QUEZON CITY, March 5 (PIA) -- The Quezon City government and the Philippine Institute of Volcanology and Seismology (Phivolcs) have just completed a trenching activity across the West Valley Fault line at Barangay Bagong Silangan, which is intended to identify ground rupture movements and slip rate estimates across the fault line.
The activity involves excavations of two trenches, about 50 meters apart, within the 50-hectare property owned by Banco Filipino at Barangay Bagong Silangan, which according to a Metro Manila Earthquake Impact Reduction Study (MMEIRS), registers high susceptibility to earthquakes, along with Barangay Payatas, also in QC.
As a result of the trenching activity, geologists from Phivolcs recorded evidence of ground displacement, including abrupt change of sediment layers across the fault. The exposed trench walls are also indicative of at least two to three earthquake events have already taken place in the past.
Phivolcs is now in the process of collecting charcoal pieces for carbon-14 analysis to determine the approximate time of the occurrence of said earthquakes and the estimate of the age of the sediment layers affected by the ground displacement.
According to MMEIRS, a magnitude 7.2 earthquake may originate at the West Valley Fault line.
“The Phivolcs findings just validated the claim that the West Valley Fault Line is indeed active,” said Elmo San Diego, action officer of the QC disaster risk reduction management council and head of the city’s department of public order and safety.
In his remarks, San Diego reiterated QC Mayor Herbert Bautista’s call to declare as danger zone the 7-kilometer stretch of the fault system that runs through QC’s periphery.
“The safety of our residents, particularly those living on top of the faultline, is non-negotiable,” said San Diego. “The faultline is unlivable,” he said.
In an earlier statement, the Mayor urged homeowners and residents of areas transected by the West Valley Fault, particularly those living beside and on top of the fault line, to do their part now in the city’s disaster preparedness efforts. He said it will be for their own safety if they will act now and transfer to areas away from the fault line.
“Our plan is to discourage the construction of structures within the 5 meter-wide borders or buffer zone on both sides of the fault line. We are considering declaring this buffer zone as non-residential to avoid further damage in case of ground rupture,” Bautista said.
QC, in partnership with Phivolcs, started as early as April last year the tagging, marking and installation of physical markers at the actual locations of the West Valley fault system, which runs along the periphery of the city through the eastern boundary from the down slope area east of Violago Parkwoods in the northeast to Bagong Silangan to Ugong Norte in the southeast.
Meanwhile, San Diego advised schools and building administrators whose properties transect the West Valley fault line to undertake retrofitting procedures to ensure the stability of their structures.
To heighten the level of preparedness of QC communities in times of calamities, especially earthquakes, continuous orientation programs were also being conducted for QC schoolchildren and barangays. (RJB/AKG-PIA-NCR/QC-PIO)