Fig. 1.

Surface displacement field for all SSEs recorded in northern Costa Rica since 2007, compared with the average inter-SSE surface velocity field during the same period. Error ellipses are omitted for clarity but are roughly the size of the arrowheads: The mean displacement uncertainty is 0.9 mm and 1.2 mm for the north and east components, respectively, and 0.5 mm/y for both components of velocity (1 SE). Uncertainty estimation procedures are described in ref. 9.