Sunday, January 6, 2013

Major Alaskan Earthquake Yesterday


There was a major earthquake in Alaska yesterday, 7.5 on the Richter scale (later downgraded to 7.2), which caused the government to send out a scary tsunami warning about "major inundation" of the coastline. But only a few waves were generated, thank goodness. Most of Alaska's population lives near the southern coast and there are so many islands and inlets where fishermen keep their boats, that the worst case scenario might look similar to the Japanese Tsunami. I hope people go to higher ground every time even if some of these warnings seem like the government is crying wolf.

Interesting that there were "loud noises" reported on Thursday which local authorities couldn't explain. Of course there are always small earthquakes rumbling in Alaska every day, so maybe the locals tune it out unless they hear a rumbling. But those could have been fore shocks of the big one.

Booming noises heard in Alaska on Thursday
Southcentral Alaska authorities didn’t have any immediate cause for a loud booming noise heard Thursday night and reported by Channel 2 viewers, but seemed to rule out sonic booms from aircraft in responses Friday.
Reports of the sounds were posted on Channel 2’s Facebook page Thursday evening by people ranging from Eagle River to the Mat-Su Valley. Some reports placed the phenomenon between 8 p.m. and 10 p.m. Thursday, with Channel 2's Late Edition airing a brief update on the reports. Viewers' descriptions of the sound varied, but those who heard it generally agreed that it was a strong and persistent noise.

“I live in Peters Creek and I heard several loud noises outside and then muted the television,” Channel 2 viewer Rachel Lee wrote. “After about a minute of silence, there was a rumble and my chandelier started to shake. I thought it might have been an earthquake but I looked online and there weren't any listed at that time; it was 8:05 p.m.”

“About the only thing I can compare it to is someone going down a dirt road really fast,” viewer Deb Spaulding wrote. “(I)t was that sort of rumble.”

“I was in the garage and I heard it. It (lasted) for a while,” wrote viewer Michelle Thomas Hanks. “At first I thought it was the wind until I stepped outside… My (neighbor’s kids) looked for what was making that loud noise and they could not see anything just kept hearing the loud noise.”

John Pennell, Joint Base Elmendorf-Richardson’s chief of media operations, says the base wasn’t flying any of its supersonic fighter jets capable of causing sonic booms Thursday night, with only subsonic C-17 Globemaster III transports flying until 9:30 p.m.

From the Alaska Dispatch
Tsunami advisories were briefly in place from the Washington state and Canadian border to the Kennedy Entrance, 40 miles southwest of Homer, but those advisories were cancelled shortly before 1:30 a.m. Saturday. Also cancelled was the portion of the warning in effect north of Cape Fairweather stretching to Cape Suckling, 75 miles southeast of Cordova.

According to the Alaska Earthquake Information Center, which was under heavy traffic Saturday morning, the quake was initially measured at a magnitude of 7.2, at a depth of 14 miles and 67 miles west of the community of Craig. The U.S. Geological Survey put the quake 63 miles west of Craig and initially estimated it at magnitude 7.7, later downgraded to 7.5. The depth was also estimated at a shallower 6.2 miles.
. . . A small tsunami was observed in the community of Port Alexander shortly after 1 a.m., the Alaska Tsunami Warning Center reported. That wave height was only a half-foot above the norm. Sitka experienced an even smaller wave.
. . . Also briefly on the list for a potential bump in wave height was the area surrounding Kodiak Island, where the Shell drill rig Kulluk has been grounded in shallow water off the coast of the nearby Sitkalidak Island since New Year's Eve.

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