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:
GOLFO DE FONSECA, HONDURAS
Period:
26 Jul 2023 18:25:51 - 2 Aug 2023 08:25:52 (6 days 14 hours)
Volcanoes in 100km radius:
Cosiguina(15km), Tigre, Isla del(20km), Zacate Grande, Isla(25km), Aramuaca, Laguna(69km), San Cristobal(74km), San Miguel(86km), Chinameca(94km), Telica(95km)
Earthquakes:
289
No swarms nearby.
AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Seismic Swarm Activity in Golfo de Fonseca, Honduras: July–August 2023 Event

A seismic swarm designated S20230726.1 was recorded in the Golfo de Fonseca region of Honduras. The sequence began at 18:25 on 26 July 2023 and concluded at 08:25 on 2 August 2023, spanning 158 hours and encompassing 289 earthquakes. This event represents the second swarm documented in the area since 2000, following one in 2022.

The Golfo de Fonseca lies at the tectonic boundary where the Cocos Plate subducts beneath the Caribbean Plate. This subduction zone drives frequent seismic activity throughout Central America. The gulf itself occupies a pull-apart basin influenced by strike-slip faulting along the Caribbean–Cocos margin, with regional faults accommodating oblique convergence. Shallow crustal seismicity is common, typically occurring at depths less than 20 km.

Analysis of the first 100 events reveals predominantly low-magnitude earthquakes ranging from 2.5 to 3.7. The strongest event reached magnitude 3.7 on 27 July at 04:36:24, with a focal depth of 7 km. Depths across the sequence clustered between 1 km and 17 km, with the majority between 3 km and 8 km, indicating shallow crustal sources. Temporal distribution showed the highest rates in the initial 24 hours, followed by a gradual decline, consistent with swarm behavior rather than a classic mainshock-aftershock sequence.

Geological records indicate that the broader Central American subduction system has produced significant historical earthquakes, including events in 1982 and 2009 that affected Honduras. The 2023 swarm aligns with background microseismicity patterns driven by ongoing plate motion at approximately 8–9 cm per year. No surface rupture or significant structural damage was associated with this low-magnitude activity.

The swarm’s shallow depths and clustered locations suggest fluid migration or stress triggering along local faults within the gulf’s sedimentary basin. Such sequences are characteristic of volcanic arcs and back-arc regions in subduction settings.

References

  • SeismoSight internal swarm classification S20230726.1
  • USGS Earthquake Catalog (historical regional data)
  • Central American Seismic Commission tectonic reports