A swarm of earthquakes hit near Littlefield in northwestern Arizona at approximtely 7 a.m. today, according to the Arizona Geological Survey. The magnitude (ML) 3.8 earthquake occurred at a depth of seven miles.
This is the largest of a swarm of 55 temblors that began along the remote Arizona-Nevada border on 28 March with a ML 2.1 event.
This earthquake sequence now includes three events greater than ML 3.0, 12 events greater than or equal to ML 2.0, and the remainder smaller than ML 2.0. Reported earthquake depths range from near-surface to approximately 14 km.
According to the U.S. Geological Survey, the earthquake occurred on an oblique, steeply west-dipping, normal fault.
The earthquake swarm is situated along the physiographic boundary between the Colorado Plateau and the Basin and Range Province, an area of active crustal extension and seismicity.
Officials anticipate additional small magnitude aftershocks in the wake of today’s ML 3.8 event.