Deformation observed at Fourpeaked covers both the Douglas and  Fourpeaked areas. InSAR measurements show broad inflation of this region between 2003–2010, with deformation mostly vertical. This deformation is modelled by a Mogi source of poorly constrained depth (5 – 10 km). Fixing the depth to that of local seismicity (7 km) yields an average rate of volume change of ~0.004 km³/year. Deformation is attributed to magmatic intrusion (possibly episodic), or isostatic rebound as the ice cap thins and recedes.