- The earthquake is one of Puerto Rico’s strongest since the 7.1 magnitude San Fermín quake in 1918.
- At least one person has died, and hundreds of others are displaced.
- An expert with the Puerto Rico Seismology Network explains to Changing America why the island has experienced so many earthquakes lately.
The 6.4 earthquake that struck Puerto Rico early Tuesday morning appears to have been one of the island’s strongest since the San Fermín earthquake of 1918, which killed 116 people.
The island is currently recovering from the early-morning quake, which killed at least one person and damaged churches, schools and shops. The region is experiencing widespread power outages, leaving up to 346 people displaced from the Guánica county on the southern coast of the island.
“Puerto Rico has not faced a situation like this in 102 years,” Gov. Wanda Vásquez said in a press conference.
Although this is one of the strongest quakes, it comes after almost a month of tremors in the region. The National Geographic Survey states that Puerto Rico has seen about 400 low-magnitude earthquakes since late December.
Although this sounds alarming, it is actually routine, according to Elizabeth Vanacore of the Puerto Rico Seismology Network.
Vanacore says that the seismic activity Puerto Rico has seen for ages is due to the Puerto Rico Trench, a fault zone north of it and the U.S. Virgin Islands. The North American plate slides under the Caribbean plate, which creates pressure on both sides of the fault and causes one to snap. This all eventually leads to an earthquake.
Similar environments exist in Japan, Alaska and New Zealand, according to Vanacore.
Despite the natural explanation for frequent quakes, Vanacore said that what “we are currently observing is the first time we are experiencing this level of activity” — in terms of both earthquake magnitude and frequency.
She does note, however, that the records kept by the Puerto Rico Seismic Network only date back to 1986, and that there is ample evidence suggesting swarms of earthquakes like these have occurred hundreds of years before.
In 2018, for instance, Vanacore said that “the Puerto Rico Seismic Network recorded 4,000 events in our area of authority which is both Puerto Rico and the U.S. Virgin Islands.”
In recent cases, the quakes are very shallow and near the shore, and a large portion of them is being felt by the public, Vanacore added.
While other natural disasters, like the raging fires in Australia and California, can be attributed to climate change, Vanacore says that earthquakes are separate events.
The next step in understanding why Puerto Rico is so susceptible to swarms of earthquakes would be to observe the various faults around the island. Vanacore suspects an extension of the Punta Montalva fault or another unknown fault in the region.
She states that it will require more study to determine which fault is primarily responsible and how many are at play.
When asked about any future events like another major quake or tsunami, Vanacore says: “The only thing really predictable is that they’re unpredictable.”
While she cannot confirm a tsunami or another destructive quake is forthcoming, Vanacore stated that she had never seen a tsunami before in her career. She does primarily expect a series of aftershocks following the major event.
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