Location:

Period:

14 Jun 2009 05:58:43 - 14 Jun 2009 21:22:36 (15 hours 23 minutes)

Volcanoes in 100km radius:

None

Earthquakes:

M 7.0+:

M 7.0; 96 km ESE of Pondaguitan, Philippines; (29 Dec 2018) (64km from the swarm center)

11 swarms found nearby.

2001

PS20010101.1(146.0km)

1 Jan

1 day 0 hours

9 earthquakes

2006

PS20061023.1(141.9km)

23 Oct

1 day 4 hours

11 earthquakes

2009

PS20090211.1(162.0km)

11 Feb

2 days 11 hours

67 earthquakes

PS20090316.1(198.9km)

16 Mar

3 hours

5 earthquakes

2017

PS20170410.1(87.2km)

10 Apr

1 day 7 hours

14 earthquakes

2019

PS20191215.1(195.1km)

15 Dec

6 hours

8 earthquakes

2021

PS20210812.1(93.7km)

11 Aug

1 day 3 hours

8 earthquakes

2022

PS20220505.1(131.9km)

4 May

1 day 3 hours

7 earthquakes

PS20220508.1(199.3km)

8 May

14 hours

5 earthquakes

2026

PS20260608.1(135.3km)

7 Jun

3 days 12 hours

38 earthquakes

PS20260613.1(121.1km)

12 Jun

1 day 2 hours

6 earthquakes

AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Seismic Swarm PS20090614.1 in Mindanao, Philippines

Mindanao lies within the tectonically active Philippine Mobile Belt, where the Philippine Sea Plate converges with the Sunda Plate. This interaction produces multiple subduction zones, including the Philippine Trench to the east and the Cotabato Trench to the southwest, along with strike-slip faults such as the Philippine Fault. The island experiences frequent seismicity due to these plate-boundary processes, with earthquakes occurring at varying depths from shallow crustal events to deeper subduction-related activity.

On 14 June 2009, a seismic swarm designated PS20090614.1 was recorded in Mindanao. The sequence began at 05:58 and concluded at 21:22 local time, spanning 15 hours and 23 minutes. Five earthquakes were registered during this period. The events occurred at depths between 25 km and 61 km, with magnitudes ranging from 4.7 to 6.1.

The first and largest event measured magnitude 6.1 at a depth of 35 km. Subsequent shocks included a magnitude 5.4 event at 35 km depth, followed by a magnitude 5.1 at 25 km. Later in the sequence, a magnitude 5.3 occurred at 61 km depth, and the final event registered magnitude 4.7 at 47 km. Such swarms typically reflect fluid migration or stress adjustments along fault systems rather than a single mainshock-aftershock pattern.

Historical records indicate four seismic swarms in the region since 1 January 2000. These occurred in 2001 (one swarm), 2006 (one swarm), and 2009 (two swarms). The 2009 activity, including PS20090614.1, aligns with the island’s recurrent swarm patterns linked to its complex fault network.

A notable strong earthquake took place on 29 December 2018, with magnitude 7.0 located 96 km east-southeast of Pondaguitan, approximately 64 km from the 2009 swarm center. This event underscores the ongoing seismic hazard in the area, where deeper subduction earthquakes can influence regional stress fields.

Seismic monitoring in Mindanao benefits from regional networks that track both swarm activity and larger events. Continued observation helps refine understanding of fault interactions and improves hazard assessment for this densely populated island.

References

Philippine Institute of Volcanology and Seismology (PHIVOLCS) seismic bulletins
United States Geological Survey (USGS) earthquake catalog
SeismoSight internal swarm classification records