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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:
5 km SW of Guánica, Puerto Rico
Period:
8 Apr 2023 15:03:47 - 19 Apr 2023 06:56:52 (10 days 15 hours 53 minutes)
Volcanoes in 100km radius:
None
Earthquakes:
189
20 swarms found nearby.
2018
S20181215.1(26.1km)
14 Dec
4 days 6 hours
109 earthquakes
2019
28 Dec
244 days 6 hours
9147 earthquakes
2020
S20200107.1(12.6km)
7 Jan
1 day 21 hours
53 earthquakes
1 May
2 days 18 hours
36 earthquakes
S20201007.2(18.4km)
6 Oct
22 days 9 hours
229 earthquakes
17 Nov
35 days 20 hours
447 earthquakes
23 Dec
46 days 11 hours
2842 earthquakes
2021
S20210108.1(12.7km)
7 Jan
13 days 20 hours
148 earthquakes
S20210130.1(13.5km)
29 Jan
2 days 1 hours
29 earthquakes
24 Jun
6 days 15 hours
127 earthquakes
S20210718.1(14.3km)
17 Jul
3 days 1 hours
37 earthquakes
2022
1 Feb
37 days 20 hours
630 earthquakes
S20220322.1(10.8km)
21 Mar
19 days 5 hours
207 earthquakes
23 Apr
17 days 11 hours
189 earthquakes
S20220806.1(10.4km)
5 Aug
13 days 6 hours
262 earthquakes
2023
14 Mar
6 days 9 hours
92 earthquakes
S20231001.1(10.2km)
30 Sep
3 days 22 hours
63 earthquakes
S20231024.1(10.1km)
23 Oct
1 day 13 hours
25 earthquakes
2025
S20250312.1(14.3km)
12 Mar
4 days 6 hours
74 earthquakes
S20250320.3(15.9km)
20 Mar
5 days 23 hours
70 earthquakes
AI-generated article — for informational and entertainment purposes only. May contain inaccuracies. Full disclaimerFound an error?

Seismic Swarm S20230409.1 Near Guánica, Puerto Rico

Seismic swarm S20230409.1 was recorded 5 km southwest of Guánica, Puerto Rico. Activity began at 15:03 on 8 April 2023 and concluded at 06:56 on 19 April 2023, spanning 255 hours and 53 minutes. A total of 189 earthquakes were registered during this period. Analysis of the first 100 events reveals magnitudes between 1.3 and 4.5, with the majority falling in the 1.5–2.9 range. Depths concentrated between 5 km and 17 km, indicating shallow crustal sources typical of the region’s tectonic setting. The largest event reached magnitude 4.5 at 13:08 on 9 April at a depth of 13 km. Subsequent notable shocks included several magnitude 3.2 events on 9 and 10 April. Event frequency was highest in the first 48 hours, with clusters of low-magnitude aftershocks persisting through 12 April. Puerto Rico occupies a complex tectonic boundary between the North American and Caribbean plates. The island experiences both subduction-related seismicity along the Puerto Rico Trench to the north and strike-slip faulting associated with the Septentrional-Oriente fault system and the Muertos Trough to the south. Southwestern Puerto Rico, including the Guánica area, lies near the transition between these regimes, where east-west trending faults accommodate regional strain. This setting produces frequent earthquake swarms and occasional moderate mainshock-aftershock sequences. Since 1 January 2000, sixteen swarms have occurred in the monitored area. Annual counts are as follows: one each in 2018 and 2019, five in 2020, four in 2021, four in 2022, and one in 2023. The 2020 sequence, centered near the same region, remains the most significant recent precedent in both duration and cumulative energy release. Ongoing monitoring by regional seismic networks continues to track microseismicity in southwestern Puerto Rico. Such swarms provide valuable data for refining fault models and assessing short-term seismic hazard in this tectonically active zone.

References

USGS Earthquake Catalog (queried April 2023)
Puerto Rico Seismic Network, University of Puerto Rico at Mayagüez
Tectonic summary for the Caribbean region, USGS Professional Paper series