Global Positioning System Constraints on Active Crustal Deformation in Central Panama

Abstract

Online Material: Figures of three‐component GPS displacements and residuals; table of derived velocities. The tectonic setting of central Panama has been controlled primarily by the collision of the Central American Arc with the South American continent, beginning in Miocene time (e.g., Coates et al. , 2004). Ongoing collision at a rate of about 25 mm/yr has been inferred using campaign‐style Global Positioning System (GPS) surveys from a sparse, long‐baseline network covering the collision zone (e.g., Trenkamp et al. , 2002; Fig. 1). The central portion of the Panama block (Figs. 1 and 2) is commonly described as a nondeforming microplate (e.g., Trenkamp et al. , 2002; Bird, 2003; Argus et al. , 2011). However, appreciable Pleistocene crustal deformation has been suggested in central Panama based on an analysis of the landscape and paleoseismological trenches (Rockwell et al. , 2010a), and is likely a consequence of ongoing collision diffusely absorbing a fraction of Cocos–Nazca–Caribbean–South America relative plate motion (Rockwell, Bennett et al. , 2010). Figure 1. The regional tectonic setting of Central America. Plate boundaries from Bird (2003) are shown with thick lines, superimposed on shaded topography and bathymetry. The political border of Panama is highlighted with a thin black line. Vectors show the approximate sense of motion of the various plates, including the Panama block, relative to a South America fixed‐velocity reference frame. Ongoing collision of the Panama block with the Northern Andes block continent results in appreciable deformation of central Panama and northwest South America. NPDB shows the location of the North Panama deformed belt, which separates the Caribbean plate from the Panama block. The small square in the Panama block shows the area of Figure 2, which encompasses the Rio Gatun, Limon, and Pedro Miguel faults, …