Did you know the ground beneath is rumbling again right now? You can't feel it, but it is moving about 25 miles below us.
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"It's nothing very interesting to look at on the seismograph, it just looks like wind noise," he said.
But, for Creager and his colleagues, this is exciting stuff. Those 25 miles below us, they can watch the earth move in real time.
Scientists call this a slow tremor. It happens once about every 14 months.
They mapped it for the first time in July 2004. Even though the ground's moving beneath us again, we can't feel it. If we could measure it, it would have a magnitude of about 6.7. And that's just about what California's Northridge and our local Nisqually quakes were.
However, those happened over a period of about 15 to 20 seconds. The ground moving below us right now will occur over about 15 to 20 days.
"It's still releasing the same amount of strain energy, but it's just taking a long time so it's not felt, it doesn't do damage," Creager said.
This slow tremor started Sunday and may last another week or more. But the movement is so slight -- just a fraction of an inch -- that researchers needed a new network to track it.
EARTHQUAKE!... err, movement?
Does that mean a major earthquake could be just around the corner?
"The general consensus is that we don't really know enough about the problem yet to say anything concrete about it yet, but it's possible," Creager said, adding possible, but not probable.
