Last night, a M4.7 earthquake occurred between Flagstaff and Sedona (just west of Munds Park). I hope it was not too scary for my friends and colleagues. It sounds like it got their attention! I agree with Professor Brumbaugh from NAU who said: "It was a large enough earthquake to be felt, but not quite large enough to really get too concerned about" (link).
The USGS shakemap indicates that light shaking is reported from north Phoenix to north of Flagstaff. If you know someone who felt it; tell them to go to that site and record their perceptions.
Here is the seismogram from Tucson:page on the eventyou can hear it!
The earthquake occurred in an area where there are some active faults, most notably the Lake Mary fault system south of Flagstaff. Here is the epicenter on a map of USGS Quaternary Active Faults:
Here it is with historic seismicity (from Jeff Lockridge). There was an M3.5 within a few km of this event on November 25, 2014. Geologic Map of Arizona:
USGS and it is a NE-trending mostly normal faulting event. The Earthly Musings blog has a nice entry on the Oak Creek Fault. Here is the earthquake on a compilation of active faults and earthquakes that I put together: PDF. There have been some earthquakes in that area over the years.
- Main USGS page on the event
- Arizona Earthquake Information Center at NAU
- Nice to play around with seismicity on the IRIS Earthquake Browswer
- Here is the IRIS page on the event
- A presentation of mine on possible controls on earthquakes in Arizona (crustal thickness and topographic gradients): PDF
- Interactive map from IRIS
- Small shaking at Lowell Observatory--thanks to Sumner Starrfield for the link
- Earthly Musings blog has a nice entry on the Oak Creek Fault
- blog entry from Arizona Geology on the event
- News reports:
I will continue to update as I learn more.