Location:

Period:

7 Jun 2026 23:37:41 - 11 Jun 2026 11:46:58 (3 days 12 hours 9 minutes)

Volcanoes in 100km radius:

Balut(60km)

Earthquakes:

M 7.0+:

M 7.8; 26 km SW of Kablalan, Philippines; (7 Jun 2026) (94km from the swarm center)

7 swarms found nearby.

2002

PS20020306.1(144.4km)

5 Mar

22 hours

6 earthquakes

2006

PS20061023.1(20.6km)

23 Oct

1 day 4 hours

11 earthquakes

2009

PS20090211.1(164.8km)

11 Feb

2 days 11 hours

67 earthquakes

PS20090316.1(190.0km)

16 Mar

3 hours

5 earthquakes

PS20090614.1(135.3km)

14 Jun

15 hours

5 earthquakes

2019

PS20191215.1(194.6km)

15 Dec

6 hours

8 earthquakes

2026

PS20260613.1(47.5km)

12 Jun

1 day 2 hours

6 earthquakes

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Seismic Swarm PS20260608.1: Analysis of Activity in Mindanao, Philippines

A seismic swarm designated PS20260608.1 occurred in Mindanao, Philippines, beginning at 23:37 on 7 June 2026 and concluding at 11:46 on 11 June 2026. Over 84 hours and 9 minutes, 38 earthquakes were recorded. The sequence featured a prominent initial event of magnitude 7.8 at 55 km depth, followed by multiple aftershocks ranging from magnitude 4.8 to 6.5, with focal depths between 10 km and 89 km. This activity aligns with Mindanao's position in a tectonically complex zone.

Mindanao lies within the Pacific Ring of Fire, where the Philippine Sea Plate subducts beneath the Sunda Plate along the Philippine Trench to the east and the Cotabato Trench to the west. The region is further influenced by the Philippine Fault, a major left-lateral strike-slip system traversing the archipelago. These interactions generate frequent seismicity, with crustal deformation accommodated through both shallow crustal faults and deeper subduction-related events. Depths recorded in the swarm, predominantly 35–70 km, suggest involvement of the subducting slab interface and overlying crust.

Historical seismic patterns in Mindanao since 2000 include six prior swarms: one in 2002, one in 2006, three in 2009, and one in 2019. These episodes typically involve clustered moderate-magnitude events without a single dominant mainshock. The 2026 swarm deviates by including a magnitude 7.8 shock located 26 km southwest of Kablalan, approximately 94 km from the swarm centroid. Such events underscore the potential for larger ruptures along subduction segments.

The temporal distribution shows intense early activity on 7–8 June, with magnitudes exceeding 6.0 clustered in the first hours, transitioning to more moderate events through 11 June. Depths varied, indicating possible migration along fault planes or within the Wadati-Benioff zone. This pattern reflects stress release across multiple segments of the regional fault network.

Geological records confirm Mindanao's high seismicity, driven by oblique convergence rates of 6–8 cm per year. Past large events have demonstrated the capacity for tsunamigenic quakes and surface rupture along the Philippine Fault. The 2026 swarm contributes to ongoing monitoring of strain accumulation in the southern Philippines.

References
Philippine Institute of Volcanology and Seismology (PHIVOLCS) tectonic summaries.
USGS Earthquake Catalog regional data for Mindanao.
Global CMT Project focal mechanism database.