WP4 in ARCEx has conducted two field campaigns in Svea this spring under the leadership of Prof. Tor Arne Johansen at University of Bergen. ARCEx PhD student Ronny Tømmerbakke, who was out in the field, has sent us pictures and a short report from their activities in Svea.
For our study of flexural wave on a thin elastic plate we wanted to gather seismic data from a profile going from onshore over a shallow water transition zone to deeper water depths. The Kjellstrømdalen, Braganzavågen and Sveabukta area outside of Svea is ideally suited for this purpose.
After several years of limited sea ice around Svea the ice formed nicely this year and by mid-May Sysselmannen accepted our proposal for acquisition of seismic on and below the sea ice. Even though the ice was 50-60 cm thick, this late in the season it soon became a scramble to finish before the sun melted enough of the ice. A team of 8 people with assistance from UNIS logistics deployed 4.6 km of geophone strings on land based sea ice to water depths of over 50m, 60 hydrophones below the ice and 32 nodes on the seafloor below the ice. The deployed line was well inspected by a young male polar bear before shooting with both detonating cord and air guns.
The equipment was gathered and removed off the ice just in time before ice conditions started turning unfavorably. A team of 2 from Akvaplan-niva acted as seal observers monitoring the impact the seismic activity had on the seal behavior.
With the successful recording of data we now have a good dataset over the area of interest for further investigation into the behavior of flexural waves in sea ice.
Text and photos: Ronny Tømmerbakke.
WP4 field campaigns in Svea in 2017:
Location: Outer part of Kjellstrømdalen, Braganzavågen and inner part of van Mijenfjorden
Purpose: Based on the experiences fra the 2016 campaign, make a large scale seismic survey starting at land and transecting into very shallow ice covered water using various configurations of seismic set ups. The campaign was very successfull, a second phase of the experiement was initiated to take place late spring.
Collaborating partners: UiB, Eni
Duration: 16 days
Location: Inner part of van Mijenfjorden, Kapp Amsterdam
Purpose: (1) To monitor effects of seismic surveying on nearby colonies of ringed seals together with PhD student Ana Sofia Aniceto from WP3. (2) To extend experiments from earlier 2017 into deeper water. The campaign was very successful and has provided a unique data base for the ongoing WP4-activities related to seismic within and close to ice-covered surfaces.
Collaborating partners: UiB, Eni, Akvaplan-niva, IMR
Duration: 12 days