|University of New Hampshire; Center for Coastal and Ocean Mapping/Joint Hydrographic Center|
July 28, 2021
Lat: 59.369° N, Long: 30.180° E
Winds: North-Northwest at 15 knots
The CCGS Louis S. ST-Laurent took a small break from transiting across the Atlantic Ocean yesterday. On July 27th at approximately 21:00 UTC we had arrived at the location of several underwater volcanoes discovered during the Galway 2015 transit. One of our main goals for the Galway 2016 cruise was to expand the multibeam coverage of the volcano area. We spent 13 hours at this site, hoping to discover new volcanoes and re-survey the existing data to determine any changes in volcano morphology since last year.
Before beginning the volcano survey operations we collected a new sound velocity profile and asked the captain to lower the speed of the CCGS Louis S. ST-Laurent from 15 to 9 knots; these steps allowed us to collect higher density and more accurate bathymetric data. We collected data on 5 lines, each approximately 24 nautical miles long, which ran parallel to last year’s collected data.
Figure 1. Galway volcano survey 2016 (green line) overlaid on 2015 transit data.
The final volcano survey ran for 135 nautical miles and encompassed an area of 270nm2 (950 km2). The cleaned multibeam data (which includes data from both 2016 and 2015) exhibits rough and varied seafloor morphology. Several ridge features run in a northeasterly direction through the area, rising an average of 250 meter above the seafloor. Volcano-like features can be identified by their cylindrical, relatively smooth shape and caldera (round opening at the top). The science team has identified more than 30 volcano-like features throughout the area at varying stages of development and at least 14 features with calderas, 4 of which were found in the 2015 data and. The tallest of these possible volcanoes is 280m high along the ridge.
Figure 2. Galway volcano-like features, note the cylindrical and relatively smooth shape and the caldera (round opening at the top).