Monday, December 03, 2012

Just Experienced Noticeable Earthquake in Anchorage, Alaska; Official Final Magnitude Now 5.8

While preparing another post, I just experienced a very noticeable earthquake here in Anchorage. It occurred around 4:43 P.M. Alaska time, and I estimate the duration to be around 20 seconds.

It started out as a gently rolling motion, then one-third of the way through, a sharp jolt which bounced the house (a mobile home) a bit. Then it gradually tapered off. No damage or any falling objects; the lights didn't flicker, and my Internet connection remained uninterrupted.

This one got my attention. Based on 20 years of living here, I'm estimating the magnitude at 5.5. Will post the official numbers when they become available.

Update #1: We now have the first official report of 5.7 magnitude from the West Coast and Alaska Tsunami Warning Center. The epicenter was 25 miles west of Anchorage and occurred at a depth of 34 miles:

Preliminary report from the West Coast and Alaska Tsunami Warning Center

Update #2: The National Earthquake Information Center has issued their own report, and say the magnitude was 5.8. They're also reporting a depth of 33 miles. This is now considered the official report. In addition, the NEIC is also reporting two aftershocks, one of 2.6 magnitude at a depth of 41 miles at 4:50 P.M., and another of 2.8 magnitude at a depth of 31.5 miles at 4:52 P.M., both at the same location as the original. I did not feel either aftershock here.

Comments to the Anchorage Daily News and KTUU Channel 2 stories indicate the extent of the quake. It was felt down south in Ninilchik, in Homer, and in Seward. One person reported on KTUU that it cracked the ice on Kenai Lake near Cooper Landing.

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