Starting on December 28, 2019,Puerto Rico residents fear aftershocks after deadly 6.4 magnitude earthquake. David Begnaud. CBS NEWS. January 7, 2020. Retrieved January 31, 2020. and progressing into 2020, the southwestern part of the island of Puerto Rico was struck by an earthquake swarm,Magnitude 5.9 earthquake rocks Puerto Rico and causes landslide in Peñuelas. Grace Hauck. USA Today. January 11, 2020. Retrieved January 14, 2020. including 11 that were of magnitude 5 or greater. The largest and most damaging of this sequence was a magnitude 6.4 , which occurred on January 7 at 04:24 AST (08:24 UTC), with a maximum felt intensity of VIII (Severe) on the Modified Mercalli intensity scale. At least one person was killed, and several others were injured. A 5.8 earthquake the previous day caused the destruction of a natural arch, a tourist attraction at Punta Ventana in Guayanilla. A 5.9 aftershock on Saturday, January 11, damaged many structures, including several historical buildings as well as modern high-rises in the city of Ponce.Experts seek answers behind constant quakes in Puerto Rico. Danica Coto. The Associated Press. January 14, 2020. Retrieved January 14, 2020.
Power was lost island-wide immediately after the quake and was increasingly restored over a period of a week. Damage to homes was extensive and, by January 14, more than 8,000 people were homeless and camping outdoors in various types of shelters, with 40,000 others camping outside their homes, just in the city of Ponce alone.Cifra parcial de refugiados asciende a más de 8,000. Osman Pérez Méndez Primera Hora. January 14, 2020. Retrieved January 14, 2020. There were refugees in 28 government-sponsored refugee centers spread over 14 municipalities of southern and central Puerto Rico.4,924 personas ubicadas en 28 refugios. Accessed January 14, 2020. Damage to government structures was calculated in the hundreds of millions and financial losses were estimated in $3.1 billion. A power plant that supplied over a quarter of Puerto Rico's energy needs was badly damaged and was shut down, with repairs estimated to take at least a year.
The day of the mainshock, January 7, Puerto Rico governor Wanda Vázquez Garced declared a state of emergency and activated the Puerto Rico National Guard and the Puerto Rico State Guard. That same day, she also made available $130 million in aid to the municipalities affected. The White House also approved $5 million in federal emergency relief.La declaración de emergencia de Donald Trump tiene un límite de $5 millones: FEMA confirma que en espera de una declaración de desastre, su intervención tiene por el momento un tope financiero. El Nuevo Dia. Guaynabo, Puerto Rico. January 13, 2020. Retrieved January 13, 2020. On January 12, the day after the January 11, 5.9 aftershock, the governor distributed $12 million to six municipalities most affected by the quake.Cerca de 5,000 refugiados a casi una semana del terremoto del 7 de enero. Agencia EFE. January 13, 2020. Retrieved January 13, 2020.Wanda Vázquez entrega cheque de $2 millones a municipios del sur afectados por el terremoto: Los pueblos de Ponce, Yauco, Guánica, Guayanilla, Peñuelas y Utuado podrán usar los fondos inmediatamente. Accessed January 13, 2020. Tent cities were set up in five of the hardest-hit towns with space for some 3,200 refugees.
Tectonic setting Puerto Rico lies at the highly oblique convergent boundary between the Caribbean plate and the North American plate. A separate Puerto Rico–Virgin Islands microplate has been identified based on GPS observations. To the north the North American plate is being subducted beneath this microplate along the Puerto Rico Trench. To the south of Puerto Rico the microplate is being thrust southwards over the Caribbean plate along the Muertos Thrust system. On the upper slope and shelf the current style of faulting is extensional with a series of WSW-ENE trending normal faults, such as the Ponce Fault and the Bajo Tasmanian Fault. Several faults are also known to cross parts of the main island.
Earthquake sequence
The sequence began on December 28, 2019, with a 4.7 earthquake, followed closely by a 5.0 event in the early hours of December 29. Several earthquakes of M <5 occurred over the next few days, followed by a 5.8 event at 10:32 UTC on January 6. The largest event, a 6.4, occurred the next morning, followed by a 5.6 event within 10 minutes and a 5.0 about 15 minutes after that. The 6.4 event had a focal mechanism consistent with normal faulting on a fault trending WSW-ENE. A 5.9 event was then logged on January 11 at 12:54 UTC. In the first month of the sequence there were a total of 11 M ≥5 earthquakes and a further 82 in the range M 4–4.9. A 5.4 earthquake occurred on May 2 at 11:13 UTC in the same area as the M 6.4 event and with a similar focal mechanism. As of May 2, after a further two M>4 shocks in the same area, the total number of earthquakes in the sequence of M>3 exceeded 1,000 and there had been 95 of M>4. Sequence of notable earthquakesDateUTCMwMMIDepth (km)Ref.EpicenterDecember 2901:06:005.0V6.0Guánica, offshoreJanuary 610:32:185.8VI6.0Guayanilla, offshoreJanuary 708:24:276.4VIII6.0Guayanilla, offshoreJanuary 708:29:495.0IV10.0Peñuelas, offshoreJanuary 708:34:015.6V10.0Peñuelas, offshoreJanuary 708:50:455.0V10.0Ponce, offshoreJanuary 711:18:435.6VI9.0Magas, GuayanillaJanuary 1022:26:255.2VI9.0Guánica, offshoreJanuary 1112:54:455.9VII5.0Guayanilla, offshoreJanuary 1112:56:225.2VI10.0Guayanilla, offshoreJanuary 1515:36:235.2V5.0Lajas, offshoreJanuary 2520:20:385.0V13.0Indios, GuayanillaFebruary 414:45:555.0V7.0Guánica, offshoreMay 211:13:185.4VII9.0Peñuelas, offshoreJuly 320:49:455.3VI3.0Lajas, offshoreUnited States Geological Survey
Response
Puerto Rico governor Wanda Vázquez Garced declared a state of emergency on January 7 and mobilized the Puerto Rico National Guard. On January 8, the day after the main quake, the Ponce municipal government registered 1,111 residents in city shelters, "not including hundreds more" who drove to government-designated meeting sites, such as Estadio Paquito Montaner, to sleep in their cars. The parking lot at Auditorio Juan Pachin Vicens was also used as a meeting site. The Bernardino Cordero Bernard Vocational High School was also used as a shelter. The night after the quake, it was estimated that over 40,000 Ponce residents chose to sleep in their cars instead of their homes out of fear of more quakes. By January 13 the number of refugees was estimated at 3,000 Island-wide, but the municipal officials of some local governments believed that figure was probably about right for refugees in just their own single municipalities. Another estimate out the number of refugees at 5,000.Barbra Streisand comenta el bloqueo de Trump a los fondos para Puerto Rico. Miguel Diaz. EsNoticia. Ponce, Puerto Rico. January 13, 2020. Retrieved January 13, 2020.
On January 7, the Puerto Rican government made available $130 million in aid. Late January 7, FEMA confirmed that US president Donald Trump had issued a (non-disaster) emergency declaration with a $5 million cap. The $5 million emergency declaration monies were to be spent on emergency services only.Hit by devastating earthquakes, Puerto Rico still waiting on billions for hurricane relief: Pelosi calls on administration to ‘cease and desist’ its ‘unlawful’ withholding of funds. Erica Werner. The Washington Post. January 9, 2020. January 12, 2020. On January 12, 2020, Puerto Rico governor Wanda Vázquez Garced made a disbursement of $2 million to each of six municipalities most affected by the quake; the money came from the Puerto Rico State Emergency Reserve Fund. The government set up a central command center, where all pertinent state and municipal dependencies supporting the relief effort were to set up base and coordinate activities at the Polideportivo Frankie Colon in Urbanización Los Caobos, Barrio Bucaná, Ponce. It also became a collection center for items for the earthquake homeless.COE en Ponce servirá como centro de acopio para recibir donaciones. Cyber News. January 12, 2020. Retrieved January 22, 2020.
By January 14, over 600 soldiers of the Puerto Rico National Guard had set up five tent cities for the homeless, with at least some tents outfitted with air conditioning for the bed-ridden and the elderly, in the municipalities of Guánica, Yauco, Guayanilla, Peñuelas and Ponce, with facilities for over 3,200 refugees.Abrió en Guánica primer campamento militar para víctimas del terremoto. Bárbara J. Figueroa Rosa January 14, 2020. Retrieved January 22, 2020.
Effects
Human losses A male resident of Urbanización Jardines del Caribe, in the city of Ponce, lost his life as a direct result of the January 7 quake; additionally, eight other people in the area were injured.6.4 magnitude earthquake strikes Puerto Rico, injuring eight people: Strong quake followed by an aftershock measuring 6.0, Heavy damage in some areas. The Guardian. Associated Press. January 7, 2020. Retrieved January 9, 2020. A woman died of a heart attack in the town of Guayanilla, after a 4.36-magnitude overnight aftershock occurred, on the night of January 9 into January 10.Puerto Ricans in earthquake shelters refuse to go home. Dánica Coto. Associated Press. January 10, 2020. Retrieved January 12, 2020. By January 10, two additional people had died of different medical conditions, attributed to the effects of the earthquakes.As Lights Flicker On After Puerto Rico Earthquake, Officials Say 3 More Have Died. The New York Times. January 10, 2020. Retrieved January 13, 2020.
Homeless
There were refugees in 28 government-sponsored refugee centers in the southern and central Puerto Rico municipalities of Yauco, Guánica, Ponce, Peñuelas, Guayanilla, Utuado, Maricao, Juana Díaz, Adjuntas, Sabana Grande, San Germán, Lajas, Jayuya and Mayagüez. The quakes also caused 28 families in Lares to lose their homes. At least three residential high-rise buildings in Ponce were rendered unusable, leaving the residents homeless. Michelle Estrada Torres. Voces del Sur. Ponce, Puerto Rico. January 14, 2020. Retrieved January 22, 2020.
On January 13, it was reported that some 3,000 homes had been destroyed or significantly damaged.Cerca de 5,000 refugiados a casi una semana del terremoto del 7 de enero. Dánica Coto, Associated Press. Agencia EFE. January 13, 2020. Retrieved January 13, 2020. By January 14, the number of homeless region-wide had climbed to 8,000.Cifra parcial de refugiados asciende a más de 8,000: El secretario de Estado admitió que “no tenemos el número de personas durmiendo en las aceras” y podrían ser miles más. Osman Pérez Méndez. January 14, 2020. Retrieved January 22, 2020. A January 15, 2020, register of homes rendered uninhabitable listed at least 789 properties.Al menos 789 casas afectadas por los temblores de tierra. Cyber News. Retrieved January 22, 2020. The number of homes with some level of damage was, however, significantly higher. For example, according to its mayor, in the municipality of Yauco alone, there were 3,200 homes with some degree of damage.Sismos en el sur: Pasan terrible factura emocional y estructural en Yauco y Ponce: El alcalde de Yauco, Ángel Luis Torres Ortiz, indicó que unas 3,200 unidades de vivienda en su municipio sufrieron daños a raíz de la actividad sismica de la pasada semana. Jason Rodríguez Grafal. January 15, 2020. Retrieved January 22, 2020.