At 1:49 a.m. ADT (9:49 UTC) on Monday, June 28, 2004, a strong earthquake occurred in the Queen Charlotte Islands region near Alaskan/Canadian border. This earthquake was situated 112 kilometers (70 miles) southwest of Craig, the nearest population center. It was felt strongly in southeastern Alaska and northern British Columbia. No injuries and only minor damage have been reported. Based on the Alaska regional seismic network data, the earthquake location (red star) is at 55.072N and 134.532E at a depth of 20 km, the estimated magnitude is 6.8. This earthquake is the largest to occur in the Queen Charlotte Islands region since the magnitude 6.3 earthquake on February 17, 2001. The M6.3 shock was located at 53.987N and 133.612W, 135 km (84 miles) south of the recent M6.8 event.

The M 6.8 earthquake occurred on the Queen Charlotte fault system. This is a strike-slip fault which marks the boundary between the Pacific crustal plate to the southwest and the North American plate to the northeast. The largest recorded earthquake that had previously ruptured this section of the fault was the magnitude 8.1 earthquake on August 22, 1949. The elastic-wave radiation pattern of the M6.8 event is consistent with the earthquake occurring as the result of right-lateral strike-slip faulting on a northwest-striking fault - as expected from the tectonic situation of the earthquake.

Ten aftershocks (red circles), magnitude 2.3 or larger, have been located by AEIC within 24 hours of the mainshock occurrence. The largest aftershock occurred at 8:44 a.m. ADT on June 28 (16:44 UTC) and had a magnitude of 3.8. Due to the sparse station coverage (yellow triangles) in the area the earthquakes have large location uncertainties. The nearest seismic station is located 140 km away from the epicentral region of the M6.8 event. Therefore, only aftershocks with magnitude of about 3 and greater can be located.

List of located aftershocks:

        DATE                    LAT       LON           DEPTH    MAG      RMS     SEH     SEZ      GAP       PHASES    MINDIST   QUALITY
yy mo dy       hh:mn:sec        DEG       DEG            km      ML       sec.     km      km      deg         P,S        km


2004/06/28  09:49:51.366 	55.072 	 -134.532 	19.9  	 6.8  	  1.72 	  60.30	  69.25	  190.2 	83 	226.06 	 D 	 
2004/06/28  10:12:46.105 	54.897 	 -134.465 	 2.0  	 2.9  	  1.14 	  13.60	   2.41	  203.1 	14 	143.78 	 D 	 
2004/06/28  10:22:11.164 	55.066 	 -134.645 	10.0G 	 3.5  	  1.38 	  39.28	      -	  188.5 	11 	165.46 	 D 	 
2004/06/28  15:49:54.490 	55.133 	 -134.964 	10.0G 	 3.5  	  1.34 	  93.08	      -	  331.5 	 7 	215.05 	 D 	
2004/06/28  16:44:24.561 	54.732 	 -134.715 	10.0G 	 3.8  	  1.37 	  16.54	      -	  193.6 	16 	143.78 	 D 	  
2004/06/28  23:08:17.746 	54.969 	 -134.967 	 9.7  	 3.0  	  1.40 	  32.53	   6.77	  193.0 	13 	172.80 	 D 	
2004/06/29  01:51:02.314 	55.125 	 -134.261 	10.0G 	 3.0  	  1.68 	  32.52	      -	  179.8 	10 	155.45 	 D 	
2004/06/29  04:49:32.982 	55.146 	 -134.264 	18.0  	 2.3  	  0.73 	  80.71	  48.03	  192.0 	 8 	157.56 	 D 	 
2004/06/29  13:53:54.247      	55.107   -134.127       18.0     3.3      0.75    21.46   75.85   176.4         13      149.11   D        
2004/06/29  17:36:01.247 	54.931 	 -135.298 	10.0G 	 3.2  	  1.03 	  35.42	      -	  201.7 	 9 	187.03 	 D 	  
2004/06/30  00:04:00.417 	54.575 	 -134.852 	 9.2  	 3.5  	  1.40 	  12.10	  26.32	  198.3 	18 	141.88 	 D