18 days after the earthquake, nearly 5,000 aftershocks and counting

From Alaska Earthquake Center
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ANCHORAGE, Alaska (KTUU) — 18 days after a magnitude 7.0 earthquake shook Southcentral Alaska, nearly 5,000 aftershocks have been registered by seismic sensors, and on Sunday, the Alaska Earthquake Center reported surpassing 50,000 recorded earthquakes in Alaska in a year for the first time ever.



Research Technician Dara Merz wrote in a Facebook post that the main drivers of seismic activity in 2018 were the Jan. 23 magnitude 7.9 Kodiak earthquake, the Aug. 12 6.4 Kaktovik earthquake, and the Nov. 30 earthquake.

As of early Tuesday evening, the count was up to 50,413 reported earthquakes.

Alaska Earthquake Center seismologists say that although the frequency of aftershocks is slowing slightly, seismic activity remains "way above" background levels prior to Nov. 30.


Cumulative count of seismic events in Southcentral Alaska, Dec. 4 - Dec. 18

Seismic events in Southcentral Alaska magnitude by time, Dec. 4 - Dec. 18

Alaska Earthquake Center Seismic Network Manager Natalia Ruppert told Channel 2 Tuesday that prior to Nov. 30, the region experienced between "a handful to several" earthquakes per day on average — the background level.

Since Nov. 30, Ruppert says the same region is experiencing an aftershock every couple minutes, all day, every day.

Of those nearly 5,000 aftershocks, only a small minority — around 120 since Dec. 4 — are magnitude 3.0 or greater, and only nine greater than magnitude 4.0 in the same time.


Cumulative count of seismic events in Southcentral Alaska magnitude 3.0 or greater, Dec. 4 - Dec. 18

Seismic events in Southcentral Alaska magnitude 3.0 or greater by time, Dec. 4 - Dec. 18

Dr. Lucy Jones, a seismologist with the California Institute of Technology, told CNN shortly after the Nov. 30 earthquake that the aftershocks won't stop for months, and maybe even years.

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