Phivolcs explains why Pampanga was hit hardest by Luzon quake

Robie de Guzman   •   April 23, 2019   •   18154

MANILA, Philippines – The center of the magnitude 6.1 earthquake that rattled parts of Luzon on Monday was traced in Castillejos, Zambales, but the province of Pampanga recorded the hardest hit.

The Philippine Institute of Volcanology and Seismology (Phivolcs) explained that aside from being a neighbor of Zambales, the province sits on soft sediment and alluvial soil.

Alluvial, in geology, means made up of or found in the materials that are left by the water of rivers, floods among others. An area with softer soil is prone to strong shaking during an earthquake.

Although the temblor was not considered major, Phivolcs said, it was felt by many because it was a bit shallow.

Monday’s earthquake had a depth of 21 kilometers.

“Kaya nagkaroon ng damages sa Pampanga, bukod sa malapit siya sa episentro ng lindol ay malambot yung area na yan. Alluvial area po yung Pampanga kaya malakas yung shaking na mararamdaman,” said Phivolcs Senior Science Research Specialist Melchor Lasala.

(Pampanga recorded heavy damages because aside from being near the quake’s epicenter, the province has soft soil. It is an alluvial area so the shaking was amplified.)

Among the areas that suffered heavy damages were Porac, Angeles and Lubao.

The National Disaster Risk Reduction and Management Council (NDRRMC) on Tuesday reported 16 fatalities in the quake, 15 of which were from Pampanga.

Five people were killed in the collapse of a four-story supermarket in Porac, seven in different barangays in Porac, two in Lubao and one in Angeles.

READ: Luzon quake death toll rises to 16

The earthquake that struck Castillejos, Zambales on Monday was also felt in Metro Manila, parts of Bataan, Tarlac City, Batangas and Cavite.

Phivolcs said it has yet to identify if the recent quake in Luzon originated from an existing active fault in Zambales.

“Yung dalawang fault system na tinitingnan namin yung Iba Fault at East Zambales Fault,” Lasala said.

(We are looking at two fault systems, the Iba and East Zambales fault.)

Lasala added that the movement felt on Monday was called “strike slip”.

“‘Pag strike slip may dalawa tayong slab yung fault—yung left at yung right. Sa behavior, horizontal yung movement niya. ‘Yung isa papunta sa kaliwa yung isa sa papunta sa kanan,” Lasala explained.

Strike-slip faults are vertical (or nearly vertical) fractures where the blocks have mostly moved horizontally, according to the United States Geological Survey (USGS) earthquake glossary.

If the block opposite an observer looking across the fault moves to the right, the slip style is termed right lateral; if the block moves to the left, the motion is termed left lateral. 

Phivols also believes that the magnitude 6.1 quake that jolted Zambales will not trigger a movement of the West Valley Fault as it is 100 kilometers away from the epicenter traced in the Castillejos town.

According to a 2004 study, the West Valley Fault runs through the cities of Marikina, Pasig and Muntinlupa. It is capable of generating a magnitude 7.2 quake that could kill up to 34,000 people and injure 100,000 others. — Robie de Guzman (with details from Rey Pelayo)

Phivolcs sees geohazard, flooding risks in Bulacan Airport

Aileen Cerrudo   •   September 25, 2020

The project site of the proposed New Manila International Airport in Bulacan has geohazard risks, according to the Philippine Institute of Volcanology and Seismology (Phivolcs).

The multi-billion airport is sitting on soft ground and its location is prone to frequent flooding, according to Phivolcs Usec. Renato Solidum.

“Just to be very specific on the facts is that it is far away from the fault. But since it’s underlain by sand with a shallow water table, it’s prone to strong ground shaking and liquefaction,” he said.

Solidum said they conducted an assessment to ensure the safety of the community as well as to protect investments. He recommended making buildings and infrastructure resilient to hazards.

“Dapat iyong building mo ay maayos ang disenyo na maging stable siya habang lumilindol at hindi siya tumagilid. Or pwede mo ring patibayan ang lupa. Bawasan mo iyong tubig, palitan mo iyong lupa, (The building should have a proper design for it to be stable during earthquakes. The ground can also be strengthen by reducing its water content or replacing the soil),” he added.

Meanwhile, San Miguel Holdings Corporation (SMC) said they have been taking into account the risks in designing the P740 billion domestic and international airport in Bulacan. The SMC also assured they have studied the project, including its feasibility, and all possible risks.

“The airport’s design fully takes this into account and we have actually started implementing sustainable measures to address flooding in Bulacan that has existed for several decades and has been made worse by clogged waterways and drainages,” according to SMC.

The corporation also tapped three major global airport construction firms to ensure the airport is resilient, sustainable, and will provide the best benefits for all Filipinos. AAC (with reports from Vincent Arboleda)

Magnitude 6.4 rocks Davao Occidental

Maris Federez   •   September 7, 2020

A magnitude 6.4 earthquake shook Davao Occidental at around 11:23 in the evening of Sunday, Sept. 6.

The Philippine Institute of Volcanology and Seismology (Phivolcs) said the tremor was located east of Don Marcelino in Davao Occidental with a depth of 149 kilometers.

The quake was tectonic in origin.

Phivolcs is yet to report initial damage, although it warned of aftershocks in the affected areas. —/mbmf

PHIVOLCS reminds public to prepare for potential hazards amid COVID-19 pandemic

Marje Pelayo   •   July 29, 2020

MANILA, Philippines — Earthquake drills have been suspended since the outbreak of coronavirus disease (COVID-19) occupied the government in the past months. 

The National Risk Reduction and Management Council (NDRRMC) acknowledges the risk of COVID-19 transmission if people engage in drills.

“Delikado pa kasi iyan ngayong may pandemya pa, (That is risky given that we are in the midst of a pandemic),” explained the agency’s spokesperson Mark Timbal.

Timbal said they can still resume as soon as a vaccine for COVID-19 is discovered.

“I believe that we will resume the drills once both an effective treatment program as well as an immunization/vaccine is already available,” he added.

Despite the suspension of the drills, the agency said the public gets the information it needs through the local government units through constant information campaigns about disasters and diseases, specifically health protocols in evacuation centers, wearing face mask, using personal protective equipment and practicing social distancing.

The NDRRMC also conducts online training for that matter. 

But for the Philippine Institute of Volcanology and Seismology (PHIVOLCS), it is still important to always prepare for potential disasters like earthquakes, typhoons and serious floodings even in the midst of a pandemic.

Science and Technology Undersecretary and PHIVOLCS OIC Renator Solidum assured that the agency is constantly conducting online seminars among LGUs and assessing the possible impact of disasters like earthquakes in their respective areas.

PHIVOLCS encourages every member of the family to discuss preparations amongst themselves as to what they will do in case of a serious earthquake like where they could possibly go to be safe. 

Each family also needs to have an emergency kit in place complete with face masks, alcohol or sanitizer.

In the past many large scale disasters minsan merong mga natataong mga pandemic. Mahirap iyon kung hindi handa sa pareho, [In the past, there were large scale disasters that happened along with a pandemic. It’s difficult to be in both situations unprepared,]” Solidum explained.

“We should prepared for both, not only for COVID-19 but also other possible large-scale hazards,” he added.

PHIVOLCS has created applications which can be checked for potential hazards in a specific area and these applications can be accessed through the Georisk Philippines website. MNP (with reports from Rey Pelayo)

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