Rapid Geodetic Shortening Across the Eastern Cordillera of NW Argentina Observed by the Puna-Andes GPS Array


McFarland, Phillip K.
Bennett, Richard A.
Alvarado, Patricia
and DeCelles, Peter G.

We present crustal velocities for 29 continuously recording GPS stations from the southern central Andes across the Puna, Eastern Cordillera, and Santa Barbara system for the period between the 27 February 2010 Maule and 1 April 2014 Iquique earthquakes in a South American frame. The velocity field exhibits a systematic decrease in magnitude from ~35 mm/yr near the trench to -19 × 10-9 yr-1, equivalent to clockwise rigid block rotation of the back arc at a rate of 1.1°/Myr.

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Figure 2. (a) Locations (stars), magnitudes, and times of earthquakes mentioned in text from the global centroid moment tensor (GCMT) catalog. (b) Map showing the contours and nodes (thin blue lines) used in subduction interface finite dislocation model prescribed from the SLAB 1.0 geometry with observed (black), model-predicted velocities (blue), and NZ-SA convergence vector (black with blue head) calculated at 24°S using the preferred Euler pole from Kendrick et al. (2003). Model-predicted velocities are from the subduction interface only component of model with all of NZ-SA convergence accommodated at the subduction interface (α = 1) as discussed in the text. (b) Map showing the location of the Peru-Chile trench and the RMS misfit of the subduction interface-only model-predicted velocities shown in Figure 1b to the observed horizontal velocities at each station shown in Figure 1b.

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Journal of Geophysical Research: Solid Earth, 122. https://doi.org/10.1002/2017JB014739