Along-strike segmentation in the northern Caribbean plate boundary zone (Hispaniola sector): tectonic implications
IPGP - Îlot Cuvier
Séminaires Géosciences Marines
Álvaro Rodríguez Zurrunero
Universidad Complutense de Madrid
The North American plate converges with the Caribbean plate at a rate of 20.0 ± 0.4 mm/yr. towards 254 ± 1º. Convergence is highly oblique to the plate boundary (10-20º), resulting in along-strike segmentation, strain partitioning and microplate tectonics. Series of large to great shallow earthquakes occurred in the northern Hispaniola margin in last two centuries. These earthquakes have been attributed to the underthrusting/collision of the relatively thick continental crust of the Carbonate Bahamas Banks beneath/with the Caribbean plate and to the left-lateral strike-slip motion along the Septentrional-Oriente fault zone.Seismic activity along the margin included the M8.0 historical event of 1842, four M>7.0 earthquakes between 1943-1953, including an Ms 8.1 tsunamigenic event in 1946, and an Mw 6.4 event in 2003. From 2005 to 2014 significant efforts were carried out to elucidate the crustal structure of the northern Hispaniola margin. An international collaborative research, leaded by the Universidad Complutense of Madrid, the Sorbonne Université, the Institut Français du Pétrole-Energie Nouvelles and the U.S. Geological Survey, carried out five geophysical cruises exploring the 500 km-long northern Hispaniola margin, from their western end in the Windward Passage to the eastern end in the Mona Passage. Cruises collected systematic high-resolution swath bathymetry, and multichannel seismic reflection data. We show results based on the combined interpretation of the new and old reprocessed data, GPS and seismicity of the shallow and deep structure of the northern Hispaniola margin. This margin can be divided into three main morphotectonic provinces: The Bahama Banks, the Hispaniola Trench and the Insular Margin. We study how these three provinces show the east-to-west transition from the highly oblique subduction in the Puerto Rico trench, to the oblique collision in the northeastern Hispaniola, to the oblique underthrusting in the north-northwestern Hispaniola and to strike-slip southern Cuba. Some of these faults seems to be deep-rooted structures that could be involved in the earthquake nucleation. These results and further interpretation of active deformational features will provide valuable information for the earthquake and tsunami assessment in the northern Hispaniola.