Abstract Subglacial processes are key to glacier dynamics but remain poorly constrained due to limited in situ observations. We use continuous seismic and Global Navigation Satellite System (GNSS) measurements to investigate summer basal conditions at Sermeq Kujalleq in Kangia (SKK; Jakobshavn Isbræ), Kalaallit Nunaat (Greenland). Seismic analysis (HVSR) captured changes in ice resonance, while GNSS monitored surface velocity variations. By late June, a low‐frequency resonance peak emerged and coincided with flow acceleration and vertical uplift, consistent with elevated simulated basal water pressure. HVSR data thus captured the onset of the melt season, revealing the transition from an ice‐bed state where limited meltwater maintains strong coupling, to a partially decoupled state driven by sustained meltwater. Rayleigh‐wave modeling indicated that the observed changes could be reproduced by a reduction in the rigidity of basal sediments. These findings highlight how glaciated areas surrounding ice streams, although slower flowing, can still exhibit fast‐changing dynamics.
Ginkel et al. (Fri,) studied this question.