Phivolcs explains why Pampanga was hit hardest by Luzon quake
Robie de Guzman • April 23, 2019 • 17056
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.
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)
The National Bureau of Investigation (NBI) Central Luzon Regional Office has arrested two Chinese nationals for operating an underground clinic and pharmacy in Angeles, Pampanga.
Authorities raided an underground medical clinic and pharmacy on Volga Street in Barangay Anunas on Thursday (May 28).
The arrested Chinese nationals were identified as 66-year-old Chen Zheng Zhong and 33-year-old son Chen Hai Fang. Chen Zheng Zhong is the doctor treating Chinese patients while his son sells illegal Chinese medicines.
According to the NBI, the suspects used a two-storey apartment as their underground clinic and pharmacy.
“Hindi mo talaga iisipin na mayroong clinic doon sa loob kasi isang apartment lang, (You wouldn’t think that there is a clinic inside because it’s only an apartment),” according to NBI Regional Office 3 Operations Officer Atty. Marvin de Jemil.
“Wala silang permit from the FDA [Food and Drug Administration], and then naghahanap din kami ng business permit, wala din silang permit. Wala rin silang license to operate (They don’ have a permit from the FDA, nor a business permit. They also don’t have a license to operate),” Jemil added.
Upon inspection of the NBI and the FDA, they found six hospital-like beds, two beds on the first floor and four more beds on the second floor of the building.
The two suspects are now detained at the NBI regional Office at City of San Fernando, Pampanga and are facing several charges including the violation of the Medical Act of 1959.AAC (with reports from Leslie Huidem)
MANILA, Philippines – The Philippine Institute of Volcanology and Seismology (Phivolcs) on Thursday said it has downgraded the alert on Taal Volcano to level 1 following the decrease in volcanic quakes and surface activity at the main crater.
In its bulletin, Phivolcs said the Taal Volcano’s condition in the succeeding four weeks after its alert was lowered to level 2, has been characterized by low-level volcanic earthquake activity, stabilizing ground deformation of the Taal Caldera and the Taal Volcano Island edifices, and weak surface activity at the Main Crater and the Daang Kastila fissure.
“DOST-PHIVOLCS is lowering the alert status of Taal Volcano from Alert Level 2 to Alert Level 1 to reflect the overall decreasing trend in the level of monitoring parameters,” its bulletin reads.
State volcanologists said that alert level 1 means that the volcano is still in “abnormal condition,” and that this “should not be interpreted that unrest has ceased or that the threat of an eruption has disappeared.”
Under alert level 1, sudden steam-driven or phreatic explosions, volcanic earthquakes, minor ashfall and lethal accumulations or expulsions of volcanic gas can occur and threaten areas within the Taal Volcano Island.
The alert level may be raised back to alert level 2 “should pronounced change in monitored parameters forewarn of renewed unrest,” Phivolcs said.
The agency reminded residents that entry to Taal’s permanent danger zone, especially the vicinities of the Main Crater and the Daang Kastila fissure, remains strictly prohibited.
The Taal Volcano was placed under alert level 4 when it spewed ash on January 12 which sent thousands of residents to temporary shelters and disrupted businesses in surrounding areas.
It was later lowered to alert level 2 several weeks later due to decreased unrest. — ROBIE DE GUZMAN
MANILA, Philippines – The Philippine Institute of Volcanology and Seismology (PHIVOLCS) reported only about 29 volcanic earthquakes around Taal Volcano in the past 24 hours, an indication that rocks underground are breaking.
A column of white steam also continues to form but only up to 50 meters in height.
It has been a week since PHIVOLCS downgraded alert level over the Taal volcano to level 2 from the previous level 3.
According to PHIVOLCS OIC Usec. Renato Solidum, they need to observe Taal volcano’s activities for one more week before they can decide whether to further downgrade the alert status based on the agency’s standard operating procedure.
“Basta tuloy-tuloy ang kanyang mga parametro na bumababa ang bilang pwede natin masabi na pwede nating ibaba ito sa alert level number one (If the parameters continue to reduce in number, we might lower the alert level to number one),” Solidum said.
Entry restrictions remain within the permanent danger zone in Taal Volcano Island.
Solidum said the local government unit needs to assess first if the former residential areas would be conducive for living.
PHIVOLCS does not recommended constructing houses on the volcano island due to the risk of having the ground break apart should the volcano proceed to erupt. MNP (with details from Rey Pelayo)
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