Seismological studies on ultraslow-spreading mid-ocean ridges are not numerous due to the fact that the most prominent members of these ridges are located in polar regions. Investigations on Gakkel Ridge in the ice-covered Arctic Ocean and Lena Trough located in the Fram Strait between Greenland and Spitsbergen require special logistics and techniques. Above the latitude of 80°N ice floes endanger the deployment and recovery of ocean-bottom seismometers even during Arctic summer. DFG funded Emmy Noether group 'Mid-Ocean Volcanoes and Earthquakes' located at Alfred-Wegener Institute for Polar and Marine Research is carrying out seismological studies on arctic mid-ocean ridges and developed adequate techniques to record local seismicity in ice-covered oceans. We are using small-aperture seismic arrays equipped with Guralp broadband sensors which are deployed on drifting ice floes by helicopters operating from icebreakers such as RV Polarstern or RV Oden. Due to limited transport capacity and difficult weather conditions the station's weight and the ability to install them fast are important factors. The sensor needs to be isolated well against the strong solar radiation during the Arctic summer. An array consists of three to four single stations installed on one ice floe with a minimal diameter of one kilometer. During a time span of up to two weeks the stations are drifting several tens of kilometers according to local swell and wind direction and speed. The broadband sensors record a wide variety of signals, for which we identified different sources. Those can be colliding ice floes, helicopters or ice breaking ships, seismic blasts from the ship during seismic profiling, earthquakes within local, regional or even teleseismic distances and sometimes even curious wildlife.
AWI Organizations > Geosciences > Junior Research Group: MOVE
Helmholtz Research Programs > PACES I (2009-2013) > TOPIC 3: Lessons from the Past > WP 3.2: Tectonic, Climate and Biosphere Development from Greenhouse to Icehouse