintainer: SpectraWorks B.V. (CC-BY 4.0)