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Location:
34 km E of Hinatuan, Philippines
Period:
2 Dec 2023 14:58:41 - 7 Dec 2023 04:06:55 (4 days 13 hours 8 minutes)
Volcanoes in 100km radius:
None
Earthquakes:
158
10 swarms found nearby.
2009
PS20090521.1(56.4km)
21 May
8 hours
5 earthquakes
2014
PS20140530.1(114.9km)
30 May
5 hours
6 earthquakes
PS20140531.1(114.4km)
31 May
1 hours
9 earthquakes
2018
PS20181029.1(40.9km)
29 Oct
7 hours
5 earthquakes
2023
PS20231202.1(56.4km)
2 Dec
5 days 19 hours
107 earthquakes
2 Dec
3 days 8 hours
49 earthquakes
S20231203.2(20.6km)
2 Dec
5 days 21 hours
67 earthquakes
PS20231212.1(23.0km)
11 Dec
14 hours
5 earthquakes
PS20231224.1(20.8km)
23 Dec
15 hours
5 earthquakes
2024
PS20240803.1(27.2km)
2 Aug
5 hours
7 earthquakes
AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Seismic Swarm East of Hinatuan, Philippines: December 2023 Analysis

A seismic swarm designated S20231202.2 occurred east of Hinatuan in Surigao del Sur province, Philippines. The sequence began at 14:58 on 2 December 2023 and concluded at 04:06 on 7 December 2023, spanning 109 hours and 8 minutes. During this period, 158 earthquakes were recorded at a location 34 km east of Hinatuan.

The swarm reflects the tectonic setting of eastern Mindanao, situated within the Philippine Mobile Belt. This region experiences active deformation due to oblique convergence between the Philippine Sea Plate and the Eurasian Plate. The Philippine Trench lies offshore to the east, while the Philippine Fault system traverses the island, accommodating lateral shear. Seismicity at intermediate depths commonly arises from slab-related processes within the subducting Philippine Sea Plate.

Analysis of the first 100 events reveals magnitudes predominantly between 4.0 and 4.9, with occasional events reaching 3.0–3.4. Depths cluster mainly between 40 km and 80 km, consistent with intermediate-depth activity along the subducting slab. Shallower events below 30 km appear less frequently and may relate to crustal adjustments. The temporal distribution shows a rapid onset with multiple events within the first hours, followed by sustained activity over subsequent days before gradual decline.

Historical records indicate five prior swarms in the same area since 2000. These occurred in 2009 (one swarm), 2014 (two swarms), 2018 (one swarm), and earlier in 2023 (one swarm). Such episodic clustering underscores the recurrent nature of swarm-type seismicity in this segment of the subduction zone, distinct from typical mainshock-aftershock sequences.

The December 2023 swarm did not produce reported damage or significant ground deformation at the surface, consistent with the moderate magnitudes and depths involved. Continued monitoring remains essential given the region's position along major tectonic boundaries.

References

Philippine Institute of Volcanology and Seismology (PHIVOLCS) earthquake bulletins and regional tectonic summaries.
US Geological Survey Earthquake Hazards Program data on Philippine seismicity.
Peer-reviewed literature on Philippine Mobile Belt tectonics and subduction processes.