Seismic Swarm Near Antigua: 19 Earthquakes Recorded Over Three Days

The eastern Caribbean has experienced a significant earthquake swarm over the past three days, with 19 seismic events recorded in waters near Antigua and Barbuda, according to data from the University of the West Indies Seismic Research Centre (UWI SRC).

The three most recent earthquakes occurred near Antigua last night and early this morning. A magnitude 3.9 tremor struck at 10:04 pm on Tuesday just 52 kilometers north of Saint John’s—the closest any quake in this sequence has come to the capital. This was followed by a magnitude 3.8 earthquake at 12:13 am and a magnitude 4.1 at 2:42 am this morning, Wednesday, both located farther offshore in similar positions to Monday’s  events.

The sequence began on Monday, October 27, at 8:38 am local time with a powerful magnitude 6.7 earthquake centered approximately 264 kilometers east-southeast of Saint John’s, Antigua. The quake occurred at a relatively shallow depth of 12 kilometers beneath the ocean floor. This initial event was followed by several significant aftershocks, including a magnitude 6.1 earthquake just 17 minutes later at 8:55 am, a magnitude 5.2 at 8:46 am, and a magnitude 5.4 tremor at 9:26 am. Throughout Monday, the region experienced 17 earthquakes in total, ranging from magnitude 3.5 to 6.7, with most occurring between 8:38 am and 2:40 pm.

The majority of the earthquakes were clustered in an area approximately 220-280 kilometers from the major population centers of Point-à-Pitre, Guadeloupe; Roseau, Dominica; and Saint John’s, Antigua and Barbuda. The depths of these events varied from 10 to 47 kilometers, with most occurring between 12 and 40 kilometers beneath the seafloor.

The UWI Seismic Research Centre has issued preliminary locations for all events, with most receiving manual verification by SRC analysts. The organization has encouraged anyone who felt these earthquakes to report their experiences through their feedback system. All preliminary locations carry the standard disclaimer that they were calculated by computer algorithms and remain subject to potential revisions pending further evaluation.

The eastern Caribbean sits along the boundary between the North American and Caribbean tectonic plates, making it one of the most seismically active regions in the Americas. Earthquake swarms—clusters of seismic events occurring in a specific area over a short time period—are not uncommon in this region, though a sequence beginning with a magnitude 6.7 event is particularly notable.

Residents across Antigua and Barbuda, Guadeloupe, Dominica, and neighboring islands are advised to remain alert and follow guidance from local emergency management authorities as the situation continues to develop.