Monday evening brought renewed trembling to parts of Mindanao when a magnitude 4.6 aftershock rolled through multiple provinces at 7:22 PM on June 8, 2026 — a continuation of the seismic unrest triggered by the much stronger Mw7.8 earthquake that had struck offshore Sarangani earlier that day. The Philippine Institute of Volcanology and Seismology (PHIVOLCS-DOST) released Earthquake Information No. 1 at 7:34 PM Philippine Standard Time, confirming the event and assuring the public that no damage is expected.
Origin and Technical Details of the Aftershock
According to PHIVOLCS-DOST, the aftershock originated approximately 22 kilometers south-southwest of Balut Island, which falls within the Municipality of Sarangani in Davao Occidental. The recorded coordinates were 5.31°N, 125.25°E, placing the epicenter in an offshore location southwest of the island.
PHIVOLCS classified the earthquake as tectonic in origin. The focal depth was measured at 55 kilometers beneath the surface, and the surface-wave magnitude was recorded at Ms 4.6. The agency formally identified this event as an aftershock of the Mw7.8 Offshore Sarangani earthquake, which also struck on June 8, 2026.
Shaking Felt Across Multiple Provinces
PHIVOLCS-DOST reported that the tremor was felt instrumentally across several areas in Mindanao, with varying intensity levels measured according to the PHIVOLCS Earthquake Intensity Scale (PEIS). The areas and their corresponding intensities are as follows:
Intensity IV
The strongest shaking from this aftershock was recorded in T'Boli, South Cotabato, reaching Intensity IV on the PEIS. At this level, the shaking is typically felt by many people who are indoors, and hanging objects are observed to swing noticeably.
Intensity III
Intensity III was recorded in several communities, including Tupi in South Cotabato, Bagumbayan in Sultan Kudarat, Maitum in Sarangani, and Sta. Maria in Davao Occidental. An Intensity III event is generally felt by several people inside buildings, producing a slight vibration often compared to the sensation of a vehicle passing nearby.
Intensity II
A weaker but still perceptible shaking at Intensity II was reported in Kalamansig in Sultan Kudarat; Banga, Santo Niño, Surallah, and Tampakan in South Cotabato; and Digos City, Matanao, and Magsaysay in Davao del Sur. Intensity II is typically felt only by a few individuals, particularly those at rest or on upper floors of buildings.
Intensity I
The lowest recorded shaking, Intensity I, was noted in Columbio and President Quirino in Sultan Kudarat. This level is described by PHIVOLCS as scarcely perceptible, noticeable only under particularly favorable conditions.
No Damage Expected, No Further Bulletins Anticipated
PHIVOLCS-DOST stated in its official bulletin that the magnitude 4.6 aftershock is not expected to cause any damage to structures or communities in the affected areas. The agency also noted that no further aftershocks are anticipated specifically from this event.
In line with standard operating procedure, PHIVOLCS-DOST stated that this earthquake information bulletin will be the only one issued for this particular aftershock, unless new or additional data warrants a follow-up report.
Broader Seismic Context: The Mw7.8 Sarangani Earthquake
This magnitude 4.6 tremor is part of the wider aftershock sequence that followed the Mw7.8 Offshore Sarangani earthquake, which struck on the same date — June 8, 2026 — according to PHIVOLCS-DOST. Major earthquakes of this magnitude routinely produce a series of aftershocks of varying sizes in the hours, days, and even weeks that follow the main event.
The epicenter of this aftershock was situated offshore, in waters to the southwest of Balut Island in Davao Occidental. PHIVOLCS-DOST has published an epicentral map alongside the official bulletin to assist the public and local government units in understanding the geographic scope of the seismic activity.
Residents in the affected areas are advised to stay alert and to monitor official updates from PHIVOLCS-DOST, which remain the authoritative source for seismic information in the Philippines. The agency's official website, phivolcs.dost.gov.ph, carries the latest bulletins and earthquake data for public access.
Authorities have not reported casualties or structural damage connected to this specific aftershock as of the time of the PHIVOLCS-DOST bulletin issuance at 7:34 PM on June 8, 2026.
Originally reported by: breakingnewsnegor.com