Quakes in Arizona this week were aftershocks from larger one

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Two earthquakes in northern Arizona within the past few days were aftershocks of a larger one that hit several months ago, according to an Arizona State University professor.

“This week there was a magnitude 2.6 and a 3.2 that were recorded, although my colleagues at Arizona Geological Survey say they recorded about 20 more that were even a little bit smaller,” said Ramon Arrowsmith, professor of geology in the School of Earth and Space Exploration at ASU.

Arrowsmith said the seismic activity was associated with Oak Creek fault near Sedona, and were aftershocks from last year's November 30 quake that registered as a magnitude 4.7. It was responsible for landslides on US 89A. People as far south as Anthem reported feeling it.

Hollywood's portrayal of the "big one" hitting California is depicted in the film San Andreas, which is set to hit theaters May 29. Despite the special effects, Arrowsmith said this kind of destruction from a magnitude eight earthquake isn't that far-fetched, but he also emphasized Arizona would not experience anything nearly as severe.

“We just don't quite have the faults to have the big one, and we're also not on the plate boundary, so Arizona is not getting pulled as fast,” said Arrowsmith.

But Arrowsmith says small earthquakes are actually pretty common in Arizona, and that there are three main areas where they originate.

“Kind of from south of Flagstaff, through Flagstaff to the South Rim of the Grand Canyon. That's one area. Another area in southwestern Arizona, by Yuma, and also southeastern Arizona, especially in northern Sonora where there was an important historic earthquake,” said Arrowsmith.

While rare, the largest earthquake ever recorded in Arizona was a magnitude 7.4 back in 1887, south of Douglas.

"It was ringing bells in Albuquerque, Phoenix, Las Vegas. It caused damage in Tucson, Tombstone,” said Arrowsmith.

Three magnitude 6 earthquakes hit in the early 1900s just outside of Flagstaff, and more recently, in 1993 a magnitude 5 hit the South Rim of Grand Canyon.

“I think it's important to just always be prepared. We say drop, cover and hold on,” said Arrowsmith. “So don't run outside. Just get under something, let the shaking end, and check on everyone.”

According to Arrowsmith, small aftershocks from the November 30 quake may continue for the next several months.