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Note:This page contains AI-generated content for informational and entertainment purposes only. It may contain inaccuracies. Raw event data is from USGS and EMSC. All statistics, lists, and derived information are generated by this site. Full disclaimerFound an error?
Location:
STRAIT OF GIBRALTAR
Period:
7 Apr 2022 03:56:28 - 5 May 2022 20:29:53 (28 days 16 hours 33 minutes)
Volcanoes in 100km radius:
None
Earthquakes:
392
16 swarms found nearby.
2016
PS20160125.1(16.7km)
25 Jan
1 hours
6 earthquakes
2021
15 May
3 days 23 hours
51 earthquakes
6 Jun
11 days 1 hours
144 earthquakes
S20210730.3(22.1km)
29 Jul
57 days 9 hours
1361 earthquakes
S20211114.1(12.2km)
13 Nov
5 days 5 hours
78 earthquakes
20 Nov
5 days 9 hours
57 earthquakes
5 Dec
5 days 18 hours
57 earthquakes
20 Dec
10 days 0 hours
135 earthquakes
2022
5 Feb
8 days 15 hours
147 earthquakes
19 May
21 days 19 hours
412 earthquakes
16 Jun
6 days 9 hours
74 earthquakes
19 Jul
22 days 3 hours
330 earthquakes
15 Sep
4 days 1 hours
55 earthquakes
3 Oct
5 days 4 hours
91 earthquakes
S20221016.1(10.4km)
15 Oct
5 days 23 hours
62 earthquakes
2024
15 Mar
2 days 2 hours
32 earthquakes
AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Seismic Swarm S20220408.1 in the Strait of Gibraltar

The Strait of Gibraltar marks the narrow marine passage separating the Iberian Peninsula from northwest Africa, situated at the convergent boundary between the Eurasian and African tectonic plates. This geodynamic setting drives moderate to occasional strong seismicity through a combination of oblique convergence, strike-slip faulting, and localized extension. The region forms part of the broader Gibraltar Arc, where the African plate moves northwestward relative to Eurasia at roughly 4–5 mm per year. Historical records document destructive events, including the 1755 Lisbon earthquake whose effects extended across the strait, and more recent moderate shocks in the 20th and 21st centuries.

Between 03:56 UTC on 7 April 2022 and 20:29 UTC on 5 May 2022, a seismic swarm comprising 392 events was recorded in the Strait of Gibraltar. The sequence lasted 688 hours and 33 minutes. Analysis of the first 100 events reveals predominantly low-to-moderate magnitudes, with the largest reaching 4.3. Depths ranged from near-surface values to approximately 34 km, consistent with crustal deformation along the plate-boundary zone. Early activity included several events above magnitude 3.0 within the first 24 hours, followed by a gradual decline in both frequency and peak magnitude while maintaining a steady background rate of smaller shocks.

The initial events clustered tightly in time and space, with magnitudes mostly between 1.8 and 3.1 and depths commonly 5–20 km. Subsequent activity through 11 April showed similar characteristics, punctuated by occasional events near 3.0 and one additional shock of 3.1. Depth distribution indicates both shallow crustal and slightly deeper sources, typical of the transitional tectonics in the area. No event in the examined subset exceeded magnitude 4.3, and the majority remained below 3.0, underscoring the swarm’s non-destructive nature despite its duration.

Since 1 January 2000, nine seismic swarms have been identified in the same region. Earlier episodes occurred in 2016 (one swarm) and 2021 (seven swarms), with the 2022 sequence representing the ninth. These recurrent swarms illustrate episodic strain release along the plate interface without producing a single dominant mainshock.

Such sequences are characteristic of the Strait of Gibraltar, where fluid migration and aseismic slip may interact with the complex fault network. Continued monitoring by regional networks remains essential for distinguishing swarm behavior from foreshock sequences that could precede larger events.

References

  • Instituto Geográfico Nacional (IGN) seismic catalog
  • United States Geological Survey (USGS) Earthquake Hazards Program
  • European-Mediterranean Seismological Centre (EMSC) regional reports