Location:

Period:

2 Apr 2026 03:07:35 - 10 Apr 2026 16:29:33 (8 days 13 hours 21 minutes)

Volcanoes in 100km radius:

Hiri(97km)

Earthquakes:

107

13 swarms found nearby.

2001

PS20010225.1(28.2km)

24 Feb

16 hours

5 earthquakes

PS20010226.1(42.3km)

26 Feb

12 hours

5 earthquakes

PS20010827.1(10.5km)

26 Aug

1 day 19 hours

9 earthquakes

2007

PS20070121.1(33.3km)

21 Jan

3 days 13 hours

42 earthquakes

PS20070127.1(18.7km)

26 Jan

1 day 17 hours

7 earthquakes

2014

PS20141115.1(78.6km)

15 Nov

8 hours

8 earthquakes

PS20141126.1(83.6km)

25 Nov

1 day 0 hours

8 earthquakes

PS20141221.1(111.8km)

21 Dec

2 hours

5 earthquakes

2019

PS20190708.1(47.0km)

8 Jul

21 hours

5 earthquakes

PS20191114.1(47.7km)

14 Nov

1 day 7 hours

29 earthquakes

2026

PS20260402.1(38.9km)

1 Apr

2 days 2 hours

23 earthquakes

S20260402.1(20.0km)

1 Apr

12 days 18 hours

397 earthquakes

S20260402.4(26.2km)

1 Apr

11 days 20 hours

228 earthquakes

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Seismic Swarm S20260402.5 in the Molucca Sea: Analysis of April 2026 Activity

The Molucca Sea, situated in eastern Indonesia between the islands of Sulawesi and Halmahera, forms a critical segment of the Pacific Ring of Fire. This region experiences intense seismic activity driven by the complex convergence of the Philippine Sea Plate, the Sunda Plate, and smaller microplates. Subduction along the Molucca Sea Collision Zone and associated thrust faults generates frequent earthquakes, with depths often ranging from shallow crustal levels to intermediate depths exceeding 100 km. Historical records indicate that the area has hosted numerous seismic swarms, reflecting episodic stress release along these tectonically active boundaries.

Seismic swarm S20260402.5 began at 03:07 on 2 April 2026 and concluded at 16:29 on 10 April 2026, spanning 205 hours and 21 minutes. During this period, 107 earthquakes were recorded. Analysis of the first 100 events reveals a predominance of shallow-focus tremors, with depths mostly between 4 km and 50 km. Magnitudes clustered between 2.5 and 5.0, including several events above 4.0. Notable occurrences include a 4.7 magnitude quake at 3 km depth on 2 April, a 4.8 magnitude event at 47 km on 3 April, and the swarm's peak of 5.0 magnitude at 17 km depth on 6 April. Activity showed temporal clustering, with higher rates on 2–4 April and 6–8 April, followed by a gradual decline. Depths remained predominantly crustal, consistent with thrust faulting in the collision zone.

This swarm aligns with the Molucca Sea's established pattern of seismic clustering. Since 1 January 2000, 13 swarms have occurred in the region, distributed across 2001 (3 swarms), 2007 (2), 2014 (3), 2019 (2), and 2026 (3). These episodes typically involve low-to-moderate magnitude events without a single dominant mainshock, distinguishing them from typical aftershock sequences. The 2026 activity reinforces the area's ongoing tectonic strain accumulation, where plate convergence rates exceed 5 cm per year.

Geologically, the Molucca Sea Collision Zone represents an active arc-arc collision, producing both volcanic arcs and frequent seismicity. Updated monitoring confirms persistent microseismicity alongside larger events, underscoring the need for continued surveillance in this densely populated maritime region.

References

United States Geological Survey (USGS) Earthquake Catalog
SeismoSight Internal Swarm Classification Database