The presence of hazardous materials like a pile of tires or a stockpile of chemicals in the flow's path would also trigger a mandatory evacuation order, he said. Burning asphalt was generating some smoke, but Oliveira said the wind dispersed the fumes over unpopulated areas and it didn't pose a health risk at the moment.Kilauea volcano has been erupting continuously since 1983. Most lava from this eruption has flowed south. But the lava has flowed to the northeast over the past two years. The current flow that has been threatening Pahoa began in June. It's been moving fitfully toward the town for weeks,speeding up and then slowing down.