Text: Andreia Plaza-Faverola, leader. SEAMSTRESS project.
The second expedition to continue with the Ocean Bottom Seismic (OBS) experiment for the SEAMSTRESS project, started in Tromsø on the 19th of August 2020. This part of the experiment aims at collecting the seismometers that have been recording seismic signals since last summer around the Vestnesa Ridge. We will also be 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 continental margins are classified as tectonically active if one plate is colliding against another plate. They are classified as inactive if the continental plate is far away from the middle of the oceans (mid-ocean ridges) where new rocks are constantly produced. 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 supposedly inactive margin (the west-Svalbard margin). The presence of earthquakes originated at faults that are away from the mid-ocean ridge would 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 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 we can leave them in a safe place. We needed to postpone 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 a good feeling of solidarity.