Hawaii Cruise
March 13, 2001 to June 2, 2001
Monterey to Hawaii and back

April 4, 2001: Leg 2; Day 4

Buzz Scott prepares Tiburon for a dive.

Kyra Schlining writes: We had planned to dive pretty deep off the southeast corner of Maui but were weathered out by winds whipping between Maui & Hawaii, so we had to make the long, bumpy transit back to the shelter of Mahukona, west of Hawaii (where we dove yesterday). Luckily the dive is going well so far. The crew took advantage of the transit time to do some maintenance on the ROV and around the ship. They were particularly concerned about a fraying cable on the ROV clump-weight system (used to help stabilize the ROV during recovery) (see Dale Graves and Dave French working on that in images).

On another note, I had a great b-day aboard the ship today. Doug made me a banana bread birthday cake that was delicious! We also had dolphins bow riding and saw whales (probably humpbacks) breaching. Very cool!

Jenny Paduan writes: April 5, 2001 01:30 (yes, I'm going to hit the rack soon)

Aloha from off the Kona Coast. Here are a few framegrabs from the April 4 dive on an ancient coral reef.

apr4_00_00_00_01.jpg (23408 bytes)The ship's haunches just after the ROV was launched. The water here is so clear and blue. We've seen very little marine snow, as well. It is no surprise that the bottom dwellers are quite sparse, since they depend on particles drifting down for their food.

apr4_00_59_52_13.jpg (68157 bytes)A basalt cobble we sampled with the manipulator arm.
It either weathered out of the eroded coral reef, visible behind the rock, or tumbled down from a flow above.

apr4_00_39_56_03.jpg (42448 bytes)A closeup of the flow meter on the new radium sampler mounted to the ROV. The sampler pumps seawater through a mesh to concentrate radium. Radium is a naturally occurring radioactive tracer, which is measured to give an indication of how long ago the seawater percolated through sediments. In normal seawater, radium is nearly undetectable by current techniques, but it picks up radium as it passes through the sediments.

apr4_01_14_15_17.jpg (44995 bytes)A shot of a computer screen in the control room showing the real time GIS (Geographical Information System) navigation program (developed at MBARI) we use to plot our location during a dive. The ROV's position is the blue icon. The positions are updated every few seconds and they appear on the high resolution map we made several years ago. We can also mark points along our path, such as where samples are collected or where we want to comment about the terrain, so we have a record of where these observations were made.

Lance Wardle stows the winch on the back deck.

Dave Clague writes: Today was a pretty strange day-frustrating at times and ending with a highly successful dive. We steamed overnight through the channel between Maui and Hawaii to a dive site on the east rift zone of Haleakala Volcano. This channel is notorious as a rough patch of the ocean and today was no exception. The ship was buffeted by headwinds to 50 kts and heavy seas. Even after leaving the channel, the winds only dropped off to 35 kts and we decided that we could not launch in such miserable conditions. We then steamed (much more comfortably, since the wind and seas were pushing us along) back to the drowned reefs off the west coast of Kohala Volcano. On arriving at the chosen site, we found that the surface currents were too strong, so we moved to a secondary site, where we finally were able to launch.

The dive was to the same 400 m reef we had dived on the previous day. This dive explored a deep embayment in the reef where we were able to see deeply into the reef. We were able to see the forereef beds of debris that slope down the outer face of the reef as well as the flat-lying reef itself. Having learned from previous dives what the corals look like in outcrop, we were able to collect many coral samples from various levels in the reef and also found a lava flow that had flowed over the reef, depositing many boulders on the outer slope and on top of the reef. At the end of the dive we discovered a set of large open cracks in the reef top that parallel the break-in-slope. At one point a channel of sediment ended at a large crack. These types of structures in mountain belts on land, with apparent dikes of sandstone in reef limestone, are known as Neptunian dikes.

The two crossings of the reef from this dive will be added to our observations from the previous dive here to construct a history of this reef and add to our understanding of the volcanoes that supplied the lava flows. At the end of the dive we collected two rock crusher samples from two small volcanic cones that are aligned with the cones we explored on our first dive in this area. The rock crusher is a wax-tipped coring device deployed on a wire over the stern of the ship that is designed to collect volcanic glass from the surfaces of lava flows. Both samples recovered altered lava fragments, some glass, and some fresh lava fragments. The clasts have different mineral contents than the samples from the deeper cones sampled earlier, suggesting that there are at least two eruptive fissures here. Slowly, the pieces of the puzzle come together.

Dale Graves examines the frayed clump-weight cable.

Dave French (one of three Dave's aboard now!) assists with the cable repairs.


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