*3.1. Geodesy*

During and after the Krafla Fires, crustal movements have been monitored by levelling and GPS measurements and later by Interferometric Synthetic Aperture Radar (InSAR). Inflation continued until 1989, when a deflation started. In the beginning, the subsidence was about 7 cm/year but decreased exponentially with time and by 2008 it was practically over [23]. After that, crustal deformation (subsidence) has been attributed mainly to pressure draw-down in the geothermal reservoir. From recent InSAR and GPS measurements, it appears that the deflation of the Krafla caldera since 1989 has reverted to a minor inflation at a rate of 10–15 mm/year in 2018–2019 [24]. Whether this is due to magma transport or re-injection of fluids into the geothermal reservoir needs to be worked out.
