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High SO2 Levels Force Road Closure at Hawaii Volcanoes National Park


Scientist Jeff Sutton of the USGS Hawaiian Volcano Observatory gathers a gas sample at Kilauea’s summit. NPS photo by Tamar Elias

Unusually high, and potentially toxic, levels of sulfur dioxide have prompted the closure of a popular drive at Hawaii Volcanoes National Park.

While the gas is always present at the summit of Kilauea in an area adjacent to Halema‘uma‘u crater, trade winds normally disperse the gas, according to park officials.

But during the past month levels as high as 10 ppm have occurred in a narrow band south/southwest of Halema‘uma‘u. Studies indicate that 10 to 15 ppm concentrations of sulfur dioxide is a threshold of toxicity for prolonged human exposure. Exposure to sulfur dioxide can aggravate pre-existing heart and breathing problems such as asthma, park officials say.

In response to the elevated SO2 levels, Superintendent Cindy Orlando has issued the following orders:

* Crater Rim Drive between Jaggar Museum south/southeast to Chain of Craters Road is closed to all visitor activity, including driving, hiking, and bicycling until further notice due to high SO2 levels.

* Crater Rim Trail from Jaggar Museum parking lot south/southeast to Chain of Craters Road is closed.

* All trails leading to Halema`uma`u crater are closed including those from Byron Ledge, 'Iliahi (Sandalwood) Trail, and Ka'u Desert Trail.

* The park has postponed all work projects in the affected area.

The closures, signed and marked by traffic cones, will remain in effect until SO2 levels return to normal.


Here is an excerpt of the observation report I sent to Jim Kauahikaua last summer about the observations I made concerning gases in the halema'uma'u area:
"I’m back in France after two weeks spent on the Big Island. As lava was no longer flowing either on Pulama Pali or on the coastal flat, I could not perform any work on its cooling process as I had planned. Anyway, I made some good observations along the South-West Rift and the South flank of Kilauea which is currently seismically active.
I also made some temperature measurements and collected 2 gas samples along the rim of Halema’uma’u on July 13th. Temperatures were ranging between 71°C (160°F) on the northern rim and 82° C (190°F) on the southern rim at a depth of 50 centimetres.
The fumaroles mainly included water vapour (more than 80%) as well as some lesser amounts of CO2 and sulphur dioxide.
As far as the July 21st eruption is concerned, I flew over the active zone on July 24th. My observations confirm the update issued by the Observatory on that same day. I’m sending you a few photos I took of Pu’u O’o and the lava flows."

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