Key facts
| Data | Value | Source |
|---|---|---|
| What it measures | Ground rising or sinking, in mm a year | Copernicus Land Monitoring Service — European Ground Motion Service (EGMS) |
| Satellites | Sentinel-1 radar (EU Copernicus) | Copernicus Land Monitoring Service — European Ground Motion Service (EGMS) |
| Updates | Once a year | Copernicus Land Monitoring Service — European Ground Motion Service (EGMS) |
| Ortho product grid | 100 × 100 metres | Copernicus Land Monitoring Service — EGMS Ortho: vertical and east-west components on a 100 m grid |
| Release used by the report | 2019-2023 | Copernicus Land Monitoring Service — EGMS Ortho: vertical and east-west components on a 100 m grid |
| Subsidence in the Guadalentín valley (Murcia) | Over 10 cm a year in some periods | IGME-CSIC (Spanish Geological Survey) — Basic manual on using InSAR data to measure ground surface displacement (in Spanish) |
| Sinking measured by the EGMS near Lorca | Over 8 cm a year | IGME-CSIC (Spanish Geological Survey) — Basic manual on using InSAR data to measure ground surface displacement (in Spanish) |
What the report tells you
What the report tells you — check 13
Is the ground moving?
It sums up the EGMS points around the building as a vertical speed and compares it with the surroundings to tell you whether the area is stable or worth asking about.
- Median vertical speed in mm a year within 150 metres of the building
- Comparison with a reference ring from 200 to 500 metres
- Spread, gradient and number of points measured
- Points coloured by speed on an aerial photo, with release and lookup date
What the satellite figure tells you
What to do if the area is moving
Read the figure in context
Compare the speed at the building with the surroundings and the number of points.
Ask the owners' association
Recent cracks, doors that stick and settlement repairs.
Ask for any existing reports
Geotechnical or technical studies of the building or the development.
Arrange a technical visit
Before signing the deposit contract (arras), if the movement is significant.
What is the Copernicus EGMS?
The European Ground Motion Service (EGMS) is a free service of the European Union's Copernicus programme that measures from space how much the ground rises or sinks across Europe, with millimetre precision. It relies on radar from the Sentinel-1 satellites and, according to Copernicus, is updated once a year.
The European Ground Motion Service (EGMS) is part of the European Union's Copernicus programme. It uses radar images from the Sentinel-1 satellites and a technique called radar interferometry (InSAR), which compares successive passes over the same place to measure ground displacements of a few millimetres. It is updated every year and covers the countries taking part in Copernicus.
Its data can be viewed and downloaded for free in the explorer at egms.land.copernicus.eu, which shows the two latest releases. The easiest product to read is Ortho: it separates vertical from east-west movement and spreads it over a 100-metre grid, so you do not need to know the satellite's viewing geometry to interpret it.
What does the EGMS measure at each point?
It measures the average speed at which the ground rises or sinks, in millimetres a year, and keeps the displacement at every satellite pass. In the vertical component, a negative value means the ground is going down. According to the IGME, the EGMS shows more than 8 centimetres a year of sinking near Lorca, in Murcia.
Every EGMS point has an average speed in millimetres a year and a time series with the displacement at each satellite pass. In the vertical component, a negative value means the ground is going down and a positive one, that it is going up.
Large figures usually have a known cause. The best-known case in Spain is the Guadalentín valley in Murcia: according to the Spanish Geological Survey (IGME), its aquifer has been heavily pumped for irrigation since the 1960s, subsidence exceeds 10 centimetres a year in some periods, and in the EGMS the ground sinks by more than 8 centimetres a year near Lorca.
What can the satellite figure not tell you?
It cannot judge an individual building or say why the ground moves. The Ortho product averages 100 by 100-metre cells and, according to the IGME, each point's position is accurate only to a few metres. Where there are no points there is no measurement: that is missing data, not ground that is standing still.
The EGMS does not measure an individual building. The Ortho product averages over 100 by 100-metre cells and the position of the points is accurate to a few metres, so, as the IGME warns, it is not suitable for close monitoring of a small building. Nor does it explain why the ground moves or say anything about a building's foundations or cracks.
There are also areas without data: vegetation and crops, water, very steep slopes, snow and land that changed a lot during the release period, such as new construction. Fast or sudden movements are measured poorly, because the processing assumes linear movement, and the service is a historical record, not real-time monitoring. The IGME considers it very valuable for preliminary studies, but no substitute for a dedicated study.
What to do if the area is moving
A high speed in the area is a reason to ask questions, not a conclusion. Ask the owners' association (comunidad de propietarios) about recent cracks in the façade or entrance, doors that stick or repairs for settlement, and whether there is a geotechnical or technical report on the building.
If you are serious about the flat, have a surveyor or structural engineer visit before you sign to look at the structure and the cracks. If the area is stable, do not forget the rest: a building can have problems of its own even when the ground around it is not moving.
How HOUSINGFAX checks it: check 13
Check 13 of the report answers “Is the ground moving?”. It takes the vertical EGMS points of the 2019-2023 release within 150 metres of the building, calculates their median in millimetres a year and compares it with a reference ring from 200 to 500 metres; it adds the spread, the gradient and the number of points, and plots them by colour on an aerial photo from the Spanish national orthophoto programme (PNOA). Using reading thresholds set by HOUSINGFAX, it labels the result stable below 2 mm a year, watch between 2 and 5, and significant movement from 5.
Start with the free report: it shows the check with your building's real data and the key information blurred. To see it in full, the essential report costs €11 and the complete report, which adds the recorded building condition, €19. That is 22 checks on official sources, as a PDF in a few minutes, with a single payment and no account. The report does not replace a technical inspection of the building.
Short answers
What is ground subsidence?
It is the slow sinking of the ground. A well-known case in Spain is the Guadalentín valley (Murcia), where pumping groundwater makes the ground sink by more than 10 centimetres a year in some periods, according to the Spanish Geological Survey (IGME).
How many millimetres a year is a concern?
There is no single official threshold. The HOUSINGFAX report uses its own reading thresholds: stable below 2 mm a year, watch between 2 and 5 and significant movement from 5. A high figure is a reason to ask questions and, if needed, call in a professional.
Does the satellite measure my building?
Not exactly. The EGMS Ortho product gives values for 100 by 100-metre cells, and each point's position is accurate to a few metres. It describes the movement of the area, not of an individual building.
Why is there no data near my building?
Radar needs surfaces that reflect the signal consistently. Data is missing in areas with vegetation or crops, water, very steep slopes, snow or land that changed a lot during the release period. Without points, the report marks the check as no data, never as stable ground.
What should I do if the ground in the area is sinking?
Ask the owners' association about recent cracks and settlement repairs, ask for any geotechnical or technical report on the building and, before you sign, have a professional visit to look at the structure.
Official sources you can consult
The links let you review the primary source. Their inclusion does not widen their purpose or turn a piece of context into a diagnosis.