Location:

Period:

11 Nov 2014 05:04:42 - 11 Nov 2014 08:40:18 (3 hours 35 minutes)

Volcanoes in 100km radius:

None

Earthquakes:

15 swarms found nearby.

2004

PS20041226.3(192.5km)

26 Dec

2 days 1 hours

25 earthquakes

PS20041226.5(171.1km)

26 Dec

1 day 11 hours

20 earthquakes

2005

PS20050101.3(178.6km)

1 Jan

1 day 1 hours

6 earthquakes

S20050127.1(65.5km)

26 Jan

4 days 22 hours

168 earthquakes

S20050127.2(32.2km)

26 Jan

3 days 18 hours

105 earthquakes

PS20050126.1(60.0km)

26 Jan

5 days 20 hours

98 earthquakes

S20050128.1(32.6km)

27 Jan

2 days 5 hours

44 earthquakes

S20050129.1(58.9km)

28 Jan

1 day 12 hours

33 earthquakes

PS20050205.1(78.3km)

4 Feb

2 days 6 hours

10 earthquakes

PS20050216.1(111.3km)

15 Feb

16 hours

5 earthquakes

2014

PS20140321.1(24.0km)

21 Mar

7 hours

7 earthquakes

2015

PS20151108.1(131.1km)

8 Nov

21 hours

11 earthquakes

2019

PS20190401.1(16.7km)

31 Mar

8 hours

12 earthquakes

2021

PS20210803.1(151.8km)

3 Aug

2 hours

5 earthquakes

2023

PS20230409.1(184.7km)

9 Apr

13 hours

5 earthquakes

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Seismic Swarm Activity Northwest of Sabang, Indonesia: The November 2014 Event

On 11 November 2014, a seismic swarm designated PS20141111.1 was recorded 219 km NNW of Sabang, Indonesia. The sequence began at 05:04 and concluded at 08:40 local time, encompassing five earthquakes over 3 hours and 35 minutes. This cluster occurred within a tectonically active offshore region influenced by the Sunda subduction zone.

The broader geological setting northwest of Sumatra lies along the convergent boundary where the Indo-Australian plate subducts beneath the Eurasian plate. This process has shaped the Sunda Trench and generates frequent seismicity across the Andaman Sea and adjacent waters. Historical records indicate that the area experiences both isolated large-magnitude events and episodic swarm activity driven by stress transfer along the subduction interface and associated crustal faults.

Swarm sequences in this region are characterized by closely spaced events without a dominant mainshock. The 2014 swarm followed this pattern, with the following progression: an initial magnitude 5.1 event at 05:04:42 at 10 km depth; a magnitude 5.3 event at 07:50:07 at 8 km depth; a second magnitude 5.3 event at 07:50:13 at 40 km depth; a magnitude 5.1 event at 08:04:35 at 10 km depth; and a final magnitude 4.4 event at 08:40:18 at 10 km depth. Depths remained predominantly shallow, consistent with activity near the plate interface.

Regional statistics since 2000 show eleven documented swarms. Earlier episodes occurred in 2004 (two swarms) and 2005 (eight swarms), with the 2014 sequence representing the sole event recorded that year. These clusters reflect episodic strain release within the subduction system.

Such swarms contribute to ongoing monitoring of seismic hazards in northern Sumatra and the Andaman region. Continued observation aids in refining models of plate coupling and stress accumulation along the trench.

References

USGS Earthquake Catalog
Global CMT Project
Indonesian Meteorological, Climatological, and Geophysical Agency (BMKG) reports