Today we completed our first dredge of the new summit in Vailulu’u, Nafanua. This resulted in about 300lbs of rocks being collected from the ocean’s floor. After this first dredge however, the pinger, which is located 300m above the dredge on the cable, ran out of battery power on the way down for the second dredge spot. Since the cable had already been lowered over 3000m however, it was decided to continue with the dredge blind. The pinger, allows the ship’s sonar to detect how far the dredge is from the bottom (since the ship is moving, the cable is not straight down). During this second run, the dredge became stuck for a few hours on the bottom, but luckily the ocean eventually yielded the dredge and several pounds of rocks.

Ever since the first dredge came up, the science team has been working around the clock to try and catalogue the various rocks which were pulled up by the dredging runs. The rocks from the first dredge were quite newly formed, although this is evident from the geology, we also know from previous mappings of Vailulu’u that the rock is not only new in geological terms, but actually less than four years old. The second site however, was from outside of Vailulu’u, and had rocks that were both much older, and much harder.

The forces involved in dredging are quite impressive; in fact, the 1.5 inch thick steel frame which makes up the front of the dredge was put under so much stress it is almost completely round now. It was already bowing out from previous runs, but now the over 12 thousand pounds of force which we measured up at the ship, must have caught up to it, further degrading its shape and structural integrity.

Ryan Delaney onboard the R/V Kilo Moana.