Latest Stories

Metro showing signs of new fault?

Experts split; DOST funds study

By ,

SIGNS Architect Paulo Alcazaren points out areas (encircled) in and around Metro Manila where subsidence had been mapped and the line where a possible fault line has developed, during a media presentation in San Juan on Wednesday. He is part of a coalition that warns that Manila Bay reclamation projects are vulnerable to earthquakes. NATHANIEL MELICAN

The Department of Science and Technology (DOST) has started studying a renowned geologist’s initial findings which hint at the formation of a new fault line that cuts through Quezon City and intersects with the Marikina Valley Fault Line.

According to Dr. Kelvin Rodolfo whose findings prompted the DOST to conduct the follow-up study, a team led by geological expert Dr. Mahar Lagmay was verifying his theory.

At a press conference the other day called by the Save our Seas-Manila Bay group which is opposed to a proposed reclamation project on the bay, Rodolfo said he stumbled upon what initially appeared to be a new fault line while observing land subsidence patterns due to ground     water extraction in Metro Manila between 2003 and 2006.

“We used a very high-tech satellite tool called Permanent Scatter Interferometric Synthetic Aperture Radar. In short, the satellite takes images of the earth over time and combines it to show subsidence through various colors,” he added.

The images collected of Metro Manila and neighboring provinces showed yellow to red patches in the towns of Guiguinto, Malolos, Marilao and Obando in Bulacan; Caloocan, Malabon, Navotas, Valenzuela, Manila, parts of Quezon City, Taguig, Pateros, Las Piñas, Muntinlupa; and portions of the provinces of Cavite and Laguna.

43.8 mm per year

This, Rodolfo said, meant that the land was sinking, primarily because of too much groundwater extraction. It must be recalled that some areas in Camanava (Caloocan, Malabon, Navotas and Valenzuela) sank at the rate of 43.8 millimeters per year between 2003 and 2006.

However, a noticeable part of the map, south of where the heaviest subsidence was observed, was in dark blue and this meant that the area was rising at around 19.2 millimeters per year during the same period.

“You notice that on one side, there seems to be small increases, meaning tectonics is raising the ground but groundwater pumping is counteracting it. But in areas south of the line, it’s definitely going up. What it’s saying is we likely have a new fault which we just found in this study of land subsidence,” Rodolfo said.

However, he cautioned that much more work needs to be done before it can be confirmed as a fault.

“These pictures from the satellite are only half of the story. It’s only good when it can be verified through studies conducted on the ground,” he said.

“[Dr.] Mahar Lagmay and his staff are doing a study which is still ongoing and funded by the DOST,” he added.

Lagmay is the head of the DOST’s multibillion-peso Project Noah (Nationwide Operational Assessment of Hazards), a two-year flood forecasting and warning system. A University of the Philippines (UP) professor, he earned his doctorate in Earth Sciences from the University of Cambridge.

Rodolfo, on the other hand, is a professor emeritus of the University of Illinois, Chicago and an adjunct professor of the UP National Institute of Geological Sciences. He earned his doctorate in geological sciences at the University of Southern California. He is also a consultant of Project Noah.

When contacted by the Inquirer for comment, the director of the Philippine Institute of Volcanology and Seismology (Phivolcs) said that there was not enough evidence for now to support Rodolfo’s theory.

No proof for now, says Phivolcs

“We [saw] the same thing they [did] but we did not interpret it the same way. We didn’t find any evidence of a new fault,” Renato Solidum said.

According to him, a very careful evaluation of data was required for any such conclusions to be made. Solidum noted that the presence of the West Valley Fault was “very obvious” to seismologists unlike the supposed new fault.

In determining if there really was a new fault in Metro Manila, he said the next question to ask would be if this fault was active, and if active, whether it could cause a major earthquake.

Metro Manila, Solidum noted, was both a plateau and a delta, the former being a buildup of sturdy rocks, and the latter referring to a place where sand is deposited.

“This means there’s soft ground and hard ground. So we have to be certain. We have to be able to explain if the ground is subsiding or uplifting,” he said.

“If indeed there’s a major fault, it must be associated with a major earthquake. Some people are confused if you say there is a fault because you have to ask, ‘Is it active?’” Solidum added.

He said that Phivolcs scientists had also observed subsidence in a “central part of Metro Manila” applying the same technology Rodolfo used but they did not make the same inferences.

A 2000 seismic hazard assessment of Metro Manila published in the Bulletin of Seismological Society of America showed that Metro Manila had been “heavily damaged by earthquakes at least six times in the past 400 years, but the specific sources for the earthquakes are uncertain.”

Scientists believe the MarikinaValley Fault System, or the Valley Fault System that runs north to south along the west and east edges of the Marikina Valley, is the likely source. It has two segments, the East Valley Fault and the West Valley Fault.

There are fears that the West Valley Fault could make a major movement at any time. A risk assessment study funded by the Japan International Cooperation Agency noted that the West Valley Fault had moved four times and generated strong earthquakes within the last 1,400 years.

Follow Us

Follow us on Facebook Follow on Twitter Follow on Twitter

Recent Stories:

Complete stories on our Digital Edition newsstand for tablets, netbooks and mobile phones; 14-issue free trial. About to step out? Get breaking alerts on your mobile.phone. Text ON INQ BREAKING to 4467, for Globe, Smart and Sun subscribers in the Philippines.

Tags: Camanava , Department of Science and Technology , DOST , Dr. Mahar Lagmay , Earthquake , Marikina Valley Fault Line

Copyright © 2014, .
To subscribe to the Philippine Daily Inquirer newspaper in the Philippines, call +63 2 896-6000 for Metro Manila and Metro Cebu or email your subscription request here.
Factual errors? Contact the Philippine Daily Inquirer's day desk. Believe this article violates journalistic ethics? Contact the Inquirer's Reader's Advocate. Or write The Readers' Advocate:
c/o Philippine Daily Inquirer Chino Roces Avenue corner Yague and Mascardo Streets, Makati City, Metro Manila, Philippines Or fax nos. +63 2 8974793 to 94
  1. Senator’s kickback from pork bigger than those of Enrile, Estrada, Revilla – Lacson
  2. 12 senators on Napoles ‘pork’ list, says Lacson
  3. Napoles spills beans on Enrile, Estrada, Revilla – De Lima
  4. Sandigan junks Marcos family claim to Paoay property
  5. Delfin Lee: Blame Pag-Ibig, not me
  6. Cedric Lee’s cohort flies out of PH despite look-out order – De Lima
  7. San Juan cops fail to arrest Cedric Lee
  8. Maid confesses in killing of 2 and stabbing of employer in Laguna
  9. More ‘Yolanda’ bodies found
  10. Vitangcol to sue Czech envoy
  1. Napoles spills beans on Enrile, Estrada, Revilla – De Lima
  2. Gigi Reyes pins blame on aide
  3. Estrada: Gigi Reyes won’t testify vs JPE
  4. Bernice Lee arrested by NBI team
  5. Enrile chief aide back in PH ‘to face charges’
  6. ‘No real progress in PH if dynasties not dismantled’
  7. Suspect in Vhong Navarro’s mauling wants to turn state witness – De Lima
  8. Reckless driver endangered lives of Aquino, entourage–report
  9. More legal woes for Cedric Lee
  10. Henares on Pacquiao bashing: I did not start this
  1. KL confirms Malaysian Airlines Flight MH370 ended in Indian Ocean
  2. MRT passengers pass the hat for 6-year-old Ashley
  3. Rookie, lady cops lauded for quick response to MOA heist
  4. Malaysia averts another air tragedy; pilot lands troubled plane safely
  5. Revilla says he was joking; Lacson stands by his story
  6. Revilla ‘consulted’ Lacson on how he evaded arrest
  7. Cudia, dismissed for lying, got 99% in conduct
  8. Kim Henares needs a reprimand, says Cayetano
  9. Hammer-wielding robbers cause chaos at Philippines’ Mall of Asia
  10. Napoles spills beans on Enrile, Estrada, Revilla – De Lima


  • Camilla’s brother dies in US after head injury
  • Luisita farmers storm DAR compound
  • Trillanes, Ejercito confident they are not in Napoles’ list
  • Easterlies to prevail in Luzon, Visayas
  • Lacson eyes P106-B ‘Yolanda’ rehab masterplan
  • Sports

  • Mixers trim Aces; Painters repulse Bolts
  • Donaire junks Garcia as coach, taps father
  • ’Bye Ginebra: No heavy heart this time
  • UAAP board tackles new rules
  • Baguio climb to decide Le Tour de Filipinas
  • Lifestyle

  • Photos explore dynamics of youths’ sexual identity
  • 12th Philippine Food Expo set at the World Trade Center
  • No tourist draw, Malang the croc will remain wild
  • The best flavors of summer in one bite, and more
  • Homemade yogurt, bread blended with pizza, even ramen
  • Entertainment

  • Sony developing live-action Barbie comedy
  • California court won’t review Jackson doctor case
  • Return of ‘Ibong Adarna’
  • Practical Phytos plans his future
  • In love … with acting
  • Business

  • Facebook profits triple as mobile soars
  • Insular Honors Sales Performers at Testimonial Rites
  • Apple increases stock buyback, will split stock
  • Cost-recovery provisions for affected gencos urged
  • This time, BIR goes after florists
  • Technology

  • Top Traits of Digital Marketers
  • No truth to viral no-visa ‘chronicles’
  • ‘Unlimited’ Internet promos not really limitless; lawmakers call for probe
  • Viber releases new design for iPhone, comes to Blackberry 10 for the first time
  • Engineers create a world of difference
  • Opinion

  • Editorial cartoon, April 24, 2014
  • Talking to Janet
  • Respite
  • Bucket list
  • JPII in 1981: walking a tightrope
  • Global Nation

  • Filipinos in Middle East urged to get clearance before returning
  • PH seeks ‘clearer assurance’ from US
  • China and rivals sign naval pact to ease maritime tensions
  • What Went Before: Manila bus hostage crisis
  • Obama arrives in Tokyo, first stop of 4-nation tour
  • Marketplace