Trio of quakes rattle Phoenix area: How common are Arizona temblors?

A string of earthquakes shook parts of central Arizona Sunday night, with the largest of the tremors – at magnitude 4.1 – felt in a number of cities across the region.

A magnitude 3.2 quake struck at 9 p.m., followed by the strongest temblor at 11:29 p.m., the US Geological Survey said. Another 4.0 quake hit about 20 minutes later. All three ranged from between 3 to 6 miles in depth, with the epicenter near Black Canyon City, about 45 miles north of Phoenix.

"I just heard this rumble and this movement and I thought it was my dog falling off the bed," said Lauren Kuby, a city councilwoman who lives in Tempe City, just outside of Phoenix, to news outlet AZ Central. “It felt like a rumble and a slight movement and then like a thud.”

While earthquakes are less common in Arizona – which is removed from the major West Coast fault lines that run through neighboring California, Nevada, and Utah – the state’s Broadband Seismic Network (ABSN) seismometers still record hundreds of earthquakes each year, according to the Arizona Geological Survey.

“Earthquakes in Arizona are not as common as in California where the San Andreas fault forms the boundary between the North American and Pacific tectonic plates,” the AGS wrote in a 2012 report. “But earthquakes occur throughout Arizona and communities in central and northern Arizona have recorded damaging earthquakes.”

The first damaging quake to be documented within the state’s borders occurred in 1906, just months before a 7.8-magnitude earthquake struck San Francisco. The Arizona temblor was felt most violently at Flagstaff, 115 miles north of Phoenix.

The number of earthquakes recorded in Arizona have increased over the years, in part due to improvements in technology and seismic data. Between 2009 and 2012, Arizona State University researchers documented more than 1,000 quakes across the state.

Still – though the USGS website recorded responses from people in suburban areas around Phoenix who reported feeling at least one of the tremors – Sunday’s quakes were relatively less significant than previous ones, and caused no damage or casualties.

“In general, it’s relatively small,” USGS geophysicist Zachary Reeves said of the peak earthquake Sunday, to AZ Central. “If people are in bed then people may not even be woken up by it.”

This report contains material from The Associated Press.