BRIN: Lubang Raksasa di Aceh Bukan Sinkhole, Ini Penyebabnya

A massive land collapse in Ketol, Aceh Tengah, Aceh, Indonesia, continues to expand, now covering an area of 27,000 square meters. The National Research and Innovation Agency (BRIN) has determined that the phenomenon is the result of a landslide, not a sinkhole.

Landslide, Not Sinkhole, According to BRIN

Adrin Tohari, Head of the Center for Geological Disaster Research at BRIN, explained that the Ketol area is not composed of limestone – the type of rock typically associated with sinkhole formation. Instead, the area consists of tufa material originating from the activity of the inactive Mount Geurendong. This tufa, Adrin stated, is a young layer that has not fully consolidated, making it susceptible to collapse.

“What happened in Aceh Tengah is actually a landslide phenomenon, not a sinkhole. The tufa layer is not dense and has low strength, making it very easily eroded and collapsed,” Adrin clarified on Saturday, February 21, 2026.

Did You Know? Analysis of Google Earth imagery dating back to 2010 reveals that a small valley in the Ketol area had been gradually widening over time due to erosion and landslides.

Contributing Factors to the Expanding Collapse

BRIN suggests that a 6.2 magnitude earthquake that struck Aceh Tengah in 2013 likely weakened the slope structure, contributing to the instability. Heavy rainfall is also a primary factor, as the fragile tufa rock readily absorbs water, reducing its cohesion and leading to collapse. Open irrigation channels in nearby plantations are also believed to exacerbate the issue by increasing soil moisture.

Adrin Tohari hypothesizes that subsurface water flow is eroding the boundary between the fragile tufa layer and the more solid rock beneath, causing the upper portion of the slope to lose support and gradually collapse. He emphasized that this is not a sudden event, but a process unfolding over decades or even centuries.

Expert Insight: The identification of tufa as the primary geological component of the affected area is crucial. Unlike limestone, tufa’s porous and unconsolidated nature makes it particularly vulnerable to the combined effects of seismic activity and prolonged rainfall, explaining the gradual but persistent expansion of the land collapse.

Similar Geological Phenomena

BRIN notes that similar conditions can be found in other regions with volcanic rock formations. Ngarai Sianok in West Sumatra, for example, was formed through a long geological process related to the Sumatran Fault and features similar rock characteristics.

Currently, BRIN’s assessment is based on satellite imagery and publicly available data. A comprehensive on-site investigation is needed to confirm the precise causes of the collapse.

Frequently Asked Questions

What caused the land collapse in Aceh Tengah?

BRIN determined the land collapse is a result of a landslide, caused by the erosion and collapse of a tufa layer, not a sinkhole.

What role did the 2013 earthquake play?

The 6.2 magnitude earthquake in 2013 is believed to have weakened the slope structure, accelerating the landslide process.

Is this a sudden event?

According to BRIN, the land collapse is a gradual process that has been occurring over decades, potentially even centuries.

As researchers continue to analyse the situation, will updated vulnerability maps be crucial for mitigating future risks in similar geological areas?