Extended Data Figure 4: Pre-seismic GPS displacement time series and maps.
From: Gradual unlocking of plate boundary controlled initiation of the 2014 Iquique earthquake
a, Map showing stations used for common-mode filtering (black triangles) and those to which the correction signal is applied (green triangles). b, East and north displacement time series of the detrended, common-mode filtered data are plotted with blue crosses. The green lines are the cumulative GPS displacements predicted by the forward modelling of elastic displacements for events in the seismic foreshock catalogue. Black vertical dashed lines indicate the onsets of the two clusters of 2014. The red dashed line shows the zero positions of the GPS after detrending. A significant departure of the data from this zero position is an indication of transient motion at that station. c, The two panels show the GPS data displacements (blue) and the forward modelled GPS displacements of the seismically related slip (red) during the periods shown above each panel. Both the data and the predictions have been smoothed with a nine-day moving-average filter. Error ellipses are shown for the data displacements. The black dashed line is the trench and the solid black lines are the coastline and political borders. Events from the foreshock catalogue for days within the specified periods (also considering length of smoothing window) are plotted in dark grey. For the first 2014 cluster (left panel), GPS stations of interest in the south move towards a common source. For the second 2014 cluster (right panel), GPS vectors point towards the eventual Mw 8.1 rupture zone.
