UGM Professor: Amblesan in Gunungkidul The General Phenomenon of Karst Areas

Illustration - Residents who are curious to see up close the sinkhole hole that formed in the middle of the Wilis ring road, Tulungagung, East Java, Thursday (27/2/2025). ANTARA FOTO/Destyan Sujarwoko

YOGYAKARTA - Professor of Environmental Geology at Gadjah Mada University (UGM) Prof Wahyu Wilopo said that the land subsidence in Girikarto Village, Kapanewon Panggang, Gunungkidul Regency is a common phenomenon of karst areas that often appear during the rainy season.

"The sinkhole that occurred in Gunungkidul is actually still in the category of a small sinkhole and is not something surprising, because almost every year, especially during the rainy season, events like this often occur in karst areas," said Wahyu as reported by ANTARA, Monday, January 19.

Wahyu explained that the Gunungkidul area is dominated by limestone which is easily dissolved so as to form underground cavities.

This condition, he said, makes subsidence or sinkholes more likely to occur, especially in areas with high surface water supplies.

"Gunungkidul is dominated by limestone which is easily soluble. Erosion is often found in areas where the surface water is relatively abundant, for example in rice fields or around houses," he said.

He said the presence of septic tanks around residential areas could also trigger subsidence because wastewater that is poured into the ground can accelerate the dissolution process of limestone rocks.

According to Wahyu, the collapse in the karst area has the potential to spread to other points because underground cavities can be interconnected and not only in one layer.

"It is possible that the cavity is not just one layer below. Maybe there is more below, we don't know," he said.

As is known, the land collapse occurred inside a resident's house in Kalurahan Girikarto, Kapanewon Panggang, Gunungkidul Regency, DIY on January 7, 2026.

Regarding the geoelectric test plan to be carried out by the DIY Regional Government, Wahyu assessed that the method was effective in identifying the dimensions of underground cavities, both depth and width.

The results of the geophysics test can provide an initial overview of the subsurface conditions before determining the next handling.

"Usually from the results of the georheological test we can estimate the hole is at what depth and what its dimensions are. That will be seen from the anomaly of its resistivity value," said Wahyu.

Based on the results of the study, according to him, it can be determined whether the subsidence location is still possible to carry out technical engineering or it needs to be temporarily evacuated.

However, Wahyu advised residents to temporarily avoid the location of the landslide until the results of detailed studies on the underground conditions are available.

"My advice is to move away from there as much as possible because it is much safer, unless you have conducted a detailed study to find out what the dimensions are like," said Wahyu.

Regarding the plan to reduce subsidence by residents in Girikarto, Wahyu Wilopo assessed that the step was risky if it was carried out without a thorough study of the underground conditions.

"If the hole is big, the debris can run anywhere. Or it has been cleaned up, but it turns out that it is a waterway, so the debris can be carried away and collapse again suddenly," said Wahyu.