Fig. 11

N-S ground displacements at Sierra Negra volcano: September 2017 – June 2018 time interval. (a) Comparison between the retrieved N-S displacement component from \(\phi\)u (red dots) and GNSS (blue triangles) time-series. ξ indicates the related RMSE. (b) Mean N-S displacement velocity map calculated from \(\phi\)u. The GV01 GNSS station represents the reference point. Coordinates are expressed in the UTM reference system (UTM zone: 15 S).