At 08:29:09 EDT on 14 August 2021, a magnitude 7.2 earthquake struck the Tiburon Peninsula of southern Haiti. It had a 10-kilometre-deep (6.2 mi) hypocenter near Petit-Trou-de-Nippes, approximately 150 kilometres (93 mi) west of the capital, Port-au-Prince. Tsunami warnings were briefly issued for the Haitian coast. At least 2,248 people were confirmed killed as of 1 September 2021 and more than 12,200 injured, mostly in the Sud Department. An estimated 650,000 people were in need of assistance. At least 137,500 buildings were damaged or destroyed.
It is the deadliest earthquake and deadliest natural disaster of 2021. It is also the worst disaster to strike Haiti since the 2010 earthquake. UNICEF estimates more than half a million children were affected. The Haitian Civil Protection General Directorate (DGPC) warned of a possible large humanitarian crisis resulting from the earthquake. USAID provided US$32 million in foreign aid to Haiti for reconstruction efforts following the devastating earthquake. This earthquake had the most casualties of any disaster since the 2018 Sulawesi earthquake. The economic loss from this earthquake is estimated at over 1.5 billion US dollars, nearly 10% of the country's gross domestic product.
Haiti lies within the complex plate boundary zone between the North American plate to the north and the Caribbean plate to the south. This zone is interpreted to contain a number of microplates, particularly the Gonâve microplate, which is bounded to the north by the Septentrional-Oriente fault zone and to the south by the Walton fault zone and the Enriquillo–Plantain Garden fault zone, all of which are active left lateral transform faults. Although dominated by lateral motion the plate boundary zone also accommodates a component of north–south shortening. This has led to overall transpression along the main strike-slip faults. The largest earthquake in the region prior to the 2021 event was in 1952, and measured 6.2 magnitude, occurring 35 km to the west.
In the Tiburon Peninsula, the main structure is the Enriquillo–Plantain Garden fault zone, which runs along its length. This fault zone carries almost half of the left lateral displacement between the North American and Caribbean plates, with a displacement rate of about 7 mm per year. The epicentre of the 2010 Haiti earthquake was located at the eastern end of the peninsula and was caused by movement on previously unknown thrust faults that form part of the overall fault zone, without rupturing the main strike-slip fault strand. The same fault zone is thought to have been the source of the 1751 and 1770 earthquakes that destroyed the capital Port-au-Prince.
The earthquake occurred as a result of oblique-reverse faulting on an 80 km (50 mi) section of the Enriquillo–Plantain Garden fault zone, 125 km (78 mi; 67 nmi) west of the Haitian capital Port-au-Prince, consistent with its location and the observed focal mechanism. It had an estimated hypocentral depth of 10.0 km (6.2 mi).
Finite-fault inversion and back projection indicated an earthquake rupture on two separate strike-slip and reverse faults that are not connected to the main strand of the plate boundary fault. The initial rupture occurred on a blind thrust fault, but movement transitioned to left-lateral strike-slip faulting. The rupture jumped a restraining bend onto another strike-slip fault; both separate branches of the plate boundary fault, and previously unidentified. The rupture process of the earthquake indicate the highly oblique motion between the two tectonic plates. The restraining bend where the rupture jumped from a reverse fault to a strike-slip fault was located beneath Pic Macaya. The reverse fault, located east of the bend experienced an estimated maximum slip of 2.7 m (8.9 ft). The strike-slip fault produced up to 1.3 m (4.3 ft) of left-lateral displacement.
The earthquake produced significant afterslip in its aftermath. During the first four days, afterslip east of Pic Macaya released the energy equivalent to a Mw7.0 earthquake. Movement propagated to the surface three days after the mainshock.
Two weeks after the 2010 earthquake, a paper was published about coulomb stress transfer due to the event. The paper identified two sections east and west of the 2010 rupture which had accumulated significant strain as a result. The 2021 rupture may have been encouraged by the 2010 event due to stress transfer. Although it struck west of the 2010 rupture, a large seismic gap exists between the two events. It is thought that stresses on that section are still insufficient to trigger an earthquake rupture.
At least 900 aftershocks have been recorded following the mainshock, the strongest being Mw 5.8 in magnitude and centered approximately 65 kilometers further west on the Tiburon Peninsula. Additional tremors shook Les Cayes city on 19 August 2021. On 21 December, a 4.4 magnitude aftershock struck the area, causing further damage and injuring 150 people, most of them indirectly. On 24 January 2022, the same region was struck by two aftershocks, measuring 5.3 and 5.1 Mw, respectively. The aftershocks killed two people; one from a landslide in Fonds-des-Nègres, and the other in Anse-à-Veau by a collapsing wall. Fifty-two people were also injured. At least 191 houses were destroyed and 600 suffered damage in Nippes.
Interactive map of 2021 Haiti earthquake
According to the USGS PAGER service, the Modified Mercalli intensity scale (MMI) of the earthquake reached VII (Very Strong) in Les Cayes and MMI V (Moderate) in Port-au-Prince. The earthquake was also felt in Jamaica, where the intensity reached MMI IV (Light) in Kingston.
Widespread tsunami warnings were issued throughout the Caribbean, with waves up to 3 to 10 feet (1–3 metres) high initially expected to hit Port au Prince. The tsunami warning was later rescinded. The tsunami only reached 3 cm (0.098 ft) in height in that location.
At least 8,444 landslides were triggered across a 2,700 km2 (1,000 sq mi) area. A large portion (89.4 percent) of these reported landslides occurred on the hanging wall of the fault—particularly at Pic Macaya National Park which accounted for 72.2 percent of the total or 6,100 reports. The total area of these landslides was 45.6 km2 (17.6 sq mi). Landsliding was more widespread than compared to the 2010 earthquake.
The city of Les Cayes, Haiti's third-largest city, was the closest to the epicenter of the earthquake. The city suffered extensive damage including many collapsed homes, places of worship, and commercial buildings. According to the Haitian Civil Protection Agency, at least 37,300 or more homes were destroyed and 46,000 others were damaged as of 16 August. The Haitian Civil Protection General Directorate later reported that more than 60,700 homes have been destroyed and 76,100 others have sustained damages as of 18 August. There were also a number of hotels that were severely damaged or collapsed. At least 53 medical facilities suffered partial damage while six were totally destroyed. In addition to that, the quake damaged or destroyed 1,060 schools.
A report published by the Inter-American Development Bank estimated the total losses at US$1.6 billion, or 9.6% of Haiti's gross domestic product (GDP). The report stated that the estimate was based on a fatality figure of 2,500. The total damage cost range from US$1.5 to 1.7 billion.
The Immaculee Conception Church of Les Anglais, a historical landmark constructed in 1907, collapsed when the quake struck during a Mass. The collapse of the facade of the church killed 17 people. Two individuals trapped under the rubble were rescued by nearby construction workers. At Toirac village, just outside Les Cayes, 20 people died in the collapse of the St. Famille du Toirac church during a funeral Mass. In Marceline, a small town 30 minutes away from Les Cayes, the main Catholic church collapsed. Two women cleaning the church were killed. In the Les Cay Diocese, more than 220 Catholic places of worship were destroyed.