SEE MOVEMENT. UNDERSTAND WHAT IT MEANS.
InSAR Ground Motion Intelligence for Infrastructure
GeoSmar interprets satellite-derived ground-motion data in a geotechnical context, helping infrastructure teams screen wide areas, review historical movement and compare InSAR trends with ground monitoring.
InSAR Intelligence
Wide-area ground-motion data becomes useful when it is tied back to an engineering question.
Interferometric Synthetic Aperture Radar (InSAR) compares radar observations acquired at different times to estimate movement of coherent points on the ground or on built assets. It can reveal spatial patterns and time histories that conventional point monitoring may not show on its own. GeoSmar focuses on the engineering interpretation of that information: where movement is occurring, how it is changing, whether the pattern is credible, and how it relates to the asset, geology, groundwater, construction or operational context.
InSAR measures movement. It does not, by itself, explain the mechanism.
A subsidence trend may be associated with consolidation, groundwater change, mining, tunnelling, fill settlement or another cause. A slope signal may be consistent with slow landslide movement, but the interpretation still depends on terrain geometry, geology, hydrology and field evidence. The engineering task is to connect the observed deformation with the right project context.
Where InSAR helps
Use InSAR where the project needs spatial context, history or coverage beyond a local instrument network.
The strongest use case is often not “replace the instruments”. It is to extend the field of view and help decide where closer inspection or ground monitoring is justified.
Pre-project ground-motion screening
Review whether an area has a detectable history of slow ground movement before finalising investigation, monitoring or asset-management priorities.
Historical movement assessment
Where suitable radar archives exist, examine whether movement predates construction, a reported defect or the start of ground instrumentation.
Ongoing deformation trends
Track slow displacement patterns over wide areas and compare their evolution with project milestones, groundwater records or local sensors.
Road, rail and utility corridors
Screen long linear assets for differential movement, embankment settlement, slope activity or wider ground deformation that may be difficult to cover densely with field instruments.
Dams, mines and critical facilities
Use spatial deformation patterns as an additional layer when reviewing large or remote assets, subject to suitable radar geometry and coherent measurement points.
Optimising ground monitoring
Use wide-area observations to identify locations that may justify survey checks, instrumentation, inspection or a more detailed engineering investigation.
Engineering workflow
Start with the decision the project needs to make, then choose the InSAR route.
GeoSmar does not assume that every project needs the same satellite, processor, resolution or update interval. The data route should follow the engineering question and the site conditions.
What the engineering review asks
A velocity map is the start of the review, not the conclusion.
A useful interpretation looks at the time series, spatial pattern and project context together. Average velocity alone can hide acceleration, seasonal behaviour, local discontinuities or a change that only began recently.
Spatial pattern
Is movement concentrated on one asset, one slope, one embankment or a broader geological area? Is there a differential pattern across a structure or corridor?
Time behaviour
Is the displacement steady, seasonal, episodic or accelerating? Did the trend change around excavation, dewatering, loading, rainfall or another known event?
Directional meaning
Is the result line-of-sight displacement, vertical displacement or a vertical/east-west decomposition? Different products should not be interpreted as though they measure the same component.
Geotechnical mechanism
Could the pattern be consistent with consolidation, groundwater drawdown, slope movement, tunnelling, mining, fill settlement or another mechanism supported by site evidence?
Data confidence
Are measurement points dense enough and well located for the question? Are there gaps, decorrelation, atmospheric effects, topographic artefacts or reference issues that could affect interpretation?
Engineering follow-up
Does the pattern justify site inspection, survey verification, additional instrumentation, a change in review frequency or a closer look at existing monitoring records?
Limitations that matter
InSAR is powerful because it sees widely. It is reliable only when its limitations are handled explicitly.
Copernicus and USGS guidance is clear that coverage and interpretation are not uniform everywhere. The following issues should be checked before using InSAR as engineering evidence.
Line-of-sight geometry
Vegetation and changing surfaces
Topography, shadow and layover
Water and temporarily flooded surfaces
Fast or abrupt movement
Point location and spatial resolution
Update frequency and warning use
Ground + satellite
The strongest interpretation usually comes from comparing InSAR with evidence on the ground.
USGS describes InSAR as a wide-area deformation tool that can provide insight when combined with ground-based monitoring. Copernicus guidance likewise notes that interpretation depends on ancillary geological, hydrogeological and measurement data.
InSAR contributes
- Wide-area spatial coverage
- Historical deformation where archive data exist
- Dense measurement points over coherent urban surfaces
- Regional context around a local monitoring network
- Time-series comparison across many locations
Ground monitoring contributes
- Direct measurements at selected critical locations
- Subsurface behaviour from inclinometers or extensometers
- Pore pressure and groundwater information
- Survey references and asset-specific geometry
- Higher-frequency or near-real-time measurements where required
| Engineering question | Useful InSAR contribution | Possible ground evidence | Interpretation focus |
|---|---|---|---|
| Is settlement local or regional? | Spatial pattern and time history across the wider area | Levelling, settlement points, GNSS | Differential versus widespread movement |
| Is a slope moving? | Surface displacement pattern where coherence and geometry are suitable | Inclinometer, GNSS, survey, groundwater, rainfall | Movement extent, direction, rate and hydrological relationship |
| Did movement predate construction? | Historical archive assessment where available | Baseline survey, historic reports, GI records | Pre-existing trend versus construction-related change |
| Where should instruments be concentrated? | Wide-area screening for anomalous zones | Targeted site inspection and instrumentation | Risk-based monitoring layout |
Scope & contract points
Define the data product before writing “provide InSAR monitoring” into a contract.
Many technical disputes begin with an underspecified scope. The following items are practical GeoSmar recommendations for defining an InSAR package; they are not presented as clauses from any particular live contract.
- Area of interest and target assets
- Engineering purpose of the analysis
- Historical period required
- Satellite or data-product route
- Spatial resolution and expected point density
- Ascending, descending or decomposed products
- Reference frame and datum
- Acquisition and reporting frequency
- Expected processing and delivery latency
- Quality indicators and acceptance criteria
- Handling of low-coherence or no-data areas
- Raw, processed and interpreted deliverables
- Data format, GIS export and API needs
- Ground-monitoring integration requirements
- Data ownership, licence and retention
- Engineering review and sign-off responsibility
- Trigger use and notification boundaries
- Change-control process if the monitoring question changes
Official international evidence
Public-sector and industry examples show where InSAR adds value — and where engineering interpretation remains essential.
The examples below are published by official agencies or the named technology providers. They are included as industry context only and are not GeoSmar projects.
Oslo train station, Norway
ESA reported that Sentinel-1 observations acquired from December 2014 to October 2016 showed parts of Oslo train station sinking by about 10–15 mm/year in satellite line of sight, corresponding to roughly 12–18 mm/year of vertical subsidence. The example demonstrates how a transport asset can be viewed in the context of surrounding urban ground motion.
Piemonte geohazards, Italy
Copernicus describes how ARPA Piemonte uses European Ground Motion Service data together with monitoring networks and other sources for landslide assessment. The published Grange Orgiera example notes major historic displacement and damage to a local road, illustrating the value of combining regional ground-motion information with local hazard management.
Land subsidence monitoring, United States
USGS describes InSAR as a high-density measurement method for detecting changes in land-surface altitude over large areas and uses it in land-subsidence investigations. The official guidance also stresses that the technique is affected by land cover, atmospheric effects and other error sources.
European infrastructure-scale ground motion
The Copernicus European Ground Motion Service uses Sentinel-1 InSAR to provide ground-motion information across Europe. Copernicus identifies applications including dams, bridges, railways, roads and buildings, while its technical documentation also sets out important limitations on coverage, geometry and measurement interpretation.
GeoSmar role
GeoSmar sits between satellite-derived displacement and the engineering decision.
The commercial value is not another coloured deformation map. It is an independent engineering view of what the pattern means, what the data does not prove, how it compares with ground monitoring, and what should be checked next.
Engineering scoping
Define the asset, movement question, required historical period, useful update interval and data quality needed before choosing the InSAR route.
Independent interpretation
Review spatial patterns, time series, reference assumptions, quality indicators and limitations without treating the processing output as a complete geotechnical conclusion.
Ground-data correlation
Compare InSAR trends with survey, settlement, inclinometer, groundwater or other monitoring where those datasets are available and relevant.
Targeted diagnostics
Investigate areas where satellite and ground observations disagree, where apparent movement changes suddenly, or where a client needs an independent view of the evidence.
Portfolio screening
Apply a repeatable review framework across multiple corridors, sites or assets where the selected data product provides suitable coverage.
Engineer-reviewed reporting
Separate measured or processed information from interpretation, assumptions, limitations and recommended engineering follow-up.
Frequently asked questions
InSAR is most useful when the project understands exactly what it can and cannot answer.
Can InSAR replace inclinometers, settlement points or survey monitoring?
Can InSAR show historical movement before a project started?
Does a red point on an InSAR map mean the ground is unsafe?
Can InSAR determine why the ground is moving?
Can InSAR be used as a real-time alarm system?
Does GeoSmar process raw SAR data?
What should a client send for an initial discussion?
Official technical sources
Primary sources used for this page.
The technical statements and case context on this page are based on official government, intergovernmental, space-agency and named provider publications. Provider links are included as industry context and do not imply a GeoSmar partnership or endorsement.
Copernicus Land Monitoring Service — European Ground Motion Service
Service overview, infrastructure applications, datasets and ground-motion context.
Copernicus — EGMS limitations
Coverage, vegetation decorrelation, measurement-point localisation and spatial-resolution limitations.
Copernicus — EGMS Product User Manual
Detailed guidance on interpretation, surface conditions, topography, vegetation, water, snow and methodological constraints.
Copernicus — EGMS Algorithm Theoretical Basis
Line-of-sight geometry, coherence, persistent and distributed scatterers, motion-rate limitations and ascending/descending observations.
U.S. Geological Survey — InSAR
Principles of InSAR, high-density land-surface deformation measurements and ground-subsidence applications.
U.S. Geological Survey — Monitoring Ground Deformation from Space
Explanation of InSAR and its use together with ground-based monitoring.
European Space Agency — Oslo train station
Official Sentinel-1 example showing measured subsidence at Oslo station.
Copernicus — Piemonte geohazards
Government use of EGMS with other monitoring information for landslide assessment and regional risk management.
SkyGeo — InSAR for civil engineering
Industry context on historical screening, construction monitoring, infrastructure maintenance and the use of InSAR alongside conventional monitoring.
Sixense — Atlas InSAR
Industry context on recurring satellite monitoring, infrastructure applications, multi-sensor integration and reporting workflows.
Start with the engineering question
Have an asset or corridor where ground movement needs a wider view?
Send the location, area of interest, project stage and the question you are trying to answer. If ground-monitoring or survey data already exist, include a sample. GeoSmar can help define whether InSAR adds useful evidence and how it should be integrated into the monitoring review.