AN INTENSITY-9 earthquake will rattle Metro Manila and neighboring towns in case dormant faults within the metropolis tremble. With no formal earthquake drills despite active earth movement in the country, will the University withstand a big quake?

The Philippine Institute of Volcanology and Seimology (PHIVOLCS) forsees an earthquake in Metro Manila through the Marikina Fault. Located five kilometers east of Metro Manila, the fault is classified into the West Marikina Valley Fault (WVF) and the East Marikina Valley Fault.

A fault is a zone in between tectonic plates where blocks on the crust of the earth have moved past each other by sliding. The Philippines is in the middle of two opposing tectonic plates, making it prone to seismic activity. The recent eruptions of Mt. Kanlaon in Negros Oriental, Mt. Bulusan in Sorsogon, and Mt. Mayon in Albay indicate seismic activities in the country.

“The Marikina Fault has been inactive for so long, this means it has been building up for the last 400 years,” PHIVOLCS scientist Dr. Leonila Bautista told the Varsitarian. The long period of inactiity of the fault causes great concern to geologists since the longer period of latent time, the more threat it spells.Bautista said that similar to a human being’s surging emotions, the Marikina Fault can be highly destructive once it moves. The least effect would be an Inte nsity 9 earthquake.

Dr. Arthur Saldivar-Sali, a member of the Council of Engineering Consultants of the Philippines, said that an Intensity 9 earthquake can be compared to a bomb explosion under the ground.

As a precautionary measure, PHIVOLCS conducted an impact reduction study for Manila and listed 18 possible earthquake scenarios.

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According to the study, the top three faults that could cause the most destruction are the WVF, the Manila Trench and the Manila Bay fault.

The WVF that stretches from Marikina to Muntinlupa lies in a populated residential area, posing more damage and danger. A magnitude 7.2 earthquake could cause damage to 168,300 residential buildings and could kill 33,500 people. The 1990 Baguio earthquake that claimed 1,000 people registered 7.7 magnitude in the Richter scale.

On the other hand, movement along the Manila Trench will produce less damage and less casualties considering its location under the sea. Based on past earthquake records, the tsunamis in 1677 and 1863 were caused by earthquakes from the Manila Trench. The Manila Bay fault is also feared for its capacity to cause a tsunami.

“The reason for the study is to raise awareness on what may happen. We hope that by showing statistics based on actual facts, we can convince policy-making institutions to act before it’s too late,” Bautista said.

Tough Main Bldg.

Thomasians are assured that the UST Main Bldg. can at least endure an Intensity 9 earthquake caused by fault movements.

Claimed to be the first earthquake-proof structure in the country, the Main Bldg. endured four major earth- quakes in the last seven decades: 1937, 1968, 1970, and 1990. (see sidebar)

Designed in 1923 by Fr. Roque Ruaño, a renowned engineer who went to Japan to study earthquake-resistant structures, the Main Bldg. could be the last structure standing in case a big quake hits UST.

The Main Bldg. incorporates a seismic design and adopted the engineering standards of Japan which makes it earthquake-proof. Moreover, the building is divided into 40 units with four or six piers strongly tied together, with seismic gaps of an inch filled with loose cement, to accommodate any movement in case of earthquakes.

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According to architect Clarissa L. Avendaño, assistant director of the Museum of Arts and Sciences, the Main Bldg. deviates from the common rigid structures of other buildings.

Other UST buildings are not as earthquake-proof and their capacity to withstand strong earthquakes is uncertain. There are no studies what intensity of earthquake these buildings can endure.

“But all buildings of the University are connected in a ‘tie-beam’ system in which foundations are joined. Damage would be minimal in case of an earthquake as movements of the buildings would be in unison,” engineer Lawrence Pangan of Buildings and Ground (B&G) told the Varsitarian.

Pangan said that a building’s capacity to withstand earthquakes depends on the structural designer’s calculation. He said that structural engineers base their construction of buildings on the highest recorded earthquake magnitude in an area and makes the necessary adjustments on a building’s foundation. However, Pangan said that preventing higher than Intensity 9 earthquakes raises costs of construction.

Meanwhile, a different kind of construction technology was used in the Alfredo M. Velayo (AMV) College of Accountancy and the Tan Yankee Student Center buildings, among others.

“Pile-driving is used for the new buildings. This modern method installs foundations by drilling them, instead of hammering, to effectively resist forces like earth movement,” Pangan said.

As a rule, architect Magno Salde Jr. of Recio-Casas Architects, which designed the AMV College of Accountancy Bldg, said building designs should always comply with the Building Code of the Philippines. Soil testing and surveying the site locations should be done before any construction.

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“The structural design should not compromise the safety of people. Lighter materials are used to avoid too much weight for the foundation,” Salde said.

While the Main Bldg. is one of the most stable structures in Manila, surviving earthquakes in the past, other buildings may not be as sturdy. But even before the next quake proves their resilience, Thomasians should know the basics of surviving quake shocks. Jamaila S. Cahilig and Marie Jeanette P. Cordero

1 COMMENT

  1. Can someone tell me if Roque Ruano Building (Engineering Bldg.) can withstand a 7 or higher magnitude of earthquake?

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