Moulins Detected as Ambient Noise Sources at the Kaskawulsh Glacier

The hydrology of glaciers plays an important role in ice sheet and glacier dynamics. To evaluate the effect of meltwater on basal sliding, it is important to monitor the hydrological drainage process in detail. Since the meltwater drainage processes of glaciers generate seismic signals, passive seismic source analysis has potential for this purpose. The confluence of the north and central arms of the Kaskawulsh Glacier in Yukon, Canada, is an especially attractive place to study such phenomena not only because of the confluence but also because a nearby ice-dammed lake fills and drains rapidly every summer. We analyze geophone data from nine stations at the Kaskawulsh Glacier during the summer of 2014 to locate ambient noise sources. We determine ambient noise source locations using the cross-correlated seismogram. We apply several seismological techniques such as the ordinary source location method, the back-projection method, and the double-difference relocation technique. Stronger seismic radiation is observed in the daytime possibly related to melting of the glacier. Most of the ambient noise sequences are located in two clusters, with each cluster located in the vicinity of a moulin identified at the surface. We interpret this ambient noise as being produced by meltwater drainage. We also see diurnal migration of the source in horizontal downstream direction while the vertical source location is difficult to determine. We interpret this migration as a diurnal change of the water level in a moulin that has a profile in the downstream direction.