Sinkholes, caves found in Bohol team seeks suspension of infrastructure works

CEBU, Philippines - The Sinkhole Assessment Team (SAT) of the Mines and Geosciences Bureau (MGB), in cooperation with the volunteer Filipino Cave Divers (FCD), had suggested to authorities to suspend the ongoing infrastructure works for at least a year and consult structural engineers on the subsurface conditions of Bohol.

Apparently some of the sinkholes were still subsiding further into the ground, and SAT planned to survey all vulnerable parts of Bohol island and complete its study this year.

Hundreds of sinkholes appearing in Bohol after the 7.2-magnitude earthquake that hit the island last year and new underwater caves in Cebu and Mindanao were the focal topics discussed during the 18th National Cave Committee (NCC) meeting, chaired by Biodiversity Management Bureau (BMB) director Mundita Sison Lim, last Feb. 23, at the National Museum in Tagbilaran City.

The BMB is DENR’s newest agency that replaced the smaller Protected Areas and Wildfire Bureau, which Lim also headed before.

In a presentation by the SAT from the MGB, led by Supervising Science Research Specialist Liza Socorro Manzano, at least 627 sinkholes were identified based on NAMRIA topographic map of scale 1:50,000 in southwestern parts of Bohol island.

A total of 111 sinkholes were thoroughly examined by ground penetrating radar, each of which was found to have its own unique characteristic leading to better understanding of the subsidence susceptibility of the island.

The study showed that Bohol is teeming with underground chambers and passages. Allan Fernando, a geologist from the UP National Institute of Geological Sciences, coined the term “ampao” to describe Bohol’s seemingly porous underground. Ampao is a popular Visayan delicacy of fried rice brittle where the rice granules are loosely packed.

The FCD group, of Dr. Alfonso Amores and Jake Miranda, also presented the completed penetrations of underwater caves inside Lake Bababu in Dinagat Islands, Hinatuan Enchanted River, Pamuntuanan and Campamento-Lanuza  (all in Surigao del Sur), and Pawod and Casili Spring in Cebu.

Amores pointed out that some of the country’s once impenetrable caves can now be explored and their distances and ranges extended past the water barriers. The NCC lauded Amores’s group for its efforts to pioneer scientific underwater cave exploration.

Lim immediately recommended a memorandum of agreement to be signed between her bureau and FCD to fast-track protocols in cave diving exploration all across the country.

“With cave diving expertise now locally available, we now have a partner in FCD to finally explore the numerous freshwater and sea caves in the different parts of the country. Previously we had to rely on foreign expertise. This partnership boosts our local capability to conduct studies on cave geology and biodiversity inside the underwater caves,” she added.

The SAT, composed of geologists and academicians was created by DENR Secretary Ramon Paje and supervised by MGB Director Leo Jasanero. FCD is composed of Filipino technical cave divers, scientists and volunteers.  (FREEMAN)