5.0-magnitude quake jolts Davao de Oro — Phivolcs

by Ellalyn De Vera-Ruiz, Manila Bulletin

A moderately strong earthquake measuring 5.0-magnitude on the Richter scale shook Davao de Oro and nearby provinces on Friday evening, March 11, said the Philippine Institute of Volcanology and Seismology (Phivolcs).

In its initial bulletin, Phivolcs said the epicenter of the earthquake was traced 9 kilometers (km) northwest of Monkayo, Davao de Oro, and occurred at a shallow depth of 18 km. It was detected at around 10:14 p.m.

It was felt as a “moderately strong” tremor at Intensity IV in Rosario, Agusan del Sur and Maco, Davao de Oro, while it was “slightly weak” at Intensity II in Bayugan City, Agusan del Sur.

Phivolcs’ instruments also recorded the quake at Intensity II in Bislig City, Surigao del Sur and Intensity I in Davao City.

It said the earthquake may have caused damage to the affected areas.

Phivolcs said the earthquake was tectonic in origin, which means it was caused by the movement of an active fault near the area.

It advised the public to stay vigilant as aftershocks may occur due to this earthquake.

Phivolcs: 'Very weak' phreatomagmatic bursts recorded in Taal Volcano

(MANILA BULLETIN / FILE PHOTO)

by Ellalyn De Vera-Ruiz, Manila Bulletin

Eight “very weak” phreatomagmatic bursts have been recorded in Taal Volcano on Saturday, Jan. 29, said the Philippine Institute of Volcanology and Seismology (Phivolcs).

In its advisory late Saturday night, Phivolcs said short phreatomagmatic bursts, which lasted only 10 seconds to two minutes, occurred between 3:50 p.m. and 9:57 p.m.

 

Phreatomagmatic burst occurs when hot magma comes into contact with groundwater.

Phivolcs said the “very short-lived” bursts “produced only traces in the seismic record but were accompanied by distinct infrasound signals.”

However, the events generated steam-rich plumes between 400 meters and 900 meters high as detected by visual and thermal cameras around Taal Lake.

“Sulfur dioxide flux since the beginning of 2022 has averaged 10,668 tons per day, with the highest average emission at 18,705 tons per day on January 27, 2022,” Phivolcs said.

Meanwhile, “almost no volcanic earthquake activity has been recorded since Dec. 19,” it pointed out, adding that the volcano island has been deflating since October 2021.

Phivolcs said that Taal Volcano remains under alert level 2, which means that the volcano continues to manifest “increased unrest.” The volcano has been under alert level 2 since July 23, 2021.

It warned that gas-driven explosions and lethal accumulations or expulsions of volcanic gas can occur and affect areas within and around the Taal Volcano Island.

Phivolcs reiterated that entry into the Taal Volcano Island, which is a permanent danger zone, especially the vicinities of the main crater and the Daang Kastila fissure, is strictly prohibited.

Boating and other activities on Taal Lake are also prohibited, Phivolcs said.

“Local government officials are advised to continuously assess and strengthen the preparedness of previously evacuated barangays around Taal Lake in case of renewed unrest,” it added.

Earthquakes Occuring Everyday in The Philippines

 

While writing this piece I received some messages from good friends in Cebu City telling me, that this area has been hit by another strong earthquake just an hour ago. Tsunami warning has been given out.

Saturday, another quake initially measuring 6.0 in magnitude struck Samar Island. The quake hit at 9 p.m. at a depth of 60 kilometres north of the city of Guiuan. The epicenter was around 600 km away east of Manila. 

The Philippine Institute of Volcanology and Seismology said that low-magnitude earthquakes occur daily based on its intensity Scale. Honestly, I experienced this since living in the Philippines for good.

Looking back, last Wednesday two minor earthquakes have occurred. The latest was a magnitude 3.5 of tectonic origin hitting 25 kilometres north of San Julian, Eastern Samar with a 16 km depth of focus. The other hit 30 km south-east of Sta. Ana, Cagayan also of tectonic origin with a magnitude 3.2 having a 12 km depth of focus. 

Imagine, last Tuesday six minor tremors occurred in Bolinao, Pangasinan; Borongan, Samar; Infanta; Pangasinan; Vigan, Ilocos Sur and Burgos, Surigao del Norte.