Why did thousands of 1959 aftershocks filter Yellowstone 60 years later?


A group of thousands of small earthquakes sneaking under Yellowstone National Park in 2017 and 2018 are probably the long-awaited aftershocks of a much larger earthquake that struck 60 years ago.

In an April 30 article published in the journal Geophysical Research Letters, researchers studied the seismicity of around 3345 earthquakes that occurred near Maple Creek in Yellowstone, in the northwest corner of the park, from June 2017 to March 2018. This small earthquake, digging waves seismic in the park on the same fault line in the same direction as the wave behind the Hebgen Event Lake – the 7.2 magnitude Mammoth earthquake recorded 28 people in 1959 and killed.

The team did not see signs that the accumulation of earthquakes caused by the movement of magma under the park, what they were rumbling off was actually a series of seismic aftershocks that made six decades.

“These types of earthquakes are very common in Yellowstone,” said study researcher Keith Koper, director of the University of Utah. However, this crowd is “a little longer and has more events than usual.”

How extraordinary is an earthquake after 60 years? This is unusual, according to the authors of this study, and similar cases have occurred in North America. An earthquake measuring 6.9 hit the upper part of Bora, Idaho in 1983 still produces aftershocks as written by researchers in 2017, and shows that under certain conditions aftershocks can continue for hundreds of years.

Unlike floods, hurricanes and other natural disasters, earthquakes do not occur as a single event in time, “said Koper, but can evolve over decades or centuries.

While about half of the Maple Creek miniature earthquake saw waves as collisions from 1959, half, which seemed to pass a little further south, appeared to be bound by natural activity in the magma pit under the park, the researchers wrote.

Yellowstone remains an eruption of seismic and volcanic activity that often goes hand in hand. Many parks are located above the large volcanic caldera, which is responsible for routine eruptions of favorite geysers such as Old Faithful. The large volcano in the park erupted three times in the last 2,100,000 years and, according to some scientists, a fourth eruption is estimated to occur.

Fortunately, according to the authors of the new study the aftershock earthquake in the Hebgen Sea is located outside the Yellowstone caldera and may not be related to volcanic activity. If you are looking for a sign of a curse, find it elsewhere – maybe an 80-year-old artificial trash that was removed from the nearest geyser hot spring last year.

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