HILO, Hawai'i — Another small explosion jolted Halema'uma'u crater early yesterday morning, and high sulfur dioxide emissions detected in Hawaiian Ocean View Estates in Ka'u prompted a short-lived warning about air quality from Hawai'i County Civil Defense.

The warning was downgraded at 10 a.m. yesterday after the levels of the gas dropped.

Scientists with the U.S. Geological Survey's Hawaiian Volcano Observatory said a blast at the crater shortly before 4 a.m. deposited faintly pink ash across the Halema'uma'u overlook parking lot and along a section of Crater Rim Drive.

Scientists said the ash appeared to be rock dust, and that they found no volcanic glass fragments in the debris.

At 7:45 a.m. yesterday, civil defense officials advised residents of Hawaiian Ocean View Estates above Hawai'i Belt Road that sulfur dioxide levels there "may be high enough to cause severe reactions (for) those in the sensitive groups as well as those in the general population." The subdivision is more than 30 miles from Halema'uma'u.

Residents were advised to leave the area, and an evacuation center was set up at the Na'alehu Community Center. The county lifted that advisory at 10 a.m.

The most recent measurements of emissions at the crater found that the volcano was generating some 970 metric tons of sulfur dioxide on Tuesday, about five times the normal emissions.