DENR warns against settling in coastal uplift areas in Mindanao

MANILA – The Department of Environment and Natural Resources (DENR) has warned against building any infrastructure, including houses, on newly formed coastal uplift areas in Mindanao following the magnitude 7.8 earthquake on June 8.

In a Radyo Pilipinas interview on Wednesday, DENR-Mines and Geosciences Bureau (MGB) Assistant Secretary Karlo Queaño said it is dangerous to live in coastal uplift areas, citing a similar incident in Bohol in 2013 following a magnitude 7.2 earthquake.

“Kaya po rito sa Mindanao, importante na, although uplifted, kailangan po nating maintindihan kung ang dagat po eventually ay bumabalik din po. Kaya sa ganitong sitwasyon, we really discourage na ito ay tayuan at mas maganda nga po gawing siyang (So here in Mindanao, it is important that although uplifted, we need to understand if the sea will eventually return. So in this situation, we really discourage building on it, and it would be better to make it a) geologic monument,” he said.

Queaño warned that these areas remain vulnerable to geological and climate-related hazards.

He said the coastal uplift in parts of Davao Occidental and nearby areas is a natural consequence of tectonic movement triggered by the powerful earthquake.

“Ang mga coastal uplift po ay isa sa mga potential or isa sa mga manifestation ng deformation na tinatawag na ground deformation as a result of the earthquake. Yan ang tinatawag nating (The coastal uplifts are one of the potential or one of the manifestations of deformation called ground deformation because of the earthquake. That's what we call) coast seismic events,” he said.

After the powerful earthquake, residents reported that portions of the shoreline appeared to rise, exposing areas that were previously underwater, including corals, seabed, and seagrass.

The phenomenon has drawn public curiosity about whether the newly emerged land could be developed for habitation.

Queaño said scientists are still studying the extent of the changes, but stressed the need for caution, noting the rising sea levels in the Philippines.

“Sa Pilipinas po ay medyo komplikado kasi very active tayo technically at in the same way sa (In the Philippines, it's a bit complicated because we are very active technically and in the same way in the) Philippines, we are affected by the relative sea level rise. In fact, in the eastern seaboard, it's actually three times faster than the global average,” he added.

Queaño stressed that while some coral formations, which may eventually become limestones, were exposed in the uplifted areas, their long-term stability remains uncertain.

Meanwhile, Queaño warned that the effects of the earthquake are not limited to coastal communities, as ground movement and earthquake-induced landslides can also alter waterways, potentially creating new flood risks for communities.

“Kung may ilog na dating dumadaloy papuntang dagat pero yung coastal ay nag-uplift po siya, ang mangyayari sa natural adjustment na gagawin ng ilog ay hahanap siya ng pathway palabas. Kung ito ay dating pathway papuntang coast, puwede siyang lumiko. So pag lumiko po yan may community doon maaari siya maapektuhan (If there is a river that used to flow toward the sea but the coastal area is uplifting, the natural adjustment that the river will make is that it will find a pathway out. If this is a previous pathway to the coast, it might curve. So, if it changes path, a community there could be affected,” he said.

“So, any changes na nangyari sa (So any changes that happen in the) coastal area would have an effect on the upstream area,” he added.

Queaño explained that landslides caused by strong earthquakes can block rivers, creating temporary natural dams that may eventually collapse.

He said flash floods occur when the volume of landslide debris becomes too great.

The MGB, he said, is working closely with the Office of Civil Defense (OCD) and the local governments to monitor affected areas and provide hazard assessments. (PNA)