Nonexistent geological expertise
A friend recently furnished me a copy of “Metro Manila Earthquake Vulnerability Assessment November 2014,” which was produced by Pacific Strategies & Assessments (PSA Group).
PSA Group is led by a New Zealander, two gentlemen from the United Kingdom, an Australian, and an American who is its Philippine director. Judging from its website (www.psagroup.com), its usual clients are multinational companies.
Its expertise seems to be in law enforcement and security, but its geological expertise seems nonexistent, as represented by the geological content of the document. Any sophomore undergraduate in the National Institute of Geological Sciences (NIGS) at the University of the Philippines Diliman would have a far superior grasp of earthquake hazards.
Some excerpts from the PSA document:
Page 3 conflates the “Pacific Ring of Fire” and Pacific Seismic Belt. The first refers to volcanism, the second to earthquakes. Although causally related, they are not identical.
Page 3 also calls “the ridge in the mid-Atlantic Ocean” the “third” seismic belt. Actually, the Mid-Atlantic Ridge is only a limited part of the Mid-Oceanic Ridge, the Earth’s longest, interconnected mountain system with branches in all the oceans.
Page 5: “Typically, when two plates collide a major earthquake will be felt in the nearby land mass. When the collision is under a seabed that is relatively far from a land mass, it creates a seaquake or tsunami, which nonetheless can affect the nearest land mass.”
Actually, any single plate collision occurs over millions of years, not only when a single earthquake occurs. And destructive tsunamis can be propagated across entire oceans.
Page 8 betrays unfamiliarity with or lack of attention to Philippine geography, misspelling Siquijor as “Siguijor.”
Page 11, discussing the 1991 Pinatubo eruption, says: “Typhoon Diding, which occurred immediately after the eruption, scattering water-soaked ash over a very large area and causing massive mudflows.”
Our NIGS sophomore would correctly tell us that Diding came during the paroxysmal eruption on June 15, 1991, that the eruption continued for months afterward, and that the lahars during the eruption and for years afterward were not “mudflows” but were slurries of water and eruption debris, largely sand, gravel and boulders with next to no mud content.
My favorite part of the document, for its unintended humorous content, is on Page 13, discussing liquefaction:
“A closer evaluation of Metro Manila soil composition reveals that the region is dominated by quatemay allurium (Marikina, Pasig, Pateros, Taguig, Manila, Caloocan, Malabon, Navotas and parts of Makati, Valenzuela, Pasay and Parañaque), tuff and tuffaceious sediment (San Juan, Mandaluyong and parts of Quezon [City], Makati, Pasay and Parañaque), and pyroclastic flow deposit adobe (parts of Quezon [City], Pasig, Caloocan, Taguig and Muntinlupa).
“• Quatemay allurium is a mixture of clay, silt and gravel that is generally loose and not cemented together into solid rock. While these grounds are suitable for building foundations, they typically require compaction. This sediment is not suitable for construction of big infrastructures and buildings.
“• Tuff and tuffaceious sediment is a mixture of volcanic rock and mineral fragments. These grounds are generally suitable for foundations when well-drained and confined.
“• Pyrodastic flow deposit adobe is a mixture of sun-dried clay, rock, gravel and sand which is often mixed with straw or grass. While these grounds are suitable for foundations when well-drained and confined, they may require compaction.”
Here are my comments:
- “Quatemay” is misspelled “Quaternary,” where the “r” and the “n” were merged into an “m.” Quaternary must always be capitalized.
- “Allurium” is a misspelling for “alluvium.”
- “Tuffaceious” is a misspelling for “tuffaceous.”
- “Pyrodastic” is a misspelling for “pyroclastic,” where the “c” and the “l” were merged into a “d.”
- Most amusing is the characterization of “Pyrodastic flow deposit adobe.” Here, “adobe” is a Philippine colloquialism for pyroclastic-flow deposits, misapplied by the Spaniards from their experience in the Americas, where “adobe” was bricks of sun-dried clay mixed with grass. Pyroclastic-flow deposits, also called tuffs, are very well consolidated, have very low porosity, are hardly compactible, and thus are good building materials. These rocks are the firm foundation on which Batasang Pambansa and UP Diliman were built.
The shoddy scholarly quality of the document includes its lack of proper attribution of its sources of information. However, it is itself copyrighted!
Any organization seeking advice about the vulnerability of Metro Manila to earthquakes would be wise to refer instead, at no cost, to the excellent 2004 study, “Earthquake Impact Reduction Study for Metropolitan Manila, Republic of the Philippines,” which was conducted jointly by the Japan International Cooperation Agency, Metropolitan Manila Development Authority, and Philippine Institute of Volcanology and Seismology.
Why should any foreign or multinational entity seek advice about the Philippines from other than Filipino experts? Unfortunately, an attitude prevalent among all too many Filipinos is that foreigners are somehow more to be trusted. That calumny is all too often transmitted to naive foreigners.
Kelvin S. Rodolfo is professor emeritus of the Department of Earth and Environmental Sciences at the University of Illinois at Chicago, and corresponding member of the Philippine National Academy of Science and Technology.
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