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Location:
CANARY ISLANDS, SPAIN REGION
Period:
4 Aug 2011 16:47:17 - 6 Aug 2011 12:01:42 (1 day 19 hours 14 minutes)
Volcanoes in 100km radius:
Hierro(5km), La Palma(92km)
Earthquakes:
41
9 swarms found nearby.
2011
22 Jul
21 hours
25 earthquakes
7 Aug
3 days 8 hours
64 earthquakes
12 Sep
1 day 10 hours
32 earthquakes
S20110927.2(13.6km)
26 Sep
11 days 23 hours
305 earthquakes
2012
VS20120625.1(12.3km)
24 Jun
6 days 12 hours
345 earthquakes
S20120702.1(12.2km)
2 Jul
8 days 13 hours
183 earthquakes
14 Sep
3 days 1 hours
53 earthquakes
2013
18 Mar
23 hours
29 earthquakes
S20130322.1(24.1km)
21 Mar
10 days 6 hours
476 earthquakes
AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Seismic Swarm S20110805.1 in the Canary Islands Region

The seismic swarm designated S20110805.1 occurred in the Canary Islands, Spain, from 16:47 on 4 August 2011 to 12:01 on 6 August 2011. Over 43 hours and 14 minutes, the sequence produced 41 earthquakes. All events registered magnitudes between 1.3 and 2.3 and originated at shallow depths of 7 to 18 km, with the majority clustered near 10–11 km.

The sequence began with a magnitude 1.8 event at 10 km depth. Subsequent shocks maintained low magnitudes, rarely exceeding 2.0, and showed no pronounced migration in depth. Peak activity included two magnitude 2.1 events and one magnitude 2.3 shock on 5 August, all near 11 km depth. The final recorded event reached magnitude 1.9 at 7 km depth.

Such swarms commonly reflect fluid migration or minor magmatic movement within volcanic systems rather than tectonic fault slip. In the Canary Islands, the archipelago formed through hotspot volcanism on the African plate, producing a chain of basaltic shield volcanoes. Seismic sequences in this setting frequently precede or accompany intrusive episodes, as documented during unrest at El Hierro in 2011 and the 2021 La Palma eruption.

The shallow focal depths recorded in the 2011 swarm align with the typical brittle–ductile transition zone beneath the islands, where magma or hydrothermal fluids interact with the crust. No surface deformation or eruptive activity was associated with this particular sequence, consistent with many non-eruptive swarms observed in the region.

Overall, the event illustrates the persistent low-level seismic background that characterizes the Canary volcanic province. Continued monitoring of similar swarms remains essential for distinguishing intrusive unrest from background activity in this geologically active archipelago.

References

  • Instituto Geográfico Nacional (IGN), Spain – Seismic catalog and volcanic monitoring reports.
  • Geological Survey of Spain (IGME) – Regional volcanic geology summaries.
  • Global Volcanism Program, Smithsonian Institution – Canary Islands eruptive history.