Scientists monitoring Mount St. Helens confirmed Wednesday that magma is on the rise and "re-pressurizing" the volcano in southwest Washington.
However, they also stress there are no signs of an imminent eruption.
Scientists keep tabs on Mount St. Helens with seismometers and very sensitive GPS instruments. Earthquake activity is still low, but the GPS stations are more revealing. They show the volcano swelling modestly.
Seth Moran, a U.S. Geological Survey seismologist, says this is consistent with magma moving up from depth to recharge the reservoir beneath the volcano.
"We don't know when it is going to erupt next," he says. "What this is telling us is that it is getting ready. It could be years. It could be decades until it finally does. But it is getting ready again."
Moran says Mount St. Helens will tell us when it's about to blow with swarms of earthquakes and much more swelling than we're seeing now. He says the pace of refueling seems to be slower this time than before the last eruptive cycle. That ended in 2008.
Coincidentally, the National Science Foundation and USGS have funded a major study to begin this summer to image the magma plumbing beneath Mount St. Helens.