Lessons from ‘Bopha,’ aka ‘Pablo’

Late in November to early December 2012, Typhoon “Bopha” known in the Philippines as Typhoon “Pablo,” made landfall three times as it passed through northern Mindanao, Central Visayas and Palawan, affecting over 6.2 million people.

At the time, it was the strongest tropical cyclone to ever hit Mindanao, which had been rarely visited by typhoons before then. A total of 1,067 deaths were recorded, with 834 listed as missing. Aside from the Philippines, Bopha also devastated the Pacific islands of Palau and Micronesia.

A paper, “The December 2012 Mayo River debris flow triggered by Super Typhoon Bopha in Mindanao, Philippines: Lessons learned and questions raised,” published in the journal of Natural Hazards and Earth Systems Sciences, posits that the high fatality rate was caused in part by lack of preparedness and swift action on the part of national and local authorities.

The paper is authored by Kelvin S. Rodolfo with coauthors A. Mahar F. Lagmay, Rodrigo C. Eco, Tatum Miko L. Herrera, Jerico E. Mendoza, Likha G. Minimo, and Joy T. Santiago. In a note, Rodolfo says the authors “took much effort to publish [this paper] because we insisted on being holistic and understandable across many disciplines.” Rodolfo, who first burst into prominence as an authority on lahar flows in the wake of the 1991 Mount Pinatubo eruption, is professor emeritus of earth and environmental sciences at the University of Illinois at Chicago, and is a senior research fellow of the Manila Observatory.

In only seven hours, the paper says, Bopha delivered more than 120 mm of rain to the Mayo River watershed in Compostela Valley, “generating a debris flow that deposited a dry volume of 30 million cubic meters, the world’s seventh largest of record.” The debris flow “devastated” the village of Andap in the town of New Bataan which lay in its path, where 566 (about half of the total number of dead caused by Bopha) inhabitants were killed.

Like lahar in the 1990s, “debris flow” is a rarely mentioned threat that the authors describe as “among the most lethal of natural hazards.” “They are remarkably poorly recognized in the Philippines, especially in Mindanao, which lies in the southern fringe of the western North Pacific typhoon track and thus has been infrequently visited by typhoons and debris flows.”

It was this unfamiliarity with debris flows, as well as with typhoons in general, that “exacerbated the loss of life” in the towns and settlements in its path. “Every health center or school that collapses in an earthquake and every road or bridge that is washed away in a flood began as development activities,” the authors say, citing a UNDP report.

“The people and government authorities who established New Bataan and Andap in 1968 did not know that they were building on ancient debris-flow deposits, and they were unaware of the hazardous process that produced the deposits. The lack of awareness about debris flows persisted until Bopha approached, when many people were advised to seek refuge from flooding on high ground in Andap.” Even after the disaster, local authorities seemed unaware of the real nature of the hazard. Government personnel, it was pointed out, “initially designated to explain the tragedy and select relocation sites treated it as a ‘flash flood,’ not as debris flow.”

Photos of Andap taken after Bopha show a steep mountainside piled high with the remnants of destroyed houses, uprooted trees, gigantic boulders and the carcasses of livestock.

Why would folk choose to locate their town on a mountainside? Explain the authors: “The rapid growth of the Philippine population provided the impetus for the establishment of New Bataan and Andap in the late 1960s,” with the populace largely unaware of the flimsy ground beneath their homes and feet.

Meanwhile, write the authors, “the population continues to expand into more areas susceptible to natural hazards. Drawing upon Andap and numerous other recent disasters, the government must more rigorously assess the hazards posed to new settlement sites and infrastructure.”