The new Sentinel-1A radar satellite has already shown that it can be used to generate 3D models of Earth’s surface and will be able to closely monitor terrain deformation. As the first in a fleet of satellite missions for Europe’s Copernicus environmental monitoring programme, Sentinel-1A was launched on 3 April, 2014. This summer’s Napa Valley earthquake was an opportunity for Sentinel to produce an interferogram that accurately depicts post-seismic deformation.