While much focus remains on the looming “Big One” – the projected magnitude 7.2 earthquake along the West Valley Fault that threatens Metro Manila – a potentially even more destructive seismic risk is poised over the Visayas. Negros Island faces an imminent threat from the Negros Trench, a geological feature capable of generating a colossal magnitude 8.2 earthquake, according to the Department of Science and Technology-Philippine Institute of Volcanology and Seismology (DOST-Phivolcs).
Phivolcs Director Teresito Bacolcol, during a visit to Bacolod City, underscored the gravity of this threat. The Negros Trench, a $400$-kilometer-long subduction zone, is situated northeast of the Sulu Trench, west of the Negros Island Region, and lies within the Sunda Plate. This proximity means that a powerful quake here could severely rock the entire Negros Island.
Tsunami Warning: Minutes to Act
The danger doesn’t end with ground shaking. A shallow quake of this magnitude in the Negros Trench poses a significant tsunami risk. Such an event could rapidly inundate the western coastlines of Negros and Panay, with effects potentially reaching as far as Palawan and Zamboanga. The critical concern is the speed of impact: a tsunami could strike within five minutes of the main earthquake.
Bacolcol’s urgent advice is clear: residents living near the sea must be aware of the natural signs of a tsunami and prioritize immediate escape. He stressed that a moment’s hesitation, such as stopping to take photos, could be fatal. “People should immediately run for higher ground,” he advised.
Recognizing the Signs
Recognizing these natural warning signs is paramount for survival. Just one of these indicators is enough to signal an imminent tsunami:
- Strong, prolonged ground shaking that makes it difficult or impossible to stand.
- A sudden, unusual drop in sea level, exposing the seabed.
- A loud, roaring sound emanates from the sea.
While preparations for the Metro Manila ‘Big One’ are essential, the vulnerability of other areas, particularly Negros Island, to the Negros Trench demands equal attention and preparedness. Understanding the unique risks and being ready to respond to natural warning signs are vital steps in mitigating potential catastrophe across the archipelago.