Location:

Period:

18 Jul 2023 06:40:52 - 31 Jul 2023 03:48:43 (12 days 21 hours 7 minutes)

Volcanoes in 100km radius:

Cosiguina(83km), San Miguel(87km), Aramuaca, Laguna(88km), Usulutan(89km), Taburete(92km), Chinameca(93km), Tigre, El(93km), Tigre, Isla del(97km), Tecapa(98km)

Earthquakes:

265

2 swarms found nearby.

2001

PS20010115.1(71.4km)

14 Jan

2 days 2 hours

9 earthquakes

2012

PS20120827.1(68.1km)

27 Aug

1 day 4 hours

7 earthquakes

AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Seismic Swarm S20230719.1 Offshore El Salvador: July 2023 Overview

El Salvador lies along the Pacific Ring of Fire at the convergent boundary where the Cocos Plate subducts beneath the Caribbean Plate. This subduction zone, part of the Middle America Trench, drives persistent seismic and volcanic activity across Central America. Convergence rates average 7–9 cm per year, generating frequent earthquakes at varying depths as the oceanic slab descends. Offshore El Salvador experiences both shallow crustal events and deeper intraslab seismicity, with historical records documenting destructive quakes in 1986 and 2001.

Between 18 July and 31 July 2023, seismic monitoring recorded Swarm S20230719.1 offshore El Salvador. The sequence began at 06:40 UTC on 18 July and concluded at 03:48 UTC on 31 July, spanning 309 hours and 7 minutes. A total of 265 earthquakes were detected during this period. Analysis of the first 100 events shows magnitudes ranging from 2.5 to 4.2, with the majority between 2.7 and 3.9. Focal depths clustered between 20 km and 64 km, indicating activity within the subducting slab and overlying crust. The largest events reached magnitude 4.2 on 19 July at 00:26 UTC (33 km depth) and magnitude 4.1 on 19 July at 05:00 UTC (28 km depth). Event frequency peaked in the initial 24 hours, followed by a gradual decline while maintaining a steady low-magnitude background rate.

Such earthquake swarms differ from typical mainshock-aftershock sequences by lacking a single dominant event. Instead, they reflect distributed stress release, often linked to fluid migration or slow slip along the plate interface. In the Salvadoran offshore setting, similar patterns have been noted in prior episodes catalogued since 2000. Only two earlier swarms appear in the record: a single swarm in 2001 and another in 2012. These limited occurrences underscore the relatively infrequent but recurrent nature of swarm activity in this segment of the subduction zone.

The July 2023 swarm did not produce reported damage or tsunami alerts, consistent with its moderate magnitudes and offshore location. Continued monitoring remains essential given the tectonic setting’s capacity for larger events. Regional seismic networks, including those operated by El Salvador’s Ministerio de Medio Ambiente y Recursos Naturales, integrate data from regional and global stations to track such activity in real time.

References:
USGS Earthquake Catalog
Global CMT Catalog
Servicio Nacional de Estudios Territoriales de El Salvador (SNET) annual seismic reports