Rupture Scenarios for the 3 June 1770 Haiti Earthquake

The 2010 M 7.0 Haiti earthquake provided the impetus to reconsider historical earthquakes in Hispaniola (Bakun et al., 2012). That earthquake also shed new light on complex fault sys-tems along Haiti's southern peninsula (Douilly et al., 2013; Saint Fleur et al., 2015). Recently, the 2021 M 7.2 Nippes earthquake (Calais et al., 2022; Douilly et al., 2022), and a recent study reconsidering the 1860 sequence (Martin et al., 2022) further underscored the complexity of fault systems and large earthquake ruptures along the peninsula. Motivated by these studies and recent geological investigations (Prentice et al., 2010; Saint Fleur et al., 2020), we recon-sider the 3 June 1770 Haiti earthquake to explore the conventional assumption that it was the last major (M >= 7.5) earthquake along the Enriquillo-Plantain Garden fault (EPGF). Accounts provide compelling evidence for substantial liquefaction in the Cul-de-Sac plain, one or more likely landslide-driven tsunami in Gonaives Bay, and extensive landsliding that created at least three documented landslide dams. We consider three end-member rupture scenarios that are consistent with available constraints: two scenarios with M 7.7 and rupture lengths of 150-170 km, and one scenario with a similar to 90 km rupture and M 7.5. Absent future work to identify and date paleoevents along the southern peninsula, none of these scenarios can be ruled out. Our preferred rupture model extends from the Miragoane pull-apart to near la Selle mountain, with a rupture length of 127 km, M 7.6, and a high stress drop. Rupture could have been on the EPGF or on an oblique thrust fault associated with overthrusting of the Massif de la Selle. The results do support the conclusion that the 1770 earthquake was the last major earthquake in southern Haiti, with a magnitude upward of M 7.5 and significantly more severe shaking in southern Haiti than during the 2010 earthquake.