Puzzling earthquake swarm near Noatak still in progress, northern Alaska

A puzzling swarm of earthquakes which started on April 18, 2014, in northern Alaska is still in progress. USGS recorded two strong and shallow earthquakes - M 5.8 at 12:00 and M 5.7 at 12:01 UTC today - about 25 km ENE of the village of Noatak.

According to USGS, there were six M5+ quakes around Noatak since April 18, 2014: M 5.6 @ 23.4 km and M 5.3 @ 33 km on April 18; M 5.5 @ 0.9 km on May 3; M 5.5 @ 16.4 km on June 7; M 5.8 @ 15.7 km and M 5.7 @ 16 km on June 16. 

They have been accompanied by more than 250 “unusually vigorous” aftershocks, Mike West, a seismologist with the Alaska Earthquake Center, said. "They all have the same cause; the same fault motion, and they occur in more or less the same place,” he said.

West said vigorous aftershocks are not uncommon, but normally they simmer down over time. The fact that this series of shakes is not losing strength is part of the reason scientists are referring to the occurrences as a swarm, rather than a sequence.

Earthquakes relieve pressure in the earth, and because these strong quakes and aftershocks are still happening, that tells experts that the stress was not fully relieved with the first set of quakes.

“In an area like Noatak, this is very unusual behavior,” West said. 

Swarms are more common around volcanoes and geothermal sites, but since there are neither in the area in question, West said seismologists are scratching their heads trying to find a comparable episode in mainland Alaska. (Alaska Dispatch)

"Although earthquakes near Noatak are rare, they are not unprecedented," Natalia Ruppert, another seismologist with the Alaska Earthquake Center, said citing a 5.5 earthquake near Noatak in 1981. (GI - Alaska)

Map showing all earthquakes near Noatak from May 16 - June 16, 2014. Image credit: USGS

1. 3.131km E of Noatak, Alaska2014-06-16 12:28:57 UTC5.4 km
2. 3.125km NE of Noatak, Alaska2014-06-16 12:23:07 UTC21.3 km
3. 5.731km ENE of Noatak, Alaska2014-06-16 12:01:08 UTC24.2 km
4. 5.842km ENE of Noatak, Alaska2014-06-16 12:00:33 UTC15.7 km
5. 3.141km E of Noatak, Alaska2014-06-16 11:38:41 UTC17.0 km
6. 3.232km ENE of Noatak, Alaska2014-06-14 16:21:05 UTC18.4 km
7. 2.927km NE of Noatak, Alaska2014-06-14 14:22:25 UTC20.6 km
8. 2.827km NE of Noatak, Alaska2014-06-14 10:38:11 UTC21.8 km
9. 2.720km NE of Noatak, Alaska2014-06-13 18:20:43 UTC34.7 km
10. 2.729km NE of Noatak, Alaska2014-06-13 13:48:45 UTC22.6 km
11. 2.732km ENE of Noatak, Alaska2014-06-12 00:47:54 UTC9.8 km
12. 2.614km NE of Noatak, Alaska2014-06-10 11:24:09 UTC12.1 km
13. 2.916km NNW of Noatak, Alaska2014-06-09 13:50:31 UTC34.5 km
14. 2.829km ENE of Noatak, Alaska2014-06-09 03:50:12 UTC10.8 km
15. 3.628km NE of Noatak, Alaska2014-06-08 02:23:32 UTC24.9 km
16. 3.127km ENE of Noatak, Alaska2014-06-07 22:18:46 UTC13.6 km
17. 2.529km NE of Noatak, Alaska2014-06-07 16:54:44 UTC15.2 km
18. 4.021km NNE of Noatak, Alaska2014-06-07 14:33:43 UTC24.2 km
19. 3.234km NE of Noatak, Alaska2014-06-07 11:53:11 UTC15.9 km
20. 3.420km NNE of Noatak, Alaska2014-06-07 10:57:51 UTC34.0 km
21. 3.130km NE of Noatak, Alaska2014-06-07 10:35:21 UTC22.4 km
22. 2.630km NE of Noatak, Alaska2014-06-07 10:30:42 UTC6.7 km
23. 2.931km NE of Noatak, Alaska2014-06-07 09:56:12 UTC0.0 km
24. 3.230km ENE of Noatak, Alaska2014-06-07 09:45:54 UTC1.0 km
25. 3.532km NE of Noatak, Alaska2014-06-07 08:59:11 UTC20.8 km
26. 3.131km ENE of Noatak, Alaska2014-06-07 08:48:45 UTC9.6 km
27. 2.729km NE of Noatak, Alaska2014-06-07 08:30:59 UTC8.7 km
28. 2.734km ENE of Noatak, Alaska2014-06-07 07:59:47 UTC8.1 km
29. 2.638km ENE of Noatak, Alaska2014-06-07 07:33:03 UTC2.1 km
30. 3.932km ENE of Noatak, Alaska2014-06-07 07:07:50 UTC4.4 km
31. 2.630km NE of Noatak, Alaska2014-06-07 06:41:00 UTC5.0 km
32. 3.735km NE of Noatak, Alaska2014-06-07 06:12:20 UTC14.5 km
33. 2.521km NNW of Noatak, Alaska2014-06-07 05:15:24 UTC27.8 km
34. 2.917km N of Noatak, Alaska2014-06-07 05:10:03 UTC40.8 km
35. 2.826km NW of Noatak, Alaska2014-06-07 05:09:40 UTC23.8 km
36. 2.728km ENE of Noatak, Alaska2014-06-07 05:06:13 UTC0.0 km
37. 5.535km NE of Noatak, Alaska2014-06-07 04:43:33 UTC16.4 km
38. 3.023km NE of Noatak, Alaska2014-06-07 03:35:23 UTC21.8 km
39. 4.432km NE of Noatak, Alaska2014-06-07 03:13:59 UTC20.2 km
40. 3.524km ENE of Noatak, Alaska2014-06-04 11:07:30 UTC10.5 km
41. 3.227km ENE of Noatak, Alaska2014-06-03 16:27:14 UTC14.8 km
42. 2.632km ENE of Noatak, Alaska2014-06-03 10:06:53 UTC13.6 km
43. 4.230km ENE of Noatak, Alaska2014-06-03 04:08:33 UTC12.3 km
44. 4.031km ENE of Noatak, Alaska2014-06-02 20:32:14 UTC14.9 km
45. 4.729km ENE of Noatak, Alaska2014-05-30 06:27:32 UTC14.9 km
46. 2.628km ENE of Noatak, Alaska2014-05-29 19:59:42 UTC14.6 km
47. 3.114km NE of Noatak, Alaska2014-05-28 10:44:46 UTC11.5 km
48. 3.035km ENE of Noatak, Alaska2014-05-24 22:02:17 UTC11.9 km
49. 2.925km NE of Noatak, Alaska2014-05-24 07:01:28 UTC20.3 km
50. 3.722km NE of Noatak, Alaska2014-05-22 23:41:43 UTC20.8 km
51. 3.120km NNE of Noatak, Alaska2014-05-22 19:02:12 UTC22.2 km
52. 2.722km NE of Noatak, Alaska2014-05-22 13:34:27 UTC26.9 km
53. 3.232km ENE of Noatak, Alaska2014-05-22 05:31:59 UTC10.3 km
54. 2.620km NE of Noatak, Alaska2014-05-21 01:59:01 UTC26.0 km
55. 2.816km NE of Noatak, Alaska2014-05-20 08:12:09 UTC16.3 km
56. 2.520km ENE of Noatak, Alaska2014-05-20 08:08:42 UTC13.7 km
57. 2.932km ENE of Noatak, Alaska2014-05-20 02:30:06 UTC14.9 km
58. 2.937km ENE of Noatak, Alaska2014-05-18 16:46:37 UTC10.1 km
59. 2.631km ENE of Noatak, Alaska2014-05-17 15:12:47 UTC10.2 km

Featured image credit: USGS