Structural damage after shallow M5.4 aftershock hits southern Puerto Rico

A shallow earthquake registered by the USGS as M5.4 hit southern Puerto Rico at 11:13 UTC (07:13 LT) on May 2, 2020. The agency is reporting a depth of 9 km (5.6 miles). The quake occurred at Tallaboa, with extensive damage reported on the island, including historical buildings in Ponce.

The USGS issued a green alert for shaking related fatalities and orange for economic losses — significant damage likely, disaster potentially widespread.

62 000 people are estimated to have felt very strong shaking, 120 000 moderate, and 1 941 000 light.

The epicenter of the tremor was located 6 km (3.7 miles) south of Tallaboa, also hitting Guanica and Guayanilla– the same areas that were struck by M6.4 quake on January 7, which was the strongest in an intense seismic swarm shaking area since December 29, 2019. 

USGS noted that this earthquake is an aftershock of the January tremor, and occurred as a result of the same tectonic activity. 

Puerto Rico earthquakes detected by USGS in 30 days to May 5, 2020. Credit: TW/SAM, Google

The event resulted in cracked walls, ravaged supermarket shelves, and collapsed second-story of a balcony in the southern coastal city of Ponce. Power was briefly disrupted on the island. There were no immediate reports of casualties. Much of the damage was in Ponce, where a museum and other historical buildings were affected.

Health Secretary Lorenzo Gonzalez called it "a crisis on top of another crisis" as the tremor occurred amid a two-month lockdown and just hours after the government announced the highest spike in COVID-19 cases since the first was reported in March.

About 50 families were forced to evacuate, however, governor Wanda Vasquez said that they will not be relocated in shelters due to coronavirus concerns. "We’re up against an emergency situation, but we can’t forget that the most lethal one we have in our hands is COVID-19," she said, urging people to wear protective equipment.

Guanica mayor Santos Seda reported no major damage in the area. "Thank God, everyone is okay," he said, adding that "the infrastructure is already weak."

On May 3, Ponce mayor Mayita Melendez said officials will keep doing rounds of damage assessment across the city. "We are going to keep everyone posted with updates on the current situation."

Puerto Rico's Seismic Network director Victor Huerfano stated that while it's understandable that people are shocked by the termor, it's not unusual given the seismic activity that started in the region earlier this year. "In the long run, it’s decreasing, but you can have peaks," he said, adding that strong aftershocks are expected to continue.  A series of less powerful shocks then followed the M5.4 quake, which ranged from M4.9 to 2.6.

Featured image credit: Mayita Melendez