Thursday, August 18, 2011

West Valley Fault System: It's closer than we think

General Elmo San Diego (Ret), Head of the Department of Public Order and Safety of the Quezon City Government, did not mince words about the grave danger posed by the West Valley Fault System that runs underneath the streets, houses, and backyards of Metro Manila residents. The Fault is capable of causing an Intensity 7 earthquake. Even hospitals are expected to crumble to the ground and the open spaces of QC would be reserved for emergencies. It would be a terrible day for the Head of his department when that day comes, he said.

Gen Elmo San Diego, Head of the Department of Public Order and Safety of Quezon City, spoke in front of Rotarians on Aug 16, 2011

San Diego spoke to around 50 Rotarians on Aug 16, 2011 about the burning issues that confronted his department. This was on the occasion of the Joint Club Meeting among the Rotary Club of Sto Domingo QC, Rotary Club of Kamuning, Rotary Club of Dilman Central, Rotary Club of Kamuning East and the Rotary Club of St. Ignatius. San Diego comes from the Rotary Club of Kamuning.

The West Valley Fault System (formerly called Marikina Fault Line) stretches from Montalban, Rizal to Sta Rosa Laguna. It cuts through the eastern fringes of Quezon City, Pasig City, Makati and Taguig
Image from Pinoy Money Talk

During the Joint Meeting, San Diego spoke about how his department was addressing colorum tricycles, tri-sikad on the streets, apprehending and fining traffic violators and parking problems in the city.

Then he zoomed in on the West Valley Fault System.

San Diego’s statement echoed a similar message by Philvolcs Director Renato Solidum Jr., who warned the public about this in 2009:

MANILA - Some 38% to 40% of Metro Manila's residential and mid-rise buildings, as well as 14% of the area's high-rise buildings, could be destroyed in the event of a 7.2 magnitude earthquake, which could happen anytime between now and the next 400 years, the chief of the Philippine Institute of Volcanology and Seismology said Wednesday.
Phivolcs Director Renato Solidum Jr. issued the warning during Wednesday's Senate hearing on climate change, which was chaired by Sen. Loren Legarda and Sen. Rodolfo Biazon. Source:

The West Valley Fault System
Click on the image to enlarge
The thick line in the accompanying map outlines where the West Valley Fault System traverses. It "hits" the following subdivisions: Loyola, Cinco Hermanos, Don Juan, Industrial Valley, Camp Atienza, St. Ignatius Village, White Plains (eastern side), and Greenmeadows. In fact, the fault line stretches all the way to Sta Rosa, Laguna and the fringes of Taal Lake.

According to the US Geological Survey, the western side of the West Valley Fault System pushes northwards and the eastern side pushes southwards. A slip can cause an earthquake with an Intensity 7.3 to 7.7. Analysts estimate this scenario to happen once every 200-400 years.

Apparently, this fault was discovered as early as the 1920s, during the American occupation. When Manuel L. Quezon administered the city before the war, he wanted the West Valley Fault System to be established as an elongated park. It would be planted with trees on either side of the fault to prevent anyone from putting up a house close to or on top of the Fault. Apparently this plan was overtaken by war and his eventual death in the US mainland.

Today, the fault line is hidden underneath the floors of houses in plush subdivisions of Metro Manila.

San Diego realizes the implications of breaking this news to owners of the houses constructed on top or within 5 meters of either side of the fault. Yet he understands that it is his duty, no matter how unpopular, to inform these residents and advise them to vacate the houses immediately.

The grave danger is not limited to those along the fault line, San Diego emphasized. When an earthquake strikes, the whole land mass moves. Buildings several kilometers away from the Fault could still be devastated. Thus, it is the duty of everyone, not just those along the fault lines, to be prepared.

As citizens, what can we do under the imminent danger of this “act of God”? Prayer would certainly constitute part of our response. Preparedness is the other. A well-prepared citizenry may not save the whole city, but it would mean everything to every person that would receive a helping hand on that day that we pray would never come.

The Philippine Institute of Volcanology and Seismology offers educational trips to their premises, lectures, video documentaries and digital images to the public.

Click on the image above to see a more detailed reference of the active faults in the entire country. Image is from the PHILVOLCS Official Website

About P/Gen Elmo San Diego (Ret.)

P/General (Chief Superintendent) Elmo San Diego was born on May 11, 1954 in Marikina City to Ernesto S. San Diego and Carmen R. de Guzman. He is married to Karangalan Bumanlag, a businesswoman. They have 3 daughters, Carmencita, Catherine, Corazon and a son, Elmo Jr..

He finished his primary studies at Cubao Elementary School, his high school education at Quirino High School and took up AB Political Science at Far Eastern University where he graduated in 1974.

He entered the Police Service in June 22, 1975 as Patrolman first class. He later enrolled at the Philippine National Police Academy in 1979 and graduated in 1981 with a degree of Bachelor of Science in Public Safety and a rank of lieutenant.

As a police officer, he continued his quest for knowledge at PCU and finished his Masters in Management in 1994, and again graduated MA Criminology in 1995 at PCCR and finally achieved his PhD in Criminology in 1997 also at PCCR. He rose from the ranks and held several key positions at the Philippine National Police. In between his police career, he attended numerous seminars and trainings. He also trained and taught younger officers, and was promoted to Chief Superintendent (General) in 2010 when he was the Chief of Police of Quezon City during the term of Mayor Belmonte.

After his retirement, he was appointed by Mayor Herbert Bautista as the Chief of the Dept. of Public Order and Safety of Quezon City.

Posted By:
Marvin Macatol, Silver President (2011-2012)
Rotary Club of Sto Domingo QC

- - -


  1. Active Faults and Trenches in the Philippines | Philippine Institute of Volcanology and Seismology
  2. Multiple large earthquakes in the past 1500 years on a fault in metropolitan Manila, The Philippines
  3. Neotectonics of the Marikina Valley fault system (MVFS) and tectonic framework of structures in northern and central Luzon, Philippines
Other sources:
  1. Wikipedia: Valley Fault System
  2. Yahoo Answers: Where can i find the map of marikina valley fault line?
  3. Discussion: Valley Fault Line formerly known as the Marikina Fault Line
  4. Where is the Marikina fault line?

1 comment:

  1. Triangle of Life: Earthquake Tips