No apparent threat, but rumble, rumble, rumble....

In the last two weeks, more than 100 mostly tiny earthquakes a day, on average, have rattled a remote area of Yellowstone National Park in Wyoming, putting scientists who monitor the park’s strange and volatile geology on alert.

Researchers say that for now, the earthquake cluster, or swarm — the second-largest ever recorded in the park — is more a cause for curiosity than alarm....

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