Where the ground is sinking under Romanian homes

A country drawn by radar#

The map is made of 100 by 100 metre squares that the Sentinel-1 radar satellites could follow from orbit; at country scale, 36 of them are gathered into each 600 m point. Forests, ploughed fields and water do not return a stable signal, so they stay empty; villages, roads and towns appear on their own. There are 1.9 million squares, 466,201 of them built up.

For each square, the EU's Copernicus service calculated how much the ground rose or fell per year between December 2020 and November 2025.

Almost everywhere, nothing#

Under 94 in 100 built-up squares, the ground moved no more than 2 mm a year, up or down. That line is about three times the uncertainty the service itself states for a velocity (0.7 mm a year), so the page treats any value between −2 and +2 mm a year as still.

Only 0.55% of built-up squares, 2,577 of them, sink by at least 5 mm a year. Grouped with their neighbours they form 44 areas with at least ten built-up squares each. On the country map, a 600 m point is lit when at least four of its 100 m squares, and at least a fifth of those measured, sink that fast, whatever the land.

Dumbrăvița: 2 km² going down#

The largest of these areas adjoins the north of Timișoara, Romania's third-largest city, in Dumbrăvița, a separate village municipality on the city's northern edge: 204 built-up squares, about 2 km², sink by at least 5 mm a year. Their median is −9.0 mm a year and the fastest reach −20.2 mm. On average the area fell by 4.9 cm in five years, at a steady rate, without speeding up.

It is not only recently built land. Squares already built up in 2000, according to the European map of buildings, sink too (−8.9 mm a year, median), not just those first built up after 2005 (−5.1 mm a year). The land is flat and does not move sideways, so the landslide check flagged nothing, and the sinking shows separately from both directions the satellites look from.

This was known: a 2015–2020 radar atlas by the company Terrasigna wrote that Dumbrăvița was "slowly subsiding", with its highest values, 8–10 mm a year, on a new estate. The 2020–2025 measurements show that it went on. No published study found for this article establishes the cause.

The plain around Timișoara#

Dumbrăvița is not alone. The same plain has more sinking areas, including one inside Timișoara itself; in brackets, their median in mm a year: Timișoara, north-west (−16.8), Ianova (−18.4) and Giarmata-Vii (−5.8).

Ianova sinks by a median −18.4 mm a year, twice as fast as Dumbrăvița, but over a much smaller area.

The Teleorman plain and the Târnave plateau#

The second kind of place in the ranking is the plain around Videle, south-west of Bucharest: Blejești and its neighbours sink by a median −6.2 mm a year along a strip several kilometres long. Videle is an oil field worked since 1961, and the Terrasigna atlas recorded sinking of 3–9 mm a year here in 2015–2020, over an area more than 20 by 5 km.

On the Târnave plateau near Sighișoara, Daneș, Albești and Apold sink by 8 to 13 mm a year, and near Târgu Mureș, Curteni and its neighbours by about 7 mm a year. For the area near Târgu Mureș the same atlas wrote that it remains to be seen whether the motion is linked to gas extraction and storage or to the slopes. Radar cannot tell the cause, so the page says "near", not "because of".

The salt towns: almost all quiet#

When Romanians talk about ground caving in, the first names are the salt-mine towns. For this article all ten were taken from public lists (Turda, Praid, Cacica, Ocna Dej, Ocna Mureș, Târgu Ocna, Ocnele Mari, Slănic, Ocna Sibiului, Ocna Șugatag), and the rule was written down before the calculation: within 2 km of the mine's point (the mine where it is mapped, otherwise the town centre), at least ten built-up squares sinking by 5 mm a year or more, and their share of built-up squares at least three times the share 4–6 km away. If fewer than three towns passed, the idea was dropped.

Only one passed: Slănic, with 19 sinking built-up squares, down to −11.6 mm a year. Only one of the satellites' two viewing directions covers the area well, and it shows the sinking (−3.1 mm a year against the surroundings). Researchers describe soil being washed by water into voids in the salt here; in April 2024 a street fell into a crater about 2 metres deep. In the national ranking Slănic's area comes only 23rd; none of the top 20 lies within 6 km of the salt-mine points.

At Ocna Mureș the fastest squares (−17.7 mm a year) lie around Lake 23 August and the industrial site beside it, where there are hardly any houses: only 2 of the 9 are built up.

Praid: nothing before, nothing clear after#

The Praid salt mine flooded at the end of May 2025, after the Corund stream rose a hundredfold. The measurement series runs through the flood and on to November 2025.

Before the flood, the ground around the mine was sinking as slowly as the ground 4–6 km away, under 1 mm a year, and not speeding up: the difference in acceleration is 0.03 mm a year squared, far below the noise. Afterwards some squares sink faster, but a similar share do far from the mine (11 per cent around it, 11 per cent 4–6 km away), and six months are too few to tell a trend from a seasonal swing. At this resolution, the measurements showed no warning sign before the flood.