Swarm of small earthquakes continues in northwestern Arizona

A swarm of mostly small earthquakes in a remote part of northwestern Arizona has entered its fourth week its fourth week, gently shaking the sparsely populated area while piquing the curiosity of scientists from afar.

There have been more than 40 small quakes near the Arizona-Nevada line south of Littlefield since the swarm started March 28. They’ve ranged from a magnitude 0.4 on April 9 to a Sunday evening quake of magnitude 3.7.

Mohave County Sheriff’s Office dispatchers were unaware of any reports of injury or damage, spokeswoman Trish Carter said Tuesday.

The Sunday evening quake was felt in Littlefield, located along Interstate 15 in the Arizona Strip region north of the Grand Canyon, and in Mesquite, Nevada.

The Arizona Geological Survey said the swarm is occurring along the boundary between the Colorado Plateau and a region with active faults, the Basin and Range Province.

Michael Conway, chief of the survey’s Geologic Extensive Service, said northwestern Arizona and southeastern Nevada have had swarms before but that the extent isn’t clear because there weren’t many seismometers in the region.

Ken Smith, manager of the Nevada lab’s seismic network, said the swarm has been monitored with the help of University of Utah sensors in southwestern Utah and that the state systems share data through a national system.

Smith said swarms tend to slowly run themselves out.