March 15, 2005



The Blue Ridge area of the Mogollon Plateau has been the site of a swarm of earthquakes beginning in late January 2005. The largest events have been a M4.0 on January 28, a second M4.0 on January 30, and the largest so far a M4.6 on March 2 at 5:12am local time that was felt over much of central and northern Arizona. These larger tremors have been accompanied and followed by numerous smaller earthquakes in the area that have continued up to the present. The tremors are too small to have created ground breakage and fault slip at the surface although a number of prominent faults do occupy the Blue Ridge area, including the Quayle Hill fault that crosses State Route 87.

The swarm activity presently occurring mirrors the same type of activity occurring in this area in 1989. The 1989 swarm began on April 18, 1989 with a M3.4 tremor and continued until September 6, 1989. More information on this 1989 swarm may be found in the Catalog of Arizona Earthquakes (1830-2005) which is on the AEIC website.

The information on the M≥4.0 tremors of the presently occurring 2005 swarm are given below along with the wave forms of the M4.6 event as recorded by the AEIC network stations.