March 13, 2001 to June 2, 2001
Monterey to Hawaii and back
May 17, 2001: Leg 4; Day 9
Dave Clague writes: The last dive on Leg 4 of the Hawaii expedition is underway as I write this. After we recover the vehicle tonight, we will steam for Honolulu for arrival at 8 a.m. Friday. The dive today is a continuation of the heat flow transect begun yesterday that MBARI Post-doctoral Scientist Kelsey Jordahl described in yesterday's report. This part of the expedition was a resounding success with 57 dives around the Hawaiian Islands during legs 2, 3 and 4 that collected 1182 rock samples, 136 pushcores, 49 sediment scoop samples, 32 heat-flow measurements, 21 live animals (leg 4 only), and 38 animals frozen for DNA studies.
We had poor luck with the weather during legs 2 and 3, but conditions improved during leg 4 and we were able to complete the program we had planned. We never got to dive on Loihi Seamount, Papa'u Seamount, Hilo Ridge, or Hana Ridge offshore Haleakala due to poor weather conditions, but added work on the South Kona landslide, drowned reefs around Lanai and Kahoolawe, the Kahoolawe submarine rift zone, drowned reefs off Oahu, the Waianae landslide off the west coast of Oahu, and additional work on the west side of Kohala Volcano.
We collected rejuvenated stage lavas from cones offshore Oahu, Kauai, and Niihau, and from several vents in the deep channel between Kauai and Oahu. We sampled drowned coral reefs on Niihau, Oahu, Molokai, Lanai, Kahoolawe, and on the east and west sides of Kohala Volcano on Hawaii. The reefs we sampled contain a rich history of climate change over the past 5 million years, in addition to defining the subsidence history of the various islands. We also sampled the flanks of Niihau, Waianae, Molokai, Mauna Loa, and Kohala volcanoes. In each case, the flanks of the islands are composed mainly of volcaniclastic rocks. We examined the structure and eruptive products of a number of volcanic landforms including flat-topped volcanic cones, pointed cones, fissures that produced linear vent constructs, and several examples of submarine lava ponds. The samples and data will take several years to completely analyze, but we are all heading home feeling somewhat exhausted, but exhilarated about what we have learned.
I want to particularly recognize the cheerful support and hard work of the many MBARI staff and the non-MBARI scientists who joined us and made the expedition such a success. The non-MBARI scientists who participated on the expedition included summer intern Kristen Benchley (leg 2), Lizet Christiansen (leg 4), Brian Cousens (leg 4), Jackie Dixon (leg 4), Ken Hon (leg 4), Billy Moore (leg 3), Jim Moore (leg 3), Juli Morgan (leg 2), Jennifer Reynolds (legs 2 and 4), Ed Seidel (leg 4),and Jerry Winterer (leg 2). In addition, the entire ship crew under Captain Ian Young and Tiburon ROV team under Dale Graves performed extraordinary feats on a regular basis to keep us working under adverse conditions. They made it all look easy! Their effort and skill are the foundation that allows the scientists to execute their programs. Mahalo to all of them.