(Editor’s Note: This story was first published by Newsbreak.)
On the afternoon that typhoon Hambalos was leaving the country the other week, two geologists from the Southern Tagalog office of the Mines and Geosciences Bureau (MGB) rushed to a private subdivision in San Pedro, Laguna. Upon the request of the housing regulatory agency and the residents, they were to inspect houses whose floors had sunk by nearly a foot, causing cracks on walls and misaligning doors and window jambs.
Chief geologist Elmer Billedo’s initial interpretation of the incident was that the underground of a particular street had been saturated by water and thus softened. The street, where at least seven houses had been rendered uninhabitable, is sitting on what used to be a creek which the developer had filled with earth to maximize space for its project. Over the years, diverted water had managed to seep back to the artificial ground. Here was a potential Cherry Hills happening at a much slower pace.
A week before, another team from MGB Region 4 checked on a quarry site in Barangay San Rafael in Rodriguez, Rizal, where a huge rock had been left hanging from the steep slopes since the government was forced to abandon a road-widening project in the area.
In a yet-to-be published report, the team advises residents around the quarry site to “immediately evacuate” because an earthquake or heavy rainfall could send the hanging rock tumbling down on the community anytime.
The rainy season—with the threats of flashfloods, landslides, and ground sinking that it brings—is the busiest for geologists, Billedo notes. Unfortunately, assessing the natural hazards in an area only when danger unfolds or has occurred is not what geologists should be doing mostly in a country as disaster-prone as the Philippines.
The natural hazards common in the Philippines are typhoons, such as the three consecutive ones that claimed more than 1,000 lives in Metro Manila in November 1995; flashfloods, such as the one the killed 8,000 persons in Ormoc City in November 1991; landslides due to rainfall, such as the one that killed 58 residents in a private subdivision in Antipolo City in 1999; earthquakes, such as the one that killed nearly 1,000 persons in Baguio City and neighboring cities in July 1990; and volcanic eruptions, such as the fury of Mt. Pinatubo that killed 800 persons in Zambales in June 1991.
Sitting on the planet’s typhoon, volcanic, and earthquake belt, the Philippines, ideally, should be keeping its geologists busy with preventive surveys and assessments—before local governments draft their land use plans, before companies develop subdivisions or resorts, before multinationals begin mining operations, and before engineers break ground for high-rise buildings, shopping centers, or universities.
However, a perennial shortage of funds and technical experts has prevented the Philippines from even coming close to the ideal state of geologic survey and research.
Newsbreak learned that the MGB has done the “composite geologic hazard susceptibility maps” of only Metro Manila out of 16 regions, four of 79 provinces, and seven of 83 cities. Target areas for mapping next year are yet to be identified.
The hazard maps indicate what specific areas in a city or province are especially susceptible to specific types of geologic “occurrences,” as technical experts prefer to call them. In other words, the maps identify the disaster-prone spots.
Maps That Warn
The hazard maps of Metro Manila, Baguio City, Butuan City, and Zamboanga City are already with the local government units (LGUs). To be released any time in August are the hazard maps of the provinces of Cavite, Mindoro Oriental, and Surigao del Norte, and of the cities of Olongapo and Davao. By October, the maps of Tuguegarao City and Cagayan de Oro City should be out.
The map of Metro Manila indicates which cities are expected to be heavily flooded come rainy days, or which cities may experience ground liquefaction should an earthquake hit.
On the other hand, the map of Baguio City shows that Teachers’ Camp and Camp John Hay Club are high-risk areas for landslides, that Mines View Park is located near a fault line, and that Quirino Hill, a squatter relocation site, is sitting on a sinkhole or a vacuum created when rainwater dissolves the limestone underground.
The map of Butuan, meanwhile, shows that the whole city is susceptible to tidal floods, owing to its location along the banks of the Agusan River. The city proper and the low-lying barangays are standing on mostly sandy sediments, making the city vulnerable to liquefaction during an earthquake.
“These maps are not produced to tell you not to live there; they tell you that extra precautions are needed if you want to live there,” says Claro Manipon, supervising geologist of the geographic information systems (GIS) section at the MGB’s central office.
The MGB normally avoids releasing the hazard maps to parties other than local government units (LGUs) because it fears that unscrupulous developers or brokers might use the findings to jack up the real estate rates in low-risk areas, or that investors might withdraw from high-risk areas.
Funds and Geologists
The caution apparently stems from the experience of Baguio where the local council admittedly agonized over making public the assessment given by the MGB in 1998. The hazard zones identified by the bureau were host to commercial establishments and multimillion-peso houses, and made city officials worried that the findings would slash real estate values by at least half.
Manipon says, however, that LGUs should look at the hazard maps in a constructive way: “The job of the LGUs is to refer to the susceptibility maps so they’ll know what requirements to impose on those applying for permits for developments or constructions. The maps should serve as a warning to planners and engineers where they need to do extra work.”
For instance, one of the features of the hazard map of Davao City is the identification of areas where the ground will shake more vigorously and lose strength more quickly than others during an earthquake. The information gives engineers an idea what kind of design and strength of materials the structures in the area should possess so these can withstand an earthquake with a magnitude of 7. Already, the city government has temporarily suspended the construction of a sports complex in Barangay Maa while verifying reports that the site is a few meters away from a fault line.
If the hazard maps can determine such life-and-death matters, then why is government doing the hazard mapping only now, and at such a slow pace?
Antonio Apostol, officer in charge of the MGB’s geological survey section, says that the bureau will need a budget of P90 million to map the entire Philippines for geologic hazards, conduct detailed and site-specific ground work, do laboratory tests, and write up comprehensive assessments and recommendations. To complete the work in one year, 200 to 300 geologists should be employed in the geo-hazard mapping program full-time.
Right now, MGB’s central office has a contingent of only 40 geologists for the hazard mapping program, including those doing the laboratory work. The program has a P1-million-a-year allocation. The MGB’s regional offices have a combined budget of P6 million a year.
“Then there is the reality that geohazard events should take a back seat to El Niño, landfill sites assessment, groundwater resources assessments, and other services that are equally important,” Apostol says. So what the MGB does is to prioritize densely populated and economic growth areas for its hazard mapping program, he says.
Manipon says that to come up with a composite map, the following should be available: a geologic map, satellite images, a vegetation or soil map, aerial photographs, a topographic map, records on earthquake and landslide occurrences, river discharge measurements, and drilling data, among others. Most LGUs, he says, have only the first three requirements.
According to Manipon, the availability of a map of the locality’s geologic features already accounts for 50 percent of the hazard mapping work. However, the MGB is a long way from finishing the geologic mapping of the entire country. Geologists in the bureau have divided the Philippines into 977 geologic quadrangles, with a quadrangle equivalent to 40,000 hectares. An inventory made available to Newsbreak shows that MGB still has to work on 574 quadrangles in at least 27 provinces, mostly in Mindanao.
The GIS does the regional mapping or surveys that cover entire cities or provinces. Detailed geologic studies on specific sites within those cities or provinces are conducted by the MGB’s urban geology section and the regional offices.
Simply put, the GIS, for example, scans Cavite for its geological hazards “like looking at the area from an airplane,” Manipon says. But since such mapping, as structural geologist Mario Aurelio puts it, “is like traveling from Quezon City to Makati in five seconds—you can’t observe the details,” verification work should be done on the ground. That’s when the urban geology section or the Region 4 office will then study, say, the rock samples and vegetation in Trece Martires or measure the river discharge in Kawit to verify from the ground the susceptibility of localities to landslides or tidal floods.
“A lot of people are telling us that this geohazard mapping is a bit too late because the communities are already there, and we cannot expect them to abandon the area because of our findings. But mitigating measures are available [for developed areas], and they need the information on areas they would want to develop in the future,” says Aurelio, chief of the MGB’s urban geology section.
He says that developers and engineers actually often consider government geologists as “a curse” when the latter come inspecting project sites and “recommend” changes in structural requirements, and therefore additional expenses, in the face of uncovered geologic risks in the area.
But since the government makes passing geologic assessments only optional for developers to get the environmental clearance certificate for their projects, many recommendations by the MGB specialists have gone unheeded.
It’s tragic, Aurelio says, that Filipinos are in the habit of waiting for catastrophes before realizing the necessity of knowing the geologic hazards before building in an area. It took the Cherry Hills tragedy before then Environment Secretary Antonio Cerilles directed the MGB to come up with the comprehensive hazard maps.
Indeed, the Philippines recently ranked fourth on the International Red Cross and Red Crescent Societies’ list of countries with the most number of casualties or injuries from calamities over the past decade. Local Red Cross governor Dante Liban correctly pointed out that the disasters, whether natural or man-made, were the result of government negligence. – Rappler.com