Seismics on a cold alpine saddle - limits and challenges
The Colle Gnifetti is a glacier plateau at about 4450 m altitude in the Monte Rosa, Swiss Alps. Due to the altitude and a mean annual air temperature of around -14°C hardly any melting occurs. Colle Gnifetti therefore resembles very well polar ice conditions and gives the opportunity to test and optimize geophysical methods for polar deployment close by with a comparable low logistic effort. Seismic as well as radar measurements were carried out in August 2008 next to the ice core KCI. So far it has not been very common to use seismics on a cold alpine glacier with such a large thickness fraction of the firn layer. The aim was to gain results about the ice properties and ice structures using these geophysical techniques. For the seismic data this proved to be difficult. Because of the comparably shallow character of the glacier in respect to the seismic wave length the ground roll as well as the refractions were overlaying the reflections. As it turned out it was already a challenge to be able to see the bed reflections, suggesting the need for a different shot-receiver geometry. Besides this, ringing of the geophones at the spurious frequency occurred, showing the upper limit for the recordable frequencies at 200 Hz.
AWI Organizations > Geosciences > Junior Research Group: LIMPICS
Helmholtz Research Programs > PACES I (2009-2013) > TOPIC 1: The Changing Arctic and Antarctic > WP 1.1: Role of Ice Sheets in the Earth System