It is a valid concern, as Yellowstone is centered over the largest supervolcano in North America. But park scientists say there are explosions of another kind to be concerned about that are more likely to occur in our lifetime.

The ground has settled at Yellowstone Park after about 900 earthquakes occurred here between December 26 through the first week of the new year. An event referred to as an earthquake swarm.

"We've had larger swarms in the past, larger earthquakes, but the fact this is in Yellowstone Lake and it's releasing a lot of energy is very interesting to us," said Hank Heasler, park geologist.

The recent earthquake swarm caused no property damage to the nation's first park, but scientists said it could have altered some of the thousands of thermal features the park is famous for."

"We wanted to depict what was happening over time," said Cheryl Jaworowski, park geologist, pointing to a map she created hanging in her office. The map shows the northward movement the recent swarm was taking in Yellowstone Lake. Jaworowski used circles to represent the quakes, and on the map you can see how they came very close to disrupting a large thermal region.

"Might of we had a hydrothermal explosion, basically like a geyser eruption but involving a lot of dirt and rocks, could it have not caused any change," speculated Heasler. These are questions still being studied.

The recent earthquakes caused an eruption of volcanic dooms-day sayers to take to the internet. "We don't see any evidence of volcanic activity associated with this earthquake swarm."

The Yellowstone Volcano Observatory is a group of scientists, including Heasler, charged with keeping an eye on the situation. "Technology has improved greatly for the earthquake monitoring, satellite sensing of volcanic activity and we just do not see any of those indicators currently in Yellowstone," said Heasler.

The YVO streams live seismographs on its website. Heasler said this scientific data can be misinterpreted. For example, many people confused constant small pulses on a January seismograph as harmonic tremors, which are indicative of a pending volcanic eruption.

"So, part of the web excitement with all this is that people thought they were seeing harmonic tremors when actually it was just simply wind noise," said Heasler.

The earth may be settled beneath Yellowstone for now, but it is never quiet. "These features change daily, the thermal activity, the deposition of the rocks, Yellowstone is extremely dynamic," said Heasler. That is what keeps the doomsday sayers, and the millions of visitors coming back for more. "It's Mother Nature, what are you going to do," said Peter Janker, park visitor from New York.

Heasler said it would not be out of the ordinary for this swarm to pick back up again. The swarm in 1985 lasted for about three months. Scientists are still studying the cause of this latest swarm.