Location:

Period:

2 Apr 2026 00:20:43 - 7 Apr 2026 01:55:58 (5 days 1 hour 35 minutes)

Volcanoes in 100km radius:

None

Earthquakes:

114

16 swarms found nearby.

2001

PS20010225.1(9.4km)

24 Feb

16 hours

5 earthquakes

PS20010226.1(7.8km)

26 Feb

12 hours

5 earthquakes

PS20010827.1(35.2km)

26 Aug

1 day 19 hours

9 earthquakes

2007

PS20070121.1(38.6km)

21 Jan

3 days 13 hours

42 earthquakes

PS20070127.1(19.0km)

26 Jan

1 day 17 hours

7 earthquakes

2014

PS20141115.1(49.7km)

15 Nov

8 hours

8 earthquakes

PS20141126.1(53.0km)

25 Nov

1 day 0 hours

8 earthquakes

PS20141221.1(82.8km)

21 Dec

2 hours

5 earthquakes

2019

PS20190708.1(76.9km)

8 Jul

21 hours

5 earthquakes

PS20191114.1(18.3km)

14 Nov

1 day 7 hours

29 earthquakes

2026

PS20260402.1(23.2km)

1 Apr

2 days 2 hours

23 earthquakes

S20260402.1(16.4km)

1 Apr

12 days 18 hours

397 earthquakes

S20260402.4(24.8km)

1 Apr

11 days 20 hours

228 earthquakes

S20260402.2(10.4km)

2 Apr

5 days 5 hours

150 earthquakes

S20260403.1(26.8km)

2 Apr

2 days 8 hours

57 earthquakes

S20260404.1(21.7km)

3 Apr

1 day 10 hours

43 earthquakes

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Seismic Swarm S20260402.3 in the Molucca Sea: Geological Context and Event Analysis

The Molucca Sea, situated in eastern Indonesia between the islands of Sulawesi and Halmahera, represents one of the world's most tectonically complex regions. This area lies at the convergence of the Philippine Sea Plate, the Molucca Sea microplate, and the Sunda Plate, resulting in a collision zone characterized by opposing subduction systems and intense seismic activity. The double subduction geometry produces frequent earthquakes, with hypocenters commonly occurring at shallow to intermediate depths.

Seismic swarms have occurred periodically in this setting. Historical records since 2000 indicate 13 documented swarms, occurring in 2001 (3 events), 2007 (2), 2014 (3), 2019 (2), and 2026 (3). These episodes reflect episodic stress release along the intricate fault networks of the collision zone rather than typical mainshock-aftershock sequences.

Swarm S20260402.3 initiated at 00:20 on 2 April 2026 and concluded at 01:55 on 7 April 2026, spanning 121 hours and 35 minutes. During this period, 114 earthquakes were recorded. Analysis of the first 100 events reveals predominantly shallow focal depths between 4 km and 57 km, with the majority clustered between 6 km and 20 km. Magnitudes ranged from 2.5 to 4.8, featuring multiple events of magnitude 4.0–4.7 and isolated peaks reaching 4.8. Activity showed temporal clustering, with elevated rates during the initial 48 hours followed by a gradual decline, consistent with swarm behavior driven by fluid migration or aseismic slip.

The Molucca Sea Collision Zone remains highly active due to ongoing plate convergence at rates exceeding 10 cm per year in places. This tectonic framework explains the recurrence of seismic swarms and underscores the need for continued monitoring in this densely populated region of Indonesia.

References

Hall, R. (2012). Late Jurassic–Cenozoic reconstructions of the Indonesian region and the Indian Ocean. Tectonophysics, 570–571, 1–41.
USGS Earthquake Hazards Program. (n.d.). Earthquake catalog for the Molucca Sea region.