FeMO3 Dive Cruise 2008
Report Day 11 -- Thursday 2 October 2008 -- Halfway Scientists Exchange
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FeMO3 Dive Cruise 2008 |
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After my shift in the van, I look at the stars and find Cassiopeia and the Little Dipper. This far south (19 degrees north of the Equator) at this time of night the bucket of the Big Dipper is below the horizon. Or maybe it’s behind the summit of Mauna Loa; it’s hard to tell because of the haze on the horizon. The Jason techs and ship’s crew are preparing to recover Medea and Jason. They will then do another CTD cast over the summit of Lo’ihi. And finally, the ship will steam for Kona in the lee of the Big Island.
I wake shortly after the ship gets underway. The Thompson is riding gently in a following sea, but the fittings in the cabin are vibrating and buzzing in an unfamiliar way because of the engines and propellers. I can’t tell what time it is. The stateroom is on the waterline so there are no portholes to let light in – and I failed to bring a watch. Something’s happening so I decide to get up. I get dressed and go up to the main lab to find it is only 5:30 in the morning. Despite the time, several scientists are still working on samples brought up on deck 5 hours earlier.
About 6am the sky is lightening and we can begin to see the summit of Mauna Loa looming above the haze. Mauna Loa is so large and smooth and high that its effect is disconcerting. When sailing toward it, Mauna Loa rises above a screen of ocean haze like another line of clouds. When you finally realize the line of dark clouds is a mountain of basalt it suddenly seems much closer than it should. At the time I asked myself “How did it get that close without me noticing it?”
At the base of Mauna Loa where you would expect to see a line of breakers is a darker haze. The haze is created by great clouds of steam boiling into the sky where lava pours from Kilauea into the ocean. The steam plume carries with it ions from the salt water and volcanic gasses from the lava. The plume is reinforced by volcanic gasses from the summit crater of Kilauea 4000 feet above. (Years ago I looked into that crater and it seemed cold and dead, now it is a burning lake filled with sloshing lava.) The seawater contributes chlorine ions and the volcano contributes sulfur – together they form an acidic cloud that prickles your skin and gives you a sore throat. The plume of steam and volcanic gasses is called Vog, for volcanic fog. Vog causes enough health problems that the state of Hawaii posts Vog alerts like LA posts smog alerts.
From our station over Lo’ihi we have been able to see the Vog plume as the trade winds blow it towards South Point on the Big Island. But this particular morning we are rounding South Point and crossing the plume. Several of us are on deck to admire the sunrise and we can see the plume rise as it drifts over the long low point. We can smell the stink of sulfur and feel the effects in our throats. After about 30 minutes on deck my throat is raw.
Shawn Doan onboard the R/V Thomas G. Thompson
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