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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:
1 km S of Indios, Puerto Rico
Period:
20 Mar 2025 05:23:15 - 26 Mar 2025 04:37:34 (5 days 23 hours 14 minutes)
Volcanoes in 100km radius:
None
Earthquakes:
70
20 swarms found nearby.
2018
S20181215.1(13.2km)
14 Dec
4 days 6 hours
109 earthquakes
2019
S20191229.1(11.1km)
28 Dec
244 days 6 hours
9147 earthquakes
2020
S20200107.1(17.7km)
7 Jan
1 day 21 hours
53 earthquakes
S20200502.3(14.8km)
1 May
2 days 18 hours
36 earthquakes
6 Oct
22 days 9 hours
229 earthquakes
S20201118.1(13.4km)
17 Nov
35 days 20 hours
447 earthquakes
S20201224.1(14.5km)
23 Dec
46 days 11 hours
2842 earthquakes
2021
S20210108.1(27.0km)
7 Jan
13 days 20 hours
148 earthquakes
29 Jan
2 days 1 hours
29 earthquakes
24 Jun
6 days 15 hours
127 earthquakes
S20210718.1(29.9km)
17 Jul
3 days 1 hours
37 earthquakes
2022
1 Feb
37 days 20 hours
630 earthquakes
21 Mar
19 days 5 hours
207 earthquakes
S20220424.1(17.7km)
23 Apr
17 days 11 hours
189 earthquakes
S20220806.1(14.6km)
5 Aug
13 days 6 hours
262 earthquakes
2023
S20230315.1(13.7km)
14 Mar
6 days 9 hours
92 earthquakes
S20230409.1(15.9km)
8 Apr
10 days 15 hours
189 earthquakes
30 Sep
3 days 22 hours
63 earthquakes
23 Oct
1 day 13 hours
25 earthquakes
2025
12 Mar
4 days 6 hours
74 earthquakes
AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Earthquake Swarm S20250320.3: Seismic Activity South of Indios, Puerto Rico

An earthquake swarm designated S20250320.3 occurred 1 km south of Indios, Puerto Rico, from 05:23 on 20 March 2025 to 04:37 on 26 March 2025. Over 143 hours and 14 minutes, the sequence registered 70 earthquakes. Magnitudes ranged from 1.6 to 4.4, with the majority between 2.0 and 2.6. Depths clustered primarily between 10 km and 18 km, consistent with shallow crustal seismicity in the region.

The swarm initiated with a magnitude 2.1 event at 14 km depth. Activity intensified rapidly, culminating in the largest event—a magnitude 4.4 earthquake at 13 km depth—followed by numerous aftershocks within minutes. Subsequent events maintained moderate energy release, including a magnitude 3.4 on 21 March and a magnitude 3.0 on 22 March. The sequence tapered gradually, ending with a magnitude 2.4 event at 14 km depth.

Puerto Rico lies at the complex tectonic boundary between the North American and Caribbean plates. The island experiences both subduction-related and strike-slip faulting along the Puerto Rico Trench to the north and the Muertos Trough to the south. This setting produces frequent seismic swarms, often linked to fluid migration or stress redistribution along regional faults. Historical records show elevated swarm frequency since 2000, with 20 documented episodes through 2025. Prior swarms occurred in 2018 (1), 2019 (1), 2020 (5), 2021 (4), 2022 (4), 2023 (4), and 2025 (1).

Such sequences typically last from hours to days and rarely produce significant damage when magnitudes remain below 5.0. Depths in this swarm align with the brittle upper crust, where most Puerto Rico seismicity nucleates. No surface rupture or notable ground deformation has been associated with comparable past events.

Ongoing monitoring by regional seismic networks continues to track aftershock decay and potential migration of activity. The 2025 swarm reinforces the persistent seismic hazard in southern Puerto Rico and underscores the value of real-time swarm classification for public awareness.

References

SeismoSight internal swarm classification S20250320.3
USGS Earthquake Catalog for Puerto Rico regional tectonics