Yellowstone National Park earthquake shakes hottest and oldest geothermal area

A minor earthquake has hit Yellowstone National Park, shaking the hottest and oldest geothermal area in the region.

The magnitude 3.9 tremor hit near Norris Geyser Basin in Wyoming on Tuesday (Jan. 28) at 6 p.m. Mountain Standard Time (8 p.m. EST).

"The earthquake is typical of the Yellowstone region and not a sign of any significant unrest, and it was reported felt by a few people in the Yellowstone region," the U.S. Geological Survey (USGS) wrote in a Facebook post.

Scientists rate the size of earthquakes with the magnitude scale. Earthquakes with a magnitude of around 4 are minor quakes that can be felt by humans. The earthquake in Yellowstone was normal for the region, according to USGS.

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Yellowstone is seismically active and experiences about 1,500 to 2,000 earthquakes each year. Most of these shakes are up to magnitude 2, but some are higher, like the one in Norris Geyser Basin on Tuesday.

Norris Geyser Basin is the hottest and oldest geothermal area in Yellowstone and home to the tallest geyser in the world, which shoots hot water and steam 300 to 400 feet (90 to 120 meters) into the air, according to the National Park Service. The basin sits at the intersection of two faults — fractures between two blocks of rock that can slip past one another and cause earthquakes.

The largest earthquake ever recorded within the park struck close to Norris Geyser Basin in 1975. That earthquake was a magnitude 6, but there was little damage and no injuries reported at the time, according to USGS's Yellowstone Volcano Observatory.

There are about half a million minor earthquakes within the 2.5 to 5.4 magnitude range every year worldwide. Those in the magnitude 6 range usually number about 100 and can cause significant damage to populated areas. Scientists consider less-common magnitude 7-range earthquakes to be major earthquakes, while the exceptionally rare magnitude 8 earthquakes — averaging about one per year or every other year — are great earthquakes, according to Michigan Technological University.

The largest recorded earthquake in U.S. history had a magnitude of 9.2. Hitting Alaska in 1964 and triggering a tsunami, this great earthquake resulted in the deaths of 128 people and about $311 million in property loss.