Rock and roll review: The year in earthquakes

(3-minute read) 2018 WAS A RECORD YEAR FOR ALASKA 

The Alaska Earthquake Center says that there were 55,000 earthquakes in Alaska in 2018. The figure is not exact, of course. The center is still assembling the data.

The histogram chart above made by Lea Gardine of the Earthquake Center shows daily earthquake counts. The pie chart indicates how much energy the Nov. 30 quake released compared to the other 49,999, give or take a temblor.

It wasn’t just your imagination — 2018 really did set a record for Alaska earthquakes.

The previous high was set in 2017, but that record — 42,989 — was established due to the 157 new monitoring stations in place, collecting more data in remote parts of the state, especially in the north and west.  Before that, the record was set in 2014 with 40,686.

The expanded monitoring network increased the total in 2018 as well. But even taking the new monitors into account, it was a rock-and-roll year, and it included two large earthquakes: a 7.9 magnitude quake in the Gulf of Alaska off of Kodiak last Jan. 23, and a 7.0 quake in Southcentral on Nov. 30.

“This was an endurance test for our analysts, who manually check the waveforms for every earthquake and scan the data for earthquakes the automatic system missed. Their work is largely invisible to the public, but they deserve special recognition for what they accomplished this year,” the center wrote in its year-end summary, which is linked here.

The Top Ten Hits

In 2018, Alaska had the top 22 earthquakes in the nation. The top ones were:

1. M7.9 Jan. 23 Offshore Kodiak
2. M7.0 Nov. 30 Anchorage
3. M6.6 Aug. 15 Tanaga Island
4. M6.4 Aug. 12 southwest of Kaktovik
5. M6.3 Aug. 22 Tanaga Island
6. M6.1 Aug. 12 southwest Kaktovik
7. M6.1 Dec. 30 Cold Bay
8. M5.9 Aug. 25 Chagulak Island
9. M5.8 July 18 southwest of Sand Point
10. 4 tied at M5.7, including the largest aftershock from the Nov. 30 Anchorage quake

(Note that in some cases, the linked event pages have outdated magnitudes.)

UNUSUAL: 6.4 KAKTOVIK EARTHQUAKE

The center noted that the most unusual earthquake, from a seismological standpoint, was the Aug. 12 6.4 magnitude quake in the Sadlerochit Mountains, 52 miles southwest of Kaktovik and 25 miles south of the Beaufort Sea coast.

It was the largest ever recorded north of the Brooks Range. It also had an after shock of 6.0 on the same day, which was the second largest earthquake ever recorded in the region. Two big quakes on the same day in the same place is, indeed, unusual. They were both felt as far south as Fairbanks.