GNSS Constraints to Active Tectonic Deformations of the South American Continental Margin in Ecuador

GNSS observations constitute the main tool to reveal Earth's crustal deformations in order to improve the identification of geological hazards. The Ecuadorian Andes were formed by Nazca Plate subduction below the Pacific margin of the South American Plate. Active tectonic-related deformation continues to present, and it is constrained by 135 GPS stations of the RENAGE and REGME deployed by the IGM in Ecuador (1995.4-2011.0). They show a regional ENE displacement, increasing towards the N, of the deformed North Andean Sliver in respect to the South American Plate and Inca Sliver relatively stable areas. The heterogeneous displacements towards the NNE of the North Andean Sliver are interpreted as consequences of the coupling of the Carnegie Ridge in the subduction zone. The Dolores-Guayaquil megashear constitutes its southeastern boundary and includes the dextral to normal transfer Pallatanga fault, that develops the Guayaquil Gulf. This fault extends northeastward along the central part of the Cordillera Real, in relay with the reverse dextral Cosanga-Chingual fault and finally followed by the reverse dextral Sub-Andean fault zone. While the Ecuadorian margin and Andes is affected by ENE-WSW shortening, the easternmost Manabi Basin located in between the Cordillera Costanera and the Cordillera Occidental of the Andes, underwent moderate ENE-WSW extension and constitutes an active fore-arc basin of the Nazca plate subduction. The integration of the GPS and seismic data evidences that highest rates of deformation and the highest tectonic hazards in Ecuador are linked: to the subduction zone located in the coastal area; to the Pallatanga transfer fault; and to the Eastern Andes Sub-Andean faults.

Automated summary

GNSS observations are crucial in revealing crustal deformations, with the Ecuadorian Andes experiencing active tectonic-related deformation, including regional displacements formed by the interaction between the South American and Nazca plates. Integration of GPS and seismic data highlights that the highest rates of deformation and tectonic hazards in Ecuador are linked to the subduction zone in the coastal area, the Pallatanga transfer fault, and the Eastern Andes Sub-Andean faults.