Location:

Period:

11 Sep 2022 13:28:02 - 12 Sep 2022 22:49:23 (1 day 9 hours 21 minutes)

Volcanoes in 100km radius:

Cosiguina(21km), San Cristobal(46km), Tigre, Isla del(49km), Zacate Grande, Isla(54km), Telica(67km), Negro, Cerro(86km), Las Pilas-El Hoyo Complex(89km), Aramuaca, Laguna(97km)

Earthquakes:

2 swarms found nearby.

2022

S20220608.2(11.3km)

8 Jun

3 days 22 hours

55 earthquakes

2023

S20230726.1(29.3km)

26 Jul

6 days 14 hours

289 earthquakes

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Seismic Swarm S20220912.1: Activity Near the Nicaraguan Coast

A seismic swarm designated S20220912.1 occurred near the coast of Nicaragua between 13:28 on 11 September 2022 and 22:49 on 12 September 2022. In a span of 33 hours and 21 minutes, 29 earthquakes were recorded. Depths ranged primarily between 4 km and 14 km, with magnitudes between 2.5 and 4.3. The sequence featured two events reaching magnitude 4.3, occurring at 00:33 on 12 September (depth 4 km) and at 09:02 (depth 10 km). Other notable shocks included a magnitude 3.9 at 00:35 and several events of magnitude 3.0–3.7 distributed throughout the period.

The swarm began with a magnitude 2.7 event at 13:28 on 11 September at 7 km depth. Subsequent activity intensified overnight, with clusters around 00:32–01:52 and again near 07:00–10:00 on 12 September. Later events tapered off, concluding with a magnitude 2.6 shock at 22:49 on 12 September at 6 km depth. All events remained below damaging thresholds, consistent with typical swarm behavior where energy releases gradually rather than in a single mainshock-aftershock pattern.

Nicaragua lies along the Middle America Trench, where the Cocos Plate subducts beneath the Caribbean Plate at rates of approximately 8–9 cm per year. This convergent margin produces frequent shallow to intermediate-depth seismicity and hosts active volcanic chains. The September 2022 swarm occurred in an offshore segment of this subduction interface, a zone known for persistent low-to-moderate magnitude activity driven by plate coupling and fluid migration along the megathrust.

Historical records indicate that the region has experienced multiple large earthquakes, including the destructive 1972 Managua event and the 1992 tsunami-generating shock off the Nicaraguan coast. According to internal classification data maintained by SeismoSight, only one swarm has been identified in the area since 1 January 2000, making S20220912.1 the sole recorded swarm episode in that interval.

The shallow focal depths (mostly 4–10 km) suggest the activity occurred within the upper portion of the overriding plate or along the plate interface itself. Such swarms can reflect aseismic slip transients or localized increases in pore-fluid pressure, although no surface deformation or volcanic unrest was associated with this sequence.

Continued monitoring of the Nicaraguan margin remains essential given the tectonic setting. Swarms like S20220912.1 provide valuable data for refining models of subduction-zone behavior and improving regional seismic hazard assessments.

References SeismoSight internal swarm classification S20220912.1 USGS Earthquake Catalog and regional tectonic summaries Global CMT and Nicaraguan seismic network reports on subduction-zone activity