Geophone 8: gone, but not forgotten.
There are many approaches to designing a geophone network on a glacier, but one of the most important controls on data quality is coupling: the better the contact between the ice and the geophone, the higher the quality of the seismograms recorded. However, good coupling usually comes at a price- in this case, the ultimate price.
Because geophones only work when they are kept upright, the best way to deploy them on Store Glacier (where during summer, the surface can melt very rapidly) is to drill a vertical, cylindrical hole to 6+ m depth and lower the geophone in. The ice freezes directly onto the geophone and the coupling is fantastic. Alas, the Greenlandic weather is not kind to this setup – rapid temperature fluctuations during autumn and spring can literally rip the cable from the geophone housing. Of the 12 surface geophones deployed last year, not a single one survived the transition from winter to summer unscathed.
Not to be deterred, we deployed another 4 geophones this summer. While not as
expansive as last year’s passive seismic network, we are confident we’ll still record many
interesting sounds from the nearby moulin.