Question 1

What does InSAR measure?

Accepted Answer

It measures relative change in satellite-to-ground distance between radar acquisitions. A single viewing geometry gives line-of-sight displacement.

Question 2

Can InSAR show three-dimensional movement?

Accepted Answer

Multiple viewing geometries and justified assumptions can estimate selected components. A single series is never full 3D motion.

Question 3

What accuracy should we expect?

Accepted Answer

On suitable, coherent targets, a sensible planning expectation for long-term line-of-sight velocity is about 2–5 mm/year. With a long, high-quality time series and strong persistent radar targets or properly installed corner reflectors, precision can approach 1 mm/year. The defensible result still depends on the site, radar geometry, atmosphere, reference stability and validation.

Question 4

How far back can an analysis go?

Accepted Answer

It depends on mission archives, geometry and usable surface response. Some European locations have suitable SAR records extending into the 1990s.

Question 5

How often can results be updated?

Accepted Answer

Cadence follows satellite acquisitions and processing design. The useful interval may differ from the nominal revisit time.

Question 6

Does vegetation affect the result?

Accepted Answer

Dense or changing vegetation can reduce coherence. Longer wavelengths, artificial targets or ground instruments may improve the design.

Question 7

What is a reference point?

Accepted Answer

A declared location or reference model anchors relative displacement values. Its stability and uncertainty are part of interpretation.

Question 8

What is PSI or PSInSAR?

Accepted Answer

It uses stable radar targets observed across many acquisitions to estimate displacement time series and reduce atmospheric effects.

Question 9

When is a corner reflector useful?

Accepted Answer

A well-sited corner reflector creates a stable passive radar response where natural targets are weak. It needs clear visibility and durable installation.

Question 10

How does an active target differ?

Accepted Answer

An active target receives and retransmits a controlled signal. It can produce a strong response but needs power, configuration and maintenance.

Question 11

Can InSAR prove structural damage?

Accepted Answer

It records surface or target displacement. Engineering assessment determines structural condition and significance.

Question 12

Can it determine claim causation?

Accepted Answer

It can add an independent chronology and spatial pattern. Causation and liability require the complete evidential record.

Question 13

What do we receive?

Accepted Answer

Scope-specific outputs can include feasibility findings, maps, time series, quality indicators, technical notes and controlled web access.

Question 14

What information starts a feasibility review?

Accepted Answer

Provide a polygon or asset list, decision horizon, suspected movement, relevant survey history and required delivery date.

Question 15

How are sensitive sites handled?

Accepted Answer

Commercial work is private by default. Public examples remain anonymised unless written disclosure is authorised.

Question 16

How do ascending and descending orbits help?

Accepted Answer

Different viewing directions can separate components of movement when geometry and data quality support a justified decomposition.

Question 17

How are satellite results validated?

Accepted Answer

The plan may combine GNSS, levelling, LiDAR, site records, kinematic models or designed radar targets. The choice follows the decision and expected motion.

Question 18

Who owns the outputs and source data?

Accepted Answer

Project deliverables and use rights are defined in the contract. Satellite-source licences and third-party datasets keep their own terms.

Question 19

What drives project pricing?

Accepted Answer

Area, archive depth, acquisition cadence, processing complexity, validation, delivery format, licence terms and reporting effort shape the quotation.

Question 20

Can InSAR predict a failure?

Accepted Answer

It measures past and continuing relative displacement. Safety decisions and failure assessment require the responsible engineers and additional evidence.

Question 21

Is satellite revisit the same as delivery frequency?

Accepted Answer

Revisit is the sensor acquisition interval. Delivery also depends on data availability, processing, quality control and the agreed reporting cycle.

01What does InSAR measure?

02Can InSAR show three-dimensional movement?

03What accuracy should we expect?

04How far back can an analysis go?

05How often can results be updated?

06Does vegetation affect the result?

07What is a reference point?

08What is PSI or PSInSAR?

09When is a corner reflector useful?

10How does an active target differ?

11Can InSAR prove structural damage?

12Can it determine claim causation?

13What do we receive?

14What information starts a feasibility review?

15How are sensitive sites handled?

16How do ascending and descending orbits help?

17How are satellite results validated?

18Who owns the outputs and source data?

19What drives project pricing?

20Can InSAR predict a failure?

21Is satellite revisit the same as delivery frequency?