This post was originally published on here
The Konya Basin, situated in Central Anatolia, Turkey, is exhibiting signs of rapid ground subsidence, despite being part of a broader region that has been uplifting for millions of years. New research based on satellite and ground measurements confirms that the basin surface is actively sinking, even as the surrounding Anatolian Plateau remains elevated. Scientists used GNSS and InSAR data along with seismic imaging, gravity analysis, and laboratory experiments to examine the process. Their findings point to activity deep beneath the surface rather than movement along faults. The study links present-day basin subsidence to changes in the mantle lithosphere, suggesting a complex and ongoing interaction between deep Earth processes and surface topography. The work adds detail to how large plateaus evolve internally while appearing stable from a distance.
Central Turkey is sinking while the land around it is rising
The Konya Basin lies within the interior of the Central Anatolian Plateau, a broad high region in the middle of Turkey. The plateau stands at an average elevation of around 1.5 to 2 kilometres, with mountain belts marking its northern and southern edges. In contrast, the basin itself forms a low-lying and largely flat depression within this elevated landscape.Geologically, the basin is endorheic, meaning it has no outlet to the sea. It preserves long records of sediment accumulation, largely because material is not removed by external drainage. These sediments include lake deposits that continued to form into the Pleistocene period, leaving behind clear shorelines from an ancient lake system.
Konya Basin is sinking inside Turkey’s rising plateau
Recent GNSS and InSAR observations reveal that the Konya Basin is undergoing active vertical subsidence. This downward motion is localised and circular in shape, centred on the basin interior. At the same time, surrounding parts of the Central Anatolian Plateau show no comparable sinking.The region is considered tectonically quiet compared with eastern and western Anatolia. Apart from the Tuz Gölü fault, no major active fault systems are cutting through the plateau interior. This lack of strong surface tectonics suggests that the subsidence observed in Konya is not driven by crustal fault movement.
Scientists traced subsidence in Turkey’s Konya Basin
Seismic studies show that Central Anatolia has a relatively thin lithosphere, with the boundary between lithosphere and asthenosphere lying at depths of roughly 60 to 100 kilometres. Beneath the Konya Basin, researchers identified a fast seismic wave speed anomaly between 50 and 80 kilometres deep.Such anomalies are commonly interpreted as colder and denser lithospheric material. In addition, crustal thickness beneath the basin reaches around 40 kilometres, with slightly thicker crust at the basin margins. Gravity and topography analysis also reveals a local depression in residual topography of up to 280 metres, indicating that the surface is lower than expected from crustal structure alone.
Why are mantle processes being considered
The combination of subsidence, fast seismic anomalies, and negative residual topography points to processes operating in the mantle rather than at the surface. Researchers interpret these signals as evidence of a mantle lithospheric drip beneath the basin.A lithospheric drip occurs when the dense lower lithosphere detaches and sinks into the underlying mantle. As it descends, it can pull the overlying crust downward, producing surface subsidence. Similar features have been documented in other regions worldwide, including parts of the Sierra Nevada, the Altiplano plateau, and the Puna plateau.
Scaled experiments show lithospheric dripping can form basins
The Central Anatolian Plateau itself has been uplifting since at least the Miocene. Geological and isotopic evidence suggests that large-scale lithospheric removal beneath the region contributed to this uplift over millions of years.The Konya Basin appears to reflect a later and smaller-scale phase of the same process. The study proposes that a secondary drip pulse is developing beneath the basin, occurring at the same time as the plateau remains elevated due to earlier lithospheric loss. Laboratory analogue experiments support the idea that such secondary drips can form and cause localised subsidence within a broader uplifted region.
The findings reveal something about long-term changes in Anatolia
The results of a study titled ‘Multistage lithospheric drips control active basin formation within an uplifting orogenic plateau‘ indicate that basin formation and plateau uplift are not necessarily opposing processes. Instead, they may occur together as part of a multistage evolution of the lithosphere beneath orogenic systems.In the case of Central Anatolia, the surface appears stable over wide areas, yet deep processes continue to reshape the region from below. The Konya Basin offers a clear example of how plateaus can evolve internally long after their main uplift phase, with subtle surface changes reflecting ongoing activity in the mantle beneath.
