A growing ground collapse in Pondok Balik Village, Ketol District, Aceh Tengah Regency, Indonesia, currently covers approximately 3 ha (7.4 acres) and continues to expand. As of February 16, 2026, the active edge of the collapse is between 300–400 m (984–1 312 feet) from residential areas.
Long-Term Ground Movement
The ground movement began with cracks and shallow depressions noticed in the early 2000s, developing into visible fractures by 2004. By 2006, the movement disrupted a local transport route, leading to formal geological monitoring starting in 2011. The Aceh Energy and Mineral Resources Office, known as ESDM Aceh, has periodically measured the affected area since then.
Recent investigations, documented in a January 27, 2026, letter from ESDM Aceh, confirm repeated landslides in Pondok Balik since 2011. Ground deformation covered approximately 2.8 ha (6.9 acres) as of May 30, 2022, and has since expanded to approximately 3 ha (7.4 acres).
Geological Factors
Investigations across four districts – Ketol, Kebayakan, Lut Tawar, and Bintang – determined the slope consists primarily of tuff and sandy volcanic rock from the Geureudong Formation. This rock type rapidly weathers and loses strength when saturated with water. Continuous subsurface water flow further erodes the area, weakening the slope’s structure.
Water-saturated zones have been detected beneath the surface, and aerial imagery shows the mass moving southeast and south, with further expansion anticipated in those directions. The steep slope gradient also contributes to instability, and intense rainfall or seismic activity could trigger additional movement.
Infrastructure and Response
Extra High Voltage Overhead Transmission Line (SUTET) towers are located along the expected path of the movement. PT PLN relocated sections of the 150 kV Bireuen to Takengon transmission corridor and installed emergency support structures to prevent power disruptions as the collapse neared tower foundations.
The Ministry of Public Works plans to stabilize the area by injecting grout into cavities, redirecting surface and river water, sealing wet caves, and reinforcing the soil along the road corridor. Approximately 400 m (1 312 feet) of the main road is at risk, with a 5.2 km (3.2 mile) alternative route planned for employ if necessary.
The Regent of Central Aceh noted that the affected area is important for chili cultivation and warned that further widening could damage farmland and infrastructure. ESDM Aceh recommends residents avoid landslide-prone areas, including the affected road.
Frequently Asked Questions
When did the ground movement begin?
Cracks and shallow depressions were first noticed in the early 2000s, developing into visible ground fractures by 2004.
What is causing the ground movement?
Investigations determined the slope is composed of tuff and sandy volcanic rock that weathers rapidly when saturated, and continuous subsurface water flow erodes the area.
What is being done to address the situation?
The Ministry of Public Works plans to stabilize the area by injecting grout, redirecting water, sealing caves, and reinforcing the soil. PT PLN has also relocated transmission lines and installed support structures.
Given the ongoing expansion and the potential impact on infrastructure and farmland, what long-term strategies might be considered to mitigate the risks associated with this geological instability?
