During the 2009/2010 field season a vibroseismic source was used on a shelf ice for the very first time. In contrast to an explosive source, which produces a short broadband pulse as a source signal, a seismic vibrator produces a longer source signal of defined frequency. The field trip took place in January/Feburary with an international team from Bremerhaven, Bergen, Swansea, Innsbruck and Munich.

The vibroseismic measurements were carried out on the Ekströmisen shelf ice, Droning Maud Land, Antarctica next to the german research station Neumayer III. The Ekströmisen is about 100 - 200 m thick with a similar thickness of water column underneath. For further information and first results, please see the corresponding EGU poster.

Underneath 100 m of ice hydrophones are installed at PALAOA.  The Vibroseismic source was compared to the explosives, shots in 10 m deep boreholes, drilled with the air-pressure drill. Hence it could be figured out in which distance the signal could still be detcted.

It was rather difficult to find this limit for the explosives because of other noise. The vibroseismic signal could be detectd up to 7000 m.

A line of 19 km was shot with explosives as well as the Vibroseis from PALAOA towards Neumayer III.

The Snowstream was laid out in a loop and moved half the geophone distance, resulting in a trace spacing of 6.25 m.

• Vibroseis has lower frequencies than explosives
• Vibroseis needs convolution with initial wavlet to see reflections
• Work with Vibroseis is much faster as no boreholes need to be drilled
• Internal layers, water ice, water rock interface can be seen for both sources