Manila Trench segment could trigger magnitude 8.4 quake -PHIVOLCS

A recent sequence of offshore earthquakes off Ilocos Sur has been traced to the Manila  Trench, prompting concerns over the potential for a high-magnitude earthquake, according to the Philippine Institute of  Volcanology and Seismology (PHIVOLCS).

The quakes, which occurred near Santa Catalina town, have raised the possibility of a worst-case scenario: a magnitude 8.4 earthquake originating from the movement of this segment of the Manila Trench.

In a tsunami simulation, PHIVOLCS divided the Manila Trench into four segments to better assess the risks. According to the simulation, such an earthquake could generate a tsunami with waves ranging from three to 15 meters in height.

“Kapag nakalikha ito ng tsunami, ang unang alon ay  makakarating sa baybayin ng mga probinsya ng Zambales, Pangasinan, La  Union, Ilocos Sur, Ilocos Norte, at Cagayan sa loob ng dalawa (2)  hanggang 15 minuto. Samantala, ang taas ng alon ay maaaring umabot ng  tatlo hanggang 15 metro,” PHIVOLCS stated.

(Once it produces a tsunami, the first wave could reach the shores of  Zambales, Pangasinan, La Union, Ilocos Sur, Ilocos Norte, and Cagayan within two to 15 minutes. Meanwhile, the wave height could reach up to 3 to 15 meters.)

According to PHIVOLCS’ calculations, the tsunami could arrive in as little as two minutes in Palauig, Zambales.  The highest waves, reaching up to 14.7 meters, could hit Vigan, Ilocos  Sur.

Since 4:02 a.m. on December 17, PHIVOLCS has recorded 49  offshore earthquakes west-northwest of Santa Catalina. The magnitudes of these earthquakes ranged from 1.8 to 5.0.

The earthquakes have been attributed to movements along the Manila Trench, an ocean trench located west of the Philippines that reaches depths of up to  5,400 meters.

Despite these findings, PHIVOLCS emphasized that earthquakes and tsunamis cannot be precisely predicted. The agency  urged the public to remain vigilant and watch for signs of a potential  tsunami, such as:

• strong earthquake,
• sudden changes in sea level,
• unusual sounds coming from the sea.

—  DVM, GMA Integrated News