Puerto Rico: 24 Earthquake Swarms Recorded Within a Day and 447 since January

Earthquake swarms have continued in Puerto Rico recently.

In just one day, two dozen of earthquakes were detected in Puerto Rico, while hundreds of earthquakes were recorded since January.

There were no immediate reports of any significant impacts from these quakes.

Earthquake Swarms Continue in Puerto Rico

The United States Geological Survey (USGS) recorded 24 earthquakes in Puerto Rico in just one day from Feb. 10 to Feb. 11, and 447 earthquakes since January.

The USGS latest data shows that Puerto Rico remains seismically active.

The intensity of the recent earthquakes in Puerto Rico ranges between 3.1 and 4.3 magnitudes.

There were no immediate reports of casualties, infrastructural damage, or a tsunami warning. These indicate that despite the recurring earthquakes, their intensity is not strong enough to cause a significant impact.

However, there are reported accounts of people saying they felt shaking from these earthquakes.

Among the strongest of the earthquakes up to date, the 4.3 magnitude earthquake prompted the National Oceanic and Atmospheric Administration (NOAA) - U.S. Tsunami Warning System based in Honolulu, Hawaii, to issue a bulletin.

The bulletin issued by the NOAA - U.S. Tsunami Warning System stated there is no tsunami threat and confirmed people may have experienced a shaking effect from the earthquake.

Contestation between Aftershocks and Earthquake Swarms

The recurring earthquakes in Puerto Rico have been widely contested as to whether they are earthquake swarms or aftershocks from the January 2020 earthquake in Puerto Rico.

In December 2019, Puerto has been experiencing recurring earthquake swarms, 123 of these earthquakes had a magnitude of 3 or higher until a major earthquake the following year.

In January 2020, the island was struck by a 6.4 magnitude earthquake, resulting in multiple casualties and disruption.

Following the major earthquake in 2020, low-intensity earthquakes have continued in Puerto Rico until February 2022.

Amid the contestation of their classifications, these earthquakes in Puerto Rico reportedly fall under the definition of an earthquake swarm.

In the book Understanding Faults: Detecting, Dating, and Modeling published in 2020, an earthquake swarm is defined as short-lived and a sequence of multiple earthquakes that lasts within a short time period.

Earthquake swarms have no mainshock or tremor from an identifiable first earthquake.

Even short-lived earthquake swarms can last from hours, days, and even months, while aftershocks usually occur immediately following a main identifiable earthquake.

Furthermore, aftershocks can come in a sequence of many earthquakes.

The Caribbean and North American Tectonic Plates

There have been several explanations regarding the continuance of low-intensity yet recurring earthquakes in Puerto Rico.

However, some of these explanations were attributed to two tectonic plates which Puerto Rico is nearly sitting on.

According to the National Geographic, there has been an ongoing tectonic plates battle under Puerto Rico, which is located above the edge of the Caribbean tectonic plate.

The National Geographic explained that the said plate is continuously colliding with the North American plate.

Although Puerto Rico had a long history of earthquakes, the small quakes since December 2019 are unique and unusual. As a result, scientific inquiry and studies to explain the phenomenon are expected in the coming months.