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On the interaction of the North Andes plate with the Caribbean and South American plates in northwestern South America from GPS geodesy and seismic data
AuthorPerez, Omar J.
Wesnousky, Steven G.
de la Rosa, Roberto
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We examine the hypocentral distribution of seismicity and a series of geodetic velocity vectors obtained from Global Positioning System observations between 1994 and 2015 both offshore and mainland northwestern South America (66 degrees W-77 degrees W 8 degrees N-14 degrees N). Our analysis, that includes a kinematic block modelling, shows that east of the Caribbean-South American-North Andes plates triple junction at similar to 68 degrees W 10.7 degrees N, right-lateral easterly oriented shear motion (similar to 19.6 +/- 2.0 mm yr(-1)) between the Caribbean and South America plates is split along two easterly striking, right-lateral strike-slip subparallel fault zones: the San Sebastian fault that runs off-shore theVenezuelan coast and slips about 17.0 +/- 0.5mm yr(-1) and the La Victoria fault, located on-shore to the south, which is accumulating strain equivalent to 2.6 +/- 0.4 mm yr(-1). West of the triple junction, relative right-lateral motion between the Caribbean and South American plates is mostly divided between the Morrocoy and Bocono fault systems that strike northwest and southwest from the triple junction, respectively, and bound the intervening North Andes plate that shows an easterly oriented geodetic slip of 15.0 +/- 1.0 mm yr(-1) relative to the South American plate. Slip on the Morrocoy fault is right-lateral and transtensional. Motion across the Bocono fault is also right-lateral but instead transpressional, divided between similar to 9 and 11 mm yr(-1) of right-slip on the Bocono fault and 2-5 mm yr(-1) of convergence across adjacent and subparallel thrust faults. Farther west of the triple junction, similar to 800 km away in northern Colombia, the Caribbean plate subducts to the southeast beneath the North Andes plate at a geodetically estimated rate of similar to 5-7 mm yr(-1).
|Journal Title||Geophysical Journal International|
|Rights||Creative Commons Attribution 4.0 International|
|Rights Holder||The Authors|