Archive of September 26th, 2007

Teacher at Sea log for September 26, 2007

Traditionally sailors have been known for their arts and crafts. A long time ago, teeth and bones from whales and walruses were carved into scrimshaw. Shells and exotic woods were worked into inlaid and polished boxes. We are out to sea for much less time, but the crew of our ship serves for three months at a stretch. How do they keep it interesting?

• We have fabulous food and an amazing cooking staff.
• Ringold spends his free time making beautiful art.
• Sometimes it is a nice change to have a barbeque on the upper deck.
• Scientists love their work and their books.
• Some of us have brought along recreational reading.
• Many enjoy taking photographs.
• Re-loading MP3 players with something new to listen to.
• We play card games.
• We have e-mail to keep in touch with home.
• We play computer games.
• Spotting birds, dolphins and fish over the bow is always fun.
• Learning the stars and constellations makes a great nighttime activity.
• We watch DVD's nearly every night.
• We keep up with daily tasks such as exercise and laundry.
• And then there are Lawson's pranks and Claude's magic tricks.

Science Update by Garrett Apuzen-Ito

Today our chief scientist, Mike Garcia, presented his recent work on "rejuvenated" volcanism in the Hawaiian Islands. This stimulated a discussion of the evolution of Hawaiian volcanism as it pertains to our expedition.

Most of the mass of the main Hawaiian Islands is made of tholeiitic basalt, which formed during the "shield" volcano stage. Mauna Loa and Mauna Kea are among the largest volcanic shields in the whole Hawaiian chain; Kilauea is the youngest and, currently, most active shield volcano. The diagram below shows age of volcanism, plotted versus distance away from Kilauea. As you can see, the shield stages (red) occur first on all of the islands, and the ages of the shields increase to the northwest up the island chain. The shield stage is followed by a small-volume, "post-shield" phase (blue), which on Mauna Kea is represented by the small cones that that pepper Mauna Kea’s summit. Volcanism stops after about 0.5-1 Myr (see graph).

Then, on some of the older islands starting with West Maui, volcanism becomes rejuvenated (yellow bars) after 0.6-1.4 Myr of no volcanic activity. This "rejuvenated" or "secondary" form of volcanism is also relatively small in volume but can be explosive and generates many of Hawaii’s spectacular land forms such as those shown in the air-photo over Honolulu. Other examples include Rabbit Island, Koko Crater, and Hanauma Bay on Oahu, and Kilauea Point and Kilo Hana cone on Kaua'i.

Presented by the School of Ocean and Earth Science and Technology at the University of Hawaii, with financial support from the National Science Foundation.