Bu-lat-lat (boo-lat-lat) verb: to search, probe, investigate, inquire; to unearth facts
Vol. IV, No. 27 August 8 - 14, 2004 Quezon City, Philippines
One’ Is Possible But Metro Is Unprepared
AUBREY STA. CRUZ MAKILAN
Here’s something that the country’s national leaders should be bothered about: If a major earthquake were to hit Metro Manila today, the devastation would be so big even disaster response authorities cannot simply cope with it. And it even looks like disaster preparedness occupies a low priority among officials down to the municipal level.
Recent reports gathered by Bulatlat show that up to 35,000 residents of Metro Manila would die and up to three million others would need to be evacuated. In addition, some 175,000 buildings would be damaged. The pressure of collapsed buildings and the inability to rescue those who would be trapped inside would cause most of the deaths.
Distribution of active faults and trenches in the Philippines
With its current population of 10 million, Metropolitan Manila, which is composed of 13 cities and four municipalities, is densely populated with several clusters and districts having high-rise buildings close to each other. Investigations done by various disaster units and fire departments a few years ago found many buildings did not comply with construction standards and that these are prone not only to fires but also to damage by earthquakes of any scale.
One of the reports gathered by Bulatlat, the Metropolitan Manila Earthquake Impact Reduction Study (MMEIRS), cites “many research studies (indicating) that active phases of the (West) Valley Faults (formerly the Marikina Valley Faults) are approaching and that the estimated magnitude will be around 7 or more.” But MMEIRS also raised the possible intensity from 7 to even 9, which could be “devastating.”
The study projected the “big earthquake” to be “unlike any tragedy seen or imagined in Metro Manila.”
Asked for comment, however, a scientist-environmentalist theorized that such studies could be pressing the panic button now just to allow certain insurance companies to profit from a sudden surge of building insurance orders and the like.
MMEIRS, a Japan-funded study that was begun in August 2002, identified the West Valley Fault, which lies just northeast of Manila, as “the fault expected to cause the largest impact in the metropolis.” The West Valley Fault traverses Marikina town, Pasig going to Muntinlupa up to the south.
The Fault, other studies showed, caused at least two major earthquakes within the last 1,400 years. No earthquake is known to have taken place along the West Valley Fault after the 16th century. But based on the estimated return period of less than 500 years, the Fault is due to exhibit dangers this century – or even within the next few years, if the estimates of an official of the Philippine Institute of Volcanology and Seismology (Phivolcs) are valid.
Dr. Norman Tungol of Phivolcs’ Geology, Geophysics, Research and Development Division (GGRDD) estimated the Fault’s movement of recurrence at 200-400 years and based on this, he told Bulatlat, it is due for another movement.
Tungol said however that since studies have a big margin of error, this projection “could be within the next few years, (or) few tens of years.” He also said that even if there is no need for the people to panic because there is no timetable yet, “dapat mag-prepare because it’s inevitable.”
He confirmed that an earthquake with intensity 8 or 9 could be expected in the Valley Fault with a possible magnitude of 7.2 because of the lengthy fault.
Another Phivolcs scientist, Dr. Elena Bautista, noted however that the MMEIRS study found no pattern for the frequency of earthquakes occurring in the West Valley Fault.
A noted engineer, Dr. Arthur Saldivar-Sali, saw MMEIRS’ assertion that “active phases of the Valley Faults are approaching” as vague. He noted that the study, which he admits he has never seen, was apparently based on “deterministic analysis” which focuses on the characteristics of the movement of a fault and can be a prejudgment based on studies done or merely on gut feel that has no scientific basis at all.
Saldivar-Sali is a member of the Council of Engineering Consultants of the Philippines (Cecophil), a group of corporations and companies doing civil engineering designs and foundations.
Saldivar-Sali, a former UP professor who is also now with the Geo-Technica Consultancy Group, told Bulatlat that he tends to believe in the “probability analysis” of former Phivolcs Director Raymundo Punongbayan. Shortly after the Mt. Pinatubo eruption in 1991, Punongbayan told of a higher probability of a major earthquake on the Valley Fault based on its rare movements. Since lesser energy is released in the friction of rocks, more energy is stored, like a rubber band, preparing for a big snap.
The higher the percentage of the probability of an earthquake, the dangerous it would be, Saldivar-Sali said.
Punongbayan also cited the danger of building anything five kms near the fault. The director’s warning caused alarm among the business community and Marikina local officials asked that the fault be renamed “West Valley Fault” instead.
In layman’s terms, a magnitude of 7.2 can be compared to a bomb explosion, Saldivar-Sali said. In exponential form of 10, a magnitude of 1 is equivalent to one ton (1 x 100), magnitude 2 to 10 tons (2 x 101), 3 to 300 tons (3 x 102), and so on. A 7.2 magnitude if multiplied to 106 is equivalent to 7.2 million tons of bomb explosion.
MMEIRS actually aimed to design a master plan for earthquake impact reduction in Metro Manila leading to the holding of training seminars on earthquake preparedness. Funded by the Japan International Cooperation Agency (JICA-Philippines), the study was supported by the Metropolitan Manila Development Authority (MMDA), the Department of Science and Technology (DoST), Phivolcs and JICA contractors Pacific Consultants International, Oyo Corporation, and Pasco Corporation.
Scientists from Phivolcs, the University of the Philippines as well as from Japan participated in the study. Due for completion last March, the report is being finalized in Japan, according to Cora Macasieb, Special Operations Officer II and acting division chief of the Directorate for Special Operations of the Metropolitan Manila Disaster Coordinating Council (MMDCC).
Separate studies on earthquake are also being done in cooperation with China, Japan and the United Nations Development Program (UNDP).
Among others, three areas were tested under the MMEIRS study: Mataas na Lupa in Malate, Manila; Ugong, Pasig; and Cupang, Marikina. Studied were Metro Manila’s three fault lines, namely, the West Valley Fault, the Manila Trench and Manila Bay.
Analyzed were the areas’ earthquake history, length of the fault and vulnerability to earthquake. Damage scenarios and estimates of costs of destruction were also done.
The seismic intensity generated by the West Valley Fault earthquake and the damage felt in an area varied from place to place. The intensity may range from 7 in Quezon City, almost 8 and 9 alongside Marikina River and Manila Bay, and 8 at west of Metropolitan Manila and 7 at other areas. Based on the Phivolcs Earthquake Intensity Scale (PEIS), intensity 7 is “destructive,” while 8 and 9 are “very destructive” and “devastating,” respectively.
Aside from the estimated death toll, the West Valley Fault earthquake would cause injuries to 118,200 persons, the study reveals. MMDC’s Macasieb said that the death toll would rise if the earthquake occurs during office hours where most of the people are working inside buildings including those who would come from the province to process various papers in the metropolis.
The number of buildings expected to be destroyed by the Manila Trench earthquake would reach about 5,000 while 16,000 for the Manila Bay fault. The West Valley Fault earthquake will cause the collapse of buildings in northeastern Quezon City, western Marikina, eastern Pasig, Muntinlupa-Laguna Bay and Mandaluyong-Makati. Evacuation would be difficult in the metropolis’ fringes particularly in the north, Taguig and Las Piñas, the MMEIRS study also found.
Residential buildings around the Malacañang in Manila and the House of Representatives in Quezon City would be severely damaged. Other infrastructures such as bridges and power posts will also be destroyed.
The danger of spreading fire to the Malacañang presidential office is not ruled. Liquefaction around the House area might take place. Even the MMDA building would be severely damaged, the study adds.
Collapses would lead to electricity short circuit, petroleum and LPG leakages from storage tanks, among others, that would cause fire. Areas highly vulnerable to fire would be Valenzuela, Caloocan, and south of Quezon City west intersection.
Damages to the Angat reservoir and water purification plant would likely happen, causing a long-term stoppage in water supply. Public transportation facilities such as airport runways would be closed, leaving only helicopters available for operations. Ports in the North and South harbors would be damaged and tilted by liquefaction, making these inaccessible for loading and unloading. Damages would likely be expected on roads and bridges.
Including victims of fires and liquefaction caused by the earthquake, the study estimates the number of refugees or evacuees at three million. The figure would include 1.3 million persons who would be uprooted from their homes if the aftershock would last about seven days.
After liquefaction, there would be a possible regional separation. The western part of Metro Manila would be isolated from other parts of the metropolis. The same thing would happen to the northern and southern parts due to building collapse especially in the area intersecting Makati and Mandaluyong. Meanwhile, all road networks running east-west that are on the fault would be broken. Bulatlat
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