'New' earthquake fault discovered in Manila?

03/07/2013 07:34

Ridge under ManilaWhile studying movement patterns in the earth under Metro Manila, geologists have discovered a boundary or "ridge" —a possible fault line— between flood-prone subsiding areas and gradually rising areas in the metro.

However, Phivolcs said that there is no clear evidence of a "new" active fault line in Metro Manila.

On the morning of March 6, landscape architect and urban planner Paulo Alcazaren posted a photo on his Facebook page of Dr. Kelvin S. Rodolfo, Professor Emeritus of the Dept. of Earth & Environmental Sciences at the University of Illinois at Chicago, giving a talk on issues surrounding proposed reclamation efforts in Manila Bay.

Rodolfo's talk touched on a geologic survey map of Manila, which indicated areas that are subsiding —and are therefore prone to floods— as well as other areas of the metro that are gradually rising.

Accidental discovery

However, what caught Alcazaren's and other observers' eyes was that there seemed to be a dividing "ridge" separating these subsiding and rising areas.

"Subsidence on one side leads to greater flood risks, but what could be of greater risk is the presence of not one but two major fault lines in the metro —and the scenario of greater loss of lives in a major earthquake," Alcazaren said in his Facebook post.

"Nasilip nila ito accidentally. Pinag-aaralan nila yung subsidence ng Metro Manila. When they were getting data, the rate of subsidence of the northwest side of the metro was different from the southwest side," Alcazaren further explained in a phone interview.

However, Alcazaren reiterated Rodolfo's call for a more comprehensive investigation into the possible existence of a fault.

"Any remote observation has to be verified on the ground," Alcazaren said.

No cause for panic

In a separate interview, Rodolfo explained that it was the Science and Technology Department’s Project Noah (Nationwide Operational Assessment of Hazard) subsidence study that discovered the fault. Rodolfo is as a consultant for Project NOAH.

“The study was conducted mainly because we have lots of evidence on the ground that large areas of Manila are sinking… [My mentioning of the fault was] a side product of our study of areas of subsidence. It gave us the indication that there may be a fault that [was] previously unrecognized,” he told GMA News.

“Ang maganda sa finding namin, kung fault talaga siya, it was manifested because it is moving very slowly,” Rodolfo said.

He noted that his team at Project NOAH is validating their “initial finding.”

“The most important thing is to verify it on the ground. That, I believe, is happening right now. People from Project NOAH are actually going on the ground looking to see whether there is direct evidence on the ground for the existence of the fault,” he added.

Still, the geologist said that the supposed new discovery should not cause panic the public. “It is not the time to make people worried about something as long as we have not really pinned it down scientifically yet.”

Phivolcs assurance

Meanwhile, Phivolcs director Renato Solidum underscored that there is no "new" active fault line in Metro Manila.

Solidum told GMA News that the agency is aware of Rodolfo's findings, but stressed that there is no evidence nor indication of another active fault line in the area. GMANews

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