FeMO2 Dive Cruise 2007
Report Day 04 -- Sunday 14 October 2007 -- Diving into Pele's Pit


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The summit of Loihi is 4,000 meters above the deep site at Ula Nui - Loihi is 2 miles high, yet its summit is still more than a mile below sea level. Loihi lies on the submerged trailing flank of Mauna Loa. Mauna Loa rises miles above sea level. Her sister mountain, Mauna Kea, rises a couple hundred feet higher, making Mauna Kea the highest peak in the Pacific. Mauna Kea is so high that it often has snow on its summit despite its location on the Tropic of Cancer. Mauna Kea means "White Mountain" in Hawaiian. From the deep ocean floor to the summit of Mauna Kea is more than 8,000 meters - a pile of volcanic basalt more than 5 miles high erupted from the seafloor. Loihi is inheriting this legacy. As the Pacific Plate moves over the Hawaiian hotspot Mauna Kea and Mauna Loa move further from the volcanic vents that build the islands of Hawaii.


The JASON elevator in Pele's Pit

After the transponder net is surveyed a deep sea "elevator" is sent to the bottom to aid in the deployment of experiments and the recovery of samples. Jason has a total payload of 750 lbs (about 350 kg) air weight. This includes all instruments, probes, samplers, slurps, rocks and the water contained in the sample boxes. The elevator was built to make it possible for Jason to stay on the seafloor longer for more tasks, without being limited by its maximum payload. It is a weighted platform with floats above and release mechanism and anchor weights below. Jason will recover scientific gear from the elevator, return to the elevator with samples that he secures to the platform. When the elevator platform is full, its weights will be dropped and the elevator will float to the surface. Jason can stay under water for more than 3 days. Without the elevator Jason would have to return to the surface to deliver samples and gather more equipment. For each deployment, the engineers need Jason on board for at least 12 hours for service between dives.


Chief Scientist Craig Moyer in the JASON van

Jason's dive began about 4 am in Pele's Pit. Pele is the Hawaiian volcano goddess and the images captured by Jason's cameras show the orange colored rocks and shimmering hot water that reveal the volcanic nature of Loihi. The pit is the summit caldera of Loihi. Loihi's summit reaches to within 960 meters of the oceans surface, while the bottom of the pit is 1350 meters depth. The topography in the pit is so rugged that 4 transponders have been used for the navigation network. Jason first locates the elevator and recovers the thermal gradient recorder and the electrochemistry probes. With the probes aboard Jason begins to search for the first of a dozen research sites that were established throughout the caldera during previous expeditions. Research sites and research projects that contribute to the FeMO have been established at Loihi for at least 7 years and since 2005 these diverse projects have been coordinated under the FeMO program.

Today's dives in Pele's pit are going extremely well when suddenly Jason hits the side of the pit causing a small underwater landslide. The monitors show falling rock and muddy water that raise large plumes of sediment that quickly block the cameras. A moment later a call comes from the bridge that the Kilo Moana has lost its ability to hold position over Jason and Medea. Jason is pulled up above the bottom until the ship can be repaired. Three hours later it is still not certain whether the ship can be prepared while Jason is in the water or Jason will have to be recovered.



Shawn Doan onboard the R/V Kilo Moana
20 October, 2007


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