loilo City – Five residents of Barangay Oringao in Kabankalan City, Negros Occidental fell down a sinkhole in the evening of June 26, 2014.
Regional Director Leo Van V. Juguan with senior geologist Dr. Lelanie O. Suerte of the Mines and Geosciences Bureau Region-6 (MGB-6) went on an ocular inspection of the sinkhole on June 28, 2014 after the Local Disaster Risk Reduction Management Council (LDRRMC) of Kabankalan City reported the incident to them through Short Message Service (SMS).
The sinkhole was funnel-shaped (“imbudo” in local dialect) and measures about 3.5 meters in diameter and 3 meters in depth. It had an opening of around 1.7 meters according to Dr. Suerte.
Local resident Jose Gellang in an interview said the five victims were strolling in the basketball court of the barangay mini-plaza at around 9 in the evening of June 26 when suddenly they fell into the sinkhole.
Gellang said the victims were found unconscious by the rescuers and were rushed to the hospital. The rescuers themselves also went unconscious because of the smell of gas inside the sinkhole, Gellang added. The victims and rescuers have recovered and were out of the hospital by the time of the MGB-6 inspection.
RD Juguan said his office will give a formal report to the local government based on the ocular inspection. “One of our recommendations is that a more in-depth study should be done on the area specifically to find out the extent of the existing sinkhole and potential presence of other sinkholes in the area,” Juguan said.
“The study is necessary to determine further steps to ensure the safety of the residents. We will know the safety measures to be taken and the implications to the stability of the area for construction and other development activities,” Juguan further explained.
Dr. Suerte said that the sinkhole was “an action of water” or caused by water as there are no tunnels near the area. “It is possible that the sinkhole might have a wider diameter below the surface but only a portion on the surface has collapsed and gave an opening,” Suerte added.
Local residents said that there were 3 old sinkholes surrounding the area where the sinkhole recently collapsed.
The U.S. Geological survey defines a sinkhole as “an area of ground that has no natural external surface drainage–when it rains, all of the water stays inside the sinkhole and typically drains into the subsurface.”
“Sinkholes are common where the rock below the land surface is limestone, carbonate rock, salt beds, or rocks that can naturally be dissolved by groundwater circulating through them. As the rock dissolves, spaces and caverns develop underground.” (LAA, MGB-6).