" A bubble on the south side of the dome has risen to at least 330 feet since scientists first spotted it Sept. 30, and it was now almost as tall as the dome's 1,000-foot summit, said USGS geologist John Pallister.

"The blister is a rather remarkable event," he said, saying that it infers magma is somewhere at shallow depths less than a mile below the surface.

Scientists will monitor the bulge to see how the uplift relates to the seismic activity, Pallister said."

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