Afghanistan’s Deadly 2025 Earthquake Reveals a Wider Seismic Threat Than Mapped Faults Suggest

When a magnitude 6.0 earthquake tore through the rugged mountains of eastern Afghanistan on 31 August 2025, it did more than shatter villages along the Kunar River valley. It exposed a fundamental blind spot in how scientists and hazard planners understand where the region’s danger truly lies. A new study published in the journal Natural Hazards combines field reconnaissance with satellite radar measurements to show that the ground deformation triggered by the quake was not confined to a single, well-mapped fault line. Instead, the deformation was smeared across a broad corridor of interacting structures, a finding with sobering implications for seismic hazard assessment in one of the most earthquake-prone and least-studied corners of the Himalayan collision zone.

The earthquake struck within the Kunar-Spin Ghar fault system, a zone of active crustal deformation in the Hindu Kush region where the ongoing convergence between the Indian and Eurasian plates is absorbed through a complex interplay of strike-slip, reverse and transpressional faults. The event caused widespread infrastructure damage, triggered landslides and rock avalanches, and left visible surface deformation across terrain so steep and inaccessible that ground-based investigation was severely limited. For a region with a long and destructive seismic history but sparse instrumental coverage, the quake offered a rare and urgent opportunity to observe how deformation is actually distributed in this part of the collision zone.

Led by Hamedullah Torabi of Kabul Polytechnic University, with colleagues from institutions in Afghanistan, India, South Korea and the United Kingdom, the research team carried out field reconnaissance at accessible sites along the affected valleys. Their observations documented structural damage to buildings, ground cracks, slope failures, rock avalanches and newly emerged springs along the Kunar River valley. These ground effects, recorded in difficult and sometimes dangerous conditions, provided the essential field anchor for interpreting what the satellite data would later reveal. Emergent springs in particular can indicate changes in subsurface permeability caused by shaking and fault movement, offering clues about where the crust was disturbed.

The technological heart of the study lies in Persistent Scatterer Interferometric Synthetic Aperture Radar, or PSInSAR, a technique that tracks millimeter-scale ground movements over time by comparing radar reflections from stable features such as rock outcrops, buildings and boulders. The team analyzed time series of Sentinel-1A radar data acquired by the European Space Agency’s Copernicus mission between April and October 2025, processing both ascending and descending orbital passes. Because each viewing geometry is sensitive to a different combination of horizontal and vertical motion, combining the two allows researchers to decompose the observed radar signal into east-west and vertical components of surface displacement, effectively reconstructing a two-dimensional picture of how the ground moved during the earthquake period.

What emerged from the radar analysis was striking. Both the ascending and descending line-of-sight velocity fields revealed a laterally continuous deformation pattern extending for several tens of kilometres along the strike of the fault system. Decomposition of the signal showed dominant horizontal motion, consistent with the strike-slip and transpressional character of the region, accompanied by broader and spatially variable patterns of uplift and subsidence. In other words, the ground was not simply sliding along one clean break; it was warping, rising and sinking across a wide swath of terrain in a manner that reflects the distributed nature of the forces at work beneath the Hindu Kush.

Swath-profile analysis, which examines how velocities change across cross-sections of the deformed zone, pinpointed the strongest east-west velocity gradients south of the mapped Kunar Fault and within or adjacent to the Spin Ghar mountain-front structural corridor. This detail matters enormously. The most intense deformation did not coincide neatly with the fault trace that appears on existing maps. Instead, it spilled into neighboring structures, indicating that the earthquake-period deformation signal was shared among multiple interacting faults rather than released on a single rupture plane. The pattern is exactly what geologists would expect from distributed transpressional deformation, a regime in which crustal blocks are simultaneously squeezed and sheared, forcing strain to spread across networks of faults rather than concentrate on one master structure.

The concept of transpression, formally described in the structural geology literature in the 1980s, describes deformation that combines pure compression with a component of shear, producing complex fault geometries and strain partitioning. Eastern Afghanistan sits squarely within such a regime. The India-Eurasia collision, which has built the Himalaya and the Tibetan Plateau, transmits enormous compressive stresses deep into the Asian interior, and the Hindu Kush is one of the places where those stresses find release through intracontinental faulting. Previous studies, including GPS-based measurements of plate convergence partitioning in the Pamir-Hindu Kush region and historical catalogs of Afghan earthquakes, have long suggested the region is tectonically active, but the density of observations needed to map how strain is actually distributed has been lacking.

The new results carry a direct and uncomfortable message for seismic hazard assessment. Hazard models typically rely on mapped fault traces to define the locations and widths of potential rupture zones, and building codes and land-use planning follow from those definitions. If deformation in the Kunar-Spin Ghar system is distributed across a corridor tens of kilometres wide rather than focused on individual mapped faults, then hazard assessments based only on those traces may underestimate both the width of the active deformation zone and the spatial extent of ground deformation and secondary hazards such as landslides, rock avalanches and liquefaction. Communities located well away from any mapped fault trace could still sit within the zone of strongest shaking and ground failure in a future event.

The vulnerability of the region amplifies these concerns. Eastern Afghanistan combines steep, landslide-prone topography, dense rural populations living in unreinforced masonry construction, and limited institutional capacity for emergency response, a combination that recent earthquakes in the region have shown to be lethal. The study’s authors, along with earlier researchers who have called for greater earthquake resilience across Central Asia, argue that satellite-based deformation monitoring offers a practical path forward in terrain where traditional field mapping and dense seismic networks are difficult to establish. Because Sentinel-1 radar data are freely available through the Copernicus Open Access Hub, the approach demonstrated here could be extended systematically across Afghanistan and neighboring countries to build a more realistic picture of active deformation corridors.

The 2025 Asadabad-Kunar earthquake lasted only seconds, but its scientific legacy may prove durable. By pairing boots-on-the-ground observation with space-based radar, the research team has shown that the Hindu Kush does not obey the tidy assumption that earthquakes follow the fault lines drawn on maps. The active deformation zone is wider, more interconnected and more structurally complex than previously recognized, and the seismic hazard it poses is correspondingly broader. For the millions of people who live in the shadow of the Spin Ghar mountains, that widened hazard corridor is not an abstract geodynamic detail. It is a warning that the ground beneath their villages can move in places no map currently marks, and that planning for the next earthquake must account for a danger that is distributed, not localized.

Subject of Research: Distributed transpressional deformation and seismic hazard implications of the 2025 Mw 6.0 Asadabad-Kunar earthquake in eastern Afghanistan

Article Title: Evidence for distributed transpressional deformation and seismic hazard implications from the 2025 Mw 6.0 Asadabad- Kunar earthquake, Eastern Afghanistan

Article References: Torabi, H., Kandregula, R. S., Naik, S. P., Shnizai, Z., Ghildiyal, D., Chufal, V. S., & Kim, Y.-S. (2026). Evidence for distributed transpressional deformation and seismic hazard implications from the 2025 Mw 6.0 Asadabad- Kunar earthquake, Eastern Afghanistan. Natural Hazards, 122(18), Article 624. https://doi.org/10.1007/s11069-026-08397-y

Image Credits: AI Generated

DOI: 10.1007/s11069-026-08397-y

Keywords: Afghanistan, Hindu Kush, earthquake, transpressional deformation, PSInSAR, Sentinel-1A, Kunar fault, Spin Ghar, seismic hazard, India-Eurasia collision, strain partitioning, landslides