are earthquakes of that magnatude, a common occurance at the alaska site?
Quoting: Anonymous Coward 69876812 Common 1-3 times a year, yes.
Since 2013 there have been 15 quakes of 6.0 to 7.9
6.9 73km SW of Nikolski, Alaska 2015-07-27 04:49:46 UTC 27.1 km
6.7 108km NNW of Chirikof Island, Alaska 2015-05-29 07:00:09 UTC 72.6 km
6.2 96km WNW of Willow, Alaska 2014-09-25 17:51:17 UTC 108.9 km
6.0 90km NNW of Yakutat, Alaska 2014-07-17 11:49:33 UTC 10.0 km
6.3 55km ESE of Buldir Island, Alaska 2014-06-24 03:15:35 UTC 4.0 km
6.0 5km ENE of Little Sitkin Island, Alaska 2014-06-23 22:29:51 UTC 106.6 km
6.0 5km WSW of Little Sitkin Island, Alaska 2014-06-23 21:30:46 UTC 101.9 km
6.0 3km WNW of Little Sitkin Island, Alaska 2014-06-23 21:11:40 UTC 102.8 km
7.9 19km SE of Little Sitkin Island, Alaska 2014-06-23 20:53:09 UTC 109.0 km
6.1 129km NNW of Amukta Island, Alaska 2014-02-26 21:13:40 UTC 265.0 km
6.1 77km SSW of Atka, Alaska 2013-09-15 16:21:37 UTC 24.0 km
6.0 82km SSW of Atka, Alaska 2013-09-04 06:27:03 UTC 17.0 km
6.5 81km SSW of Atka, Alaska 2013-09-04 02:32:30 UTC 20.0 km
6.0 118km SSW of Atka, Alaska 2013-08-31 06:38:36 UTC 18.0 km
7.0 101km SW of Atka, Alaska 2013-08-30 16:25:02 UTC 29.0 km
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link to earthquake.usgs.gov]