The second project expedition to continue with the Ocean Bottom Seismic (OBS) experiment started in Tromsø on the 19th of August 2020. This part of the experiment consists in collecting the seismometers that have been recording seismic signals since last summer around the Vestnesa Ridge (check previous posts), and placing new seismometers closer to the northern termination of the Knipovich mid-ocean ridge axis (check the map below). We are working closely with our colleagues from the Alfred Wegener Institute (AWI) in Germany. They bring the expertise on seismology as well as needed instrumentation.
The west-Svalbard continental margin is very close to the active mid-ocean ridge and it is thus a natural laboratory to study the impact of regional tectonic processes on shallow Earth processes such as the release of methane to the ocean.
The continental margins are classified as tectonically active (if one plate is colliding against another plate) or inactive (if the continental plate is far away from the middle of the oceans (mid-ocean ridges) where new rocks are being produced constantly). But what happens if a continental margin is not so far away from the mid-ocean ridges? This is what we are investigating. We are searching for small earthquakes along a margin that is supposed to be inactive (the west-Svalbard margin). The presence of earthquakes that originate at faults that are away from the mid-ocean ridge will indicate that the movement of oceanic plates at the mid-ocean ridges spreads to fractures and broken parts of the continental plate along the so called passive continental margins. Processes such as the release of methane to the oceans from these margins may be thus affected by tectonic movement from the oceanic ridges.
We have been transiting to the Fram Strait for about 48 hours already. Before starting with the OBS experiment we plan to collect seismic lines that are needed to complete a proposal for the International Ocean Discovery Program (IODP).
But not all is about pursuing scientific objectives. We are currently towing a small passenger boat that called for help because they got a rope (garbage floating in the ocean) entangled in their propeller. Our captain rescued them and will tow them until the coast guard takes over or until leaving them in a safe place. We needed to postponed the first surveys and adjust the schedule. Most likely we will need to reduce the amount of data we collect this time but we will take with us the good feeling of solidarity.
R/V Helmer Hanssen tows a small passenger ship in trouble to a safe place
Text: Andreia Plaza-Faverola
Figures: Przemek Domel, Sunil Vadakkepuliyambatta and Andreia Plaza-Faverola