At about 3:30 am this morning, the Jason team began preparing Jason for its last dive of our expedition. At almost 4 am, the ships crew and the Jason winch operator and the rest of the Jason team lifted the ROV from the deck and lowered it into the water. After all systems are shown to be working then they added the 34 football floats and the transponder onto the cable. For this geology dive all of the chemical sampling equipment has been removed from Jason and extra milk crates with dividers have been added to Jason’s basket to hold the planned rock samples.
|New 2015 lava draping over older lavas on the NE rim of Axial.|
We see some cool pillow lavas from the 2015 eruption flowing down over the jumble of rocks and boulders at the base of the caldera wall. We collect another rock sample and Jason begins to rise up the side of the caldera about 65 meters high. Some of the caldera wall is a sheer rock face and we can see features like lava tubes and pillows that have been cut in half as if by a giant knife. This reminds me so much of road cuts along the Hawaii National Park Chain of Craters Road, but here we are a mile underwater.
|Collecting 2015 lava sample.|
After several hours of zig zagging across the graben while driving Jason northward and looking at the fractures the Jason team shift changes. Everyone takes turns eating breakfast and returning to the control van. At about 8:15 am we see some 2015 lava in the crack of a fissure. This is where a dike, or magma filled crack, reached the surface and lava squirted out. Much of the magma stayed underground in this part of the rift zone. We see fissures, but not much fresh lava.
|Control van view of lava pillar to be collected (center of large screen).|
At times during the dive, as we sit in the control van, it feels like one of those virtual experience rides, where you sit in a simulator and they show you flying in a space craft. The R/V Revelle provides some dips and rolls that match with Jason’s video movements and you feel like you are in a submersible flying (although slowly) through the water. As we move into the area where more lava erupted on Axial’s North Rift Zone, we see larger areas that are covered by thin ropy lava. There are really interesting sites that have the new lava flowing under, around and on top of the sediments that were here before the eruption. We saw sea pickles all over the lava flow. They are not supposed to be here and never were before. Now they are everywhere. They belong in more tropical waters, so it is worrisome to see them here, and are another piece of evidence of changing ocean conditions.
|Pillar collected in photo above right.|
We saw a number of cool lava pillars and areas of lava-sediment interactions. We ultimately collected 14 rock samples from the 2015 lava flows, and it's time to head back to the surface. We all must be getting hungry, as a discussion of where to get the best pizza in port ensued.
Back on deck at noon.