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Abstract A devastating magnitude 7.2 earthquake struck Southern Haiti on 14 August 2021. The earthquake caused severe damage and over 2000 casualties. Resolving the earthquake rupture process can provide critical insights into hazard mitigation. Here we use integrated seismological analyses to obtain the rupture history of the 2021 earthquake. We find the earthquake first broke a blind thrust fault and then jumped to a disconnected strike‐slip fault. Neither of the fault configurations aligns with the left‐lateral tectonic boundary between the Caribbean and North American plates. The complex multi‐fault rupture may result from the oblique plate convergence in the region, so that the initial thrust rupture is due to the boundary‐normal compression and the following strike‐slip faulting originates from the Gonâve microplate block movement, orienting SW‐NE direction. The complex rupture development of the earthquake suggests that the regional deformation is accommodated by a network of segmented faults with diverse faulting conditions.
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This content will become publicly available on September 10, 2026
Paleoseismic evidence of directivity for the 1976 Mw 7.5 Motagua earthquake, Guatemala
Abstract On 4 February 1976, a Mw 7.5 earthquake along the Motagua fault, Guatemala, ruptured ~230 km of the North American and Caribbean plate boundary. Today, the plate boundary remains poorly monitored, and the 1976 earthquake is still not fully understood. Here, we present seismic reflection profiles and radiometrically dated sediment core data from six lakes around the Motagua fault, together with reports of destruction and a quasi-dynamic rupture model, which show that the 1976 earthquake experienced strong directivity that impacted the distribution of shaking. The earthquake left behind a detailed record of event deposits (EDs) in five of the six study lakes. Thicker EDs are present in Lake Atitlán, near the terminus of the earthquake rupture, whereas thinner EDs were found in lakes off-axis of the rupture direction. We argue that EDs can be utilized to constrain asymmetrical distribution of shaking during earthquakes and that paleoseismic studies should consider directivity as a factor controlling the thickness of EDs.
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- PAR ID:
- 10650357
- Publisher / Repository:
- Geological Society of America
- Date Published:
- Journal Name:
- Geology
- Volume:
- 53
- Issue:
- 11
- ISSN:
- 0091-7613
- Page Range / eLocation ID:
- 971 to 976
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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