The 7.2-magnitude earthquake that struck the south of Haiti on 14 August 2021 is reminiscent of the devastating event of similar magnitude on 12 January 2010, which caused tens of thousands of deaths in the Léogâne – Port-au-Prince region and had severe economic consequences. The recent earthquake has led to significant loss of life and major damage, and was felt throughout the country as well as in the Dominican Republic and Cuba. It was recorded by Ayiti-Seismes, a citizen seismological network. The recorded data has been used for initial analysis by researchers at LMI CARIBACT.

LMI CARIBACT is an international joint laboratory financed by IRD. It is a partnership project between the URGéo laboratory of the Faculty of Sciences of the State University of Haiti and the French laboratory Géoazur (University and Observatory of the Côte d’Azur, CNRS, IRD).

Currently available data indicates that the epicentre of the main shock was in the southern province of Nippes, around 10 km east of Baradères and 20 km southwest of Anse à Veau.

The epicentre of the earthquake on 14 August 2021 was located in a region with particularly high seismic activity in Haiti's southern peninsula. The Anse à Veau region was previously hit by a strong earthquake on 8 April 1860 and then again on 27 October 1952, when another earthquake caused the death of at least six people and significant material damage. This quake was followed by an aftershock of magnitude 5.7 on 25 January 1953. The same region was also hit by a smaller seismic crisis in September and October 2015.

It is possible that the earthquake on 14 August originated on the Southern Peninsula Fault (also known as the Enriquillo - Plantain Garden Fault). LMI CARIBACT immediately launched field studies to determine and understand the origin of the earthquake and monitor its evolution, with an initial dispatch of seismometers and GPS stations to the epicentral zone. The data collected will also help understand the evolution of the current sequence of aftershocks. Studies will continue for several weeks, clarifying the level of seismic threat in this region and its evolution over time, and informing decision-makers on preventive seismic measures to be implemented to secure property and populations.

The initial scientific data obtained so far indicates that this was a shallow earthquake, probably located in the top 10 km of the Earth's crust with a mechanism combining north-south shortening and east-west strike-slip faulting, similar to that of 2010. The main seismic shock continues to be followed by aftershocks, some of which have reached magnitudes that may unfortunately cause further damage. The seismic sequence can be followed in real time at https://ayiti.unice.fr/ayiti-seismes/ thanks to Ayiti-Seismes citizen seismological stations.

Developed as part of the S2RHAI project (https://ayiti.unice.fr/sismo-ayiti/), the Ayiti-Séismes citizen seismological network is funded by the "Natural Risks” programme of the CNRS and the IRD, with contributions from the Faculty of Sciences of the State University of Haiti, the Haiti Bureau of Mines and Energy, the University and Observatory of Côte d’Azur, the Euro-Mediterranean Seismological Centre, the École normale supérieure and the Interreg Caraïbes PREST project.

LMI contacts: Eric Calais (eric.calais@ens.fr) and Dominique Boisson (dmboisson@yahoo.com)