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Movement along hidden fault caused April 22 Luzon quake — PHIVOLCS
The magnitude-6.1 earthquake that shook parts of Luzon last week occurred along a hidden fault that had not been previously plotted, PHIVOLCS said.
According to a report by Lei Alviz on 24 Oras on Monday, the earthquake-monitoring agency said that hidden faults are those that have not been detected because the movement along them have not manifested as marks on the surface of the earth.
"Pag meron siyang surface manifestation, nalalaman namin kung gaano kahaba 'yung fault, at nae-estimate namin 'yung gaano kalakas 'yung pwede niyang i-generate," said geologist and supervising science research specialist Jeffrey Perez.
In the case of a hidden fault, he added, "Alam namin kung nasaan siya sa ilalim, siguro, pero to project it sa ground, 'yun 'yung medyo mahirap. Kailangan ng detalyadong pag-aaral."
The 7.2-magnitude quake that rattled Bohol in 2013 also occurred along a hidden fault, whose surface manifestation only appeared during the quake.
"Ke hidden man 'yan o nakikita sa ground, pareho pa rin 'yung preparedness na dapat nating igawa," he said.
20 quakes a day
The country is part of the Ring of Fire, a 40,000-kilometer zone on the edges of the Pacific Ocean along which are arrayed hundreds of active underwater volcanoes. Most of the world's earthquakes occur on the Ring of Fire.
The Philippines is crossed by several known faultlines, the longest of which is the 1,200 kilometer-long Philippine Fault Zone, which runs from northern Luzon to eastern Mindanao.
In the report, Perez pointed to a seismicity map of the Philippines that showed the epicenters of hundreds of earthquakes that occurred in 2016.
"'Yung bawat isang bilog, isang epicenter ng earthquake, so in terms of numbers ang nare-record natin sa PHIVOLCS on average at least 20 earthquakes every day," he said.
Of these, he added, "Four hanggang limang lindol yung nararamdaman ng tao every week." — BM, GMA News
