Honaunau resident Frank Commendador is concerned about isolated residents in his neighborhood who might not hear a distant siren or get the word if there is an evacuation because of approaching lava.

"Basically I'm asking the question, if the majority of the people have P.O. boxes and no real street address, how are we to find everybody should something occur?" he said. "For the people who don't have cars, is somebody going to pick them up?"

Big Island Mayor Harry Kim, who served 24 years as the island's Civil Defense director, said that if there is an eruption, the county will provide residents with as much advance warning as possible and begin whatever evacuation procedures are necessary.

"At this point I think we may be counterproductive in terms of causing undue anxiety," Kim said. "I feel that all our responding agencies are very aware" of what needs to be done.

"This is where the monitoring is critical," he said. "It is hoped that nature, or Pele, will give us a little more advance notice as far as tremors and those things that (scientists) will monitor."

Scientists at the U.S. Geological Survey's Hawaiian Volcano Observatory have been collecting data showing a slow inflation of Mauna Loa for more than two years, since May 2002. Scientists interpret the swelling as a sign the reservoir inside the volcano is probably filling with magma.

Scientists also have puzzled over a long series of hundreds of relatively small but deep earthquakes that began during the summer. Since July, there have been 1,250 earthquakes under the summit and the adjacent part of the southwest rift zone. In the seven-day period that ended Wednesday, 188 earthquakes were recorded.

The seismic pattern is unlike anything scientists have recorded there before.

"Clearly, Mauna Loa's doing something," but scientists don't know exactly what and haven't yet seen the kind of precursors observed before the 1975 and 1984 Mauna Loa eruptions, said Jim Kauahikaua, scientist in charge at the observatory.

"I'm glad that it's got people's interest, but don't make too much of it — yet," he said.

Before the 1984 Mauna Loa eruption sent lava toward Hilo along the northwest rift zone, there was a swarm of intermediate-depth earthquakes and a gradual increase in the number of shallow earthquakes. That hasn't happened yet, although there is no guarantee the next eruption will follow the same pattern as in 1984.

Scientists also expect to detect increases in the telltale volcanic gases at the summit before the next eruption, but that hasn't happened.

Gases such as sulphur dioxide are released by magma as it approaches the surface, giving strong hints of increased activity underground.