Black Canyon City Earthquake Sequence

The Arizona Geological Survey (AZGS) and Northern Arizona University operate several seismometers throughout the state.  Using 15 stations, 5 of which are not currently used by the National Earthquake Information Center run by the USGS, AZGS has refined the locations for the foreshock, mainshock and the large aftershock from the November 2^nd [using UTC time - using local time, the events were on Nov. 1] Black Canyon City sequence of quakes (Table below).  The M3.2 foreshock was located at approximately 5km north of Black Canyon City at a very shallow depth, between 1-5km.  The mainshock was located approximately 18km NNE of Black Canyon City and occurred at approximately 11km depth.  The largest aftershock an Mw 4.0 occurred only 20 minutes following the mainshock at a depth of approximately 5km.  There have been multiple smaller aftershocks, but there are not enough seismometers close enough to the area of the sequence to accurately locate them.  The closest station is located near Payson at about 65km, with the Wickenburg station being 88km away.  

 

The closest known active fault is the Horseshoe Fault, located 35km SSE of the mainshock.  The Black Canyon City Sequence has not generated a quake large enough to break the surface.  Aftershocks will continue for several months or longer. 

The table below lists the revised locations, and the extent of possible errors in location, horizontally (ERH) and vertically (ERZ).

Mw	Time -UTC	Date	Lat	Long	Depth (km)	RMS (Seconds)	ERH (km)	ERZ (km)
3.2	03:59.33	11-02-15	34.11016	-112.1460	<1 .0="" p="">	0.16	1.05	5.27
4.1	06:29.66	11-02-15	34.23350	-112.12366	11.2	0.07	1.01	3.18
4.0	06:49.32	11-02-15	34.17950	-112.08633	5.19	0.10	0.83	2.77

Post from Dr. Jeri Young, AZGS

Black Canyon City quake locations refined; seismograph recording posted

We have updated the locations of last nights earthquakes near Black Canyon City, using the Arizona seismic stations in the  AZGS network.












Jeri Young also passed along this shot of the seismic signals received by the nearest station in our network, Strawberry/Payson X16A, about 65 km east of last night's quakes.   All three of the bigger quakes, M3.3, M4.1 and M4.0, are easily visible by the red waveforms at their start.

Earthquakes north of Black Canyon City shake up much of Arizona

Notable earthquakes with magnitudes of 4.0 and 4.1 hit a few miles north of Black Canyon City around midnight Sunday, with a foreshock of magnitude 3.2 at 9 pm [top, location map from USGS]   Dr. Jeri Young, who manages the seismic monitoring network run by AZGS, calculates that the location of the mainshock is a few miles further north than reported by the USGS, using information from Arizona stations closer to the events [bottom].


Reports are coming in that the two big shocks were felt from the Grand Canyon to Tuscon and widely across the region [center map.  Source, USGS]

 The M4.1 quake struck at 11:29 pm, local time, with the 4.0 quake hitting at 11:49 pm, Sunday, November 1.    Smaller aftershocks are being recorded although they have been too small to be felt.