The Caribbean region has the potential to generate large, destructive earthquakes. Unfortunately for the people of Haiti, still recovering from the 2010 Mw 7.0 earthquake, another massive quake struck approximately 80 miles west of the capital, Port-au-Prince, on August 14, 2021—an area additionally recovering from Hurricane Matthew in 2016 and in the midst of the COVID-19 pandemic. The Mw 7.2 quake was felt in Jamaica, 200 miles away; more than 2,000 people reportedly died, at least 12,000 were injured, and extensive damage was caused to buildings, roads, and infrastructure.
How Do the 2010 and 2021 Quakes Compare?
The August 14 earthquake occurred on the Enriquillo-Plantain Garden Fault (EPGF) along the Tiburon Peninsula at a shallow depth of ~10 km. Historically, the largest earthquake to occur on the EPGF was an Mw 7.5 in 1770 with an epicenter located only 30 km east of the 2021 event. Various researchers have suggested recurrence times for an earthquake of Mw 7.2-7.5 on the western segment of the EPGF of ~250 years based on historical earthquakes, slip rate information, GPS rates, etc. (ten Brink et al. 2011, Bakun et al. 2012, Calais 2016), consistent with an earthquake this year.
With only a decade since the last large earthquake in Haiti, many are drawing comparisons between the 2010 and 2021 events. The 2021 earthquake ruptured a western segment of the EPGF while the 2010 earthquake ruptured a previously unknown blind thrust fault, the Leogane fault, which is located east of the recent 2021 rupture. Scientists have suggested, however, that the Leogane fault is part of the larger EPGF system and that deformation along this fault impacts the strain accumulation along the EPGF (e.g., Hayes et al. 2012). Therefore, we cannot preclude that the stress released by the rupture in 2010 did not alter the stress distribution on the western portion of the fault. Initial models suggest that the 2021 rupture propagated westward from the epicenter (e.g., USGS finite-fault model). Some preliminary analyses, in fact, suggest the 2010 and 2021 earthquakes may be part of a westward progressive earthquake sequence, although there are regions along the eastern portion of the EPGF near Port-au-Prince that remain highly stressed as well (Stein et al. 2021).
Damage and Destruction
Damage has been reported in 11 communes of Nippes department where the epicenter of the earthquake was located. Preliminary estimates indicated that more than 50,000 homes were destroyed and 70,000 damaged. In addition, critical facilities such as health centers have also experienced substantial damage or were destroyed when they were needed most. Sud, Nippes, and Grand’Anse departments, particularly the cities of Les Cayes, Jérémie, and Anse à Veaux are the most affected, suffering significant damage or destruction of property and critical infrastructure.
The August 14 earthquake adds trauma to a region experiencing political, social, and economic turmoil in addition to the COVID-19 pandemic, and still in recovery from past natural catastrophes. To make matters worse, the effects of Tropical Depression Grace on August 16 significantly hampered the rescue efforts. Following heavy rainfall, for example, the major national highway between Jérémie and Les Cayes was blocked due to landslides. After a magnitude 7.2 mainshock, aftershocks will occur, decreasing in frequency and severity for months, or possibly for years. Many, particularly in the first few weeks after the mainshock, are likely to be powerful enough to be felt and may cause additional damage to weakened structures.
Managing Caribbean Earthquake Risk
Earthquakes such as this highlight the need to manage the risk in this highly active, complex seismic region. The updated AIR Earthquake Model for the Caribbean delivers an integrated view of loss from ground shaking, liquefaction, and tsunami for 29 countries, including Haiti. The model incorporates the latest paleoseismological data and provides a time-dependent view of seismicity that accounts for the buildup of strain on large, well-studied faults over time, offering the most realistic view of seismic hazard available for the region. Combined with detailed industry exposure databases, the model delivers a comprehensive view of Caribbean earthquake risk necessary for effective risk management.
Bakun, W.H., Flores, C.H. and U. S. ten Brink (2012). Significant Earthquakes on the Enriquillo Fault System, Hispaniola, 1500-2010: Implications for Seismic Hazard, Bull. Seism. Soc. Am. 102 (1) 18-30.
Calais, E. (2016). Science et société dans la post-urgence du séisme du 12 javier 2010 en Haïti, Geologues, 188.
Hayes, G.P., Briggs, R.W., Sladen, A., Fielding, E.J., Prentice, C., Hudnut, K., Mann, P., Taylor, F.W., Crone, A.J., Gold, R., Ito, T. and M. Simons (2021). Complex rupture during the 12 January 2010 Haiti earthquake, Nature Geoscience, doi:10.1038/NGEO977.
ten Brink, U.S., Bakun, W.H. and C.H. Flores (2011). Historical perspective on seismic hazard to Hispaniola and the northeast Caribbean region, J. Geophys. Res. 116 (B12318), doi:10.1029/2011JB008497.
Stein, R.S., Toda, S., Lin, J., Sevilgen, V., 2021, Are the 2021 and 2010 Haiti earthquakes part of a progressive sequence?, Temblor.