FeMO2 Dive Cruise 2007
Report Day 07 -- Wednesday 17 October 2007 -- Scientists Swap
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FeMO2 Dive Cruise 2007 |
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Jason survives the Pit of Death (dive 310) and surfaces. The tether camera catches several mahi-mahi swimming around the tether. As the Kilo Moana turns for Kona, Kuhio hooks into a 20 lb. mahi-mahi and delivers it to Shawn, the chef, who makes delicious fish and chips for lunch. The mahi-mahi is firm and flakey with a light flavor and very lightly coated, not saturated with a thick coat of batter. Supreme!
This morning we leave station to sail to Kona on the southwest side of the big island to exchange scientists. The Kona coast is well sheltered from the trade wind swell and clouds - it is calmer, warmer and sunnier. During transit the clouds lift and we can see the shoreline better. The huge sloping mass of Mauna Loa tilts toward us. Near South Point we see cinder cones near the shoreline. Further north the black basalt gives way to trees and shrubs. Near Kona are black scars in the vegetation that highlights construction of housing developments and shopping centers. Two enormous cruise ships are laying offshore Kona. The Kilo Moana comes to rest a mile or so from shore, outside the cruise ships, and the small boat is made ready. Passengers climb aboard the small boat from the 01 deck well above the water and are lowered by crane to the surface. Alexis, Brad, Don and In Chieh go ashore in two trips and are replaced by Amanda, Dave, Katrina, Lisa and Roman. Once everyone is aboard, the Kilo Moana turns toward South Point for our return to Lo'ihi.
We return to take up station over Pele's Pit by 11 pm. The deep-sea elevator is loaded in preparation for decent to the center of Pele's Pit, to be followed by Jason. This will be dive 311.
Pele's Pit formed in 1996 when the old summit of Lo'ihi collapsed into the pit during a volcanic eruption. It probably formed as magma drained out from under the old summit causing it to collapse. A remnant of the old summit sticks up 400 m above the floor of the pit just to the north. The 1996 eruption was accompanied by the largest swarm of earthquakes ever measured in the Hawaiian Islands.
Lo'ihi was discovered in 1952 as the location of a swarm of small earthquakes that lead researchers to survey the ocean southeast of Mauna Loa. Dredging at the summit recovered fresh volcanic glass and basalt, confirming that this was an active volcano. By 1996 hydrothermal vents had been discovered with the Pisces submarine and these vents had become a regular sampling location called Pele's Vents. During the 1996 eruption the vents collapsed into Pele's Pit. Just after the eruption water temperatures of ~200 degrees Celsius were measured at new vent sites in the pit. These temperatures dropped quickly at first, and then more slowly. So far the highest temperature we have measured this year is 54 degrees Celsius. The highest temperatures are in Pele's Pit, but there are other vents issuing warm water. An interesting summary of research on Lo'ihi is given in "Geology, geochemistry, and earthquake history of Lo'ihi Seamount, Hawai'i's youngest volcano" by Garcia, Caplan-Auerbach, De Carlo, Kurz and Becker (Chemie der Erde, 2005).
Jason is put in the water shortly after midnight, finds the deep-sea elevator and begins work.
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