In a region accustomed to seismic activity, a magnitude 7.2 earthquake rocked the offshore Alaska Peninsula on July 15 at 10:48 p.m. Alaska time.
The earthquake occurred three years to the month after the magnitude 7.8 Simeonof Earthquake that struck the same area.
The epicenter of the 7.2 earthquake was 50 miles south of Sand Point, approximately 100 miles southeast of the 7.8 event in 2020, and at a depth of around 20 miles.
Shortly after the earthquake struck, a tsunami warning was issued as a precautionary measure on Saturday night. It was downgraded the warning to an advisory level about an hour later, and ultimately canceled it just before 1 a.m. The recorded tsunami waves reached a maximum height of only 0.5 feet in King Cove and Sand Point, posing no significant threat to coastal communities.
The ground shaking resulting from the earthquake was felt across multiple communities on the Alaska Peninsula and the eastern Aleutian Islands, with an intensity reaching level V, considered moderate on the Modified Mercalli Intensity Scale.
The Alaska Earthquake Center anticipates the earthquake will generate its own aftershock sequence, following the pattern of previous moderate-sized earthquakes in the region. As of now, the largest aftershock, measuring a magnitude 5.0, occurred three minutes after the main shock.
Just as a reminder, for those who are geologically and seismically ignorant, the Anchorage and upper Cook Inlet area is at absolutely NO danger from a tsunami, ever, from ANY earthquake, no matter how strong or where it occurs. Cook Inlet is simply far too long, and too shallow, to allow the propagation of a tsunami, contrary to any potential kneejerk squawking of your personal tracking device (aka ‘phone’).
Thankfully. The destruction alone in 64 was enough and would result in a much greater loss of life and infrastructure in todays anchorage.
Yet the powers that be, who know this information, still send out meaningless alerts to people who do not need the alert…
Those in power gotta keep the sheep corralled by their irrational fears, Steve-O!
And it invariably works.
Jefferson, it’s called AdFearTisement… brought to you from the Government Ad Council, the same folks that want you to get jabbed with an experimental gene therapy and worry about Climate Change causing Sea Levels to rise enough to flood your mountainside property. Hey, wouldn’t that be kind of like a Tsunami? Huh.
Another thing that’s been bugging me is why isn’t Climate Change an issue in China? Maybe because it’s already a Totalitarian Society? You think? John Kerry is on his way over to kowtow to Xi even as we speak, hopefully he will get the Chi-Coms to be as concerned about Climate and their number one position regarding belching of carbon as they are about their apparent genocide of their Uyghur population. I remain Hopeful!
I gotta go now to recycle my plastic water bottles in order to save the planet, TTYL
I did not know that about the Cook Inlet. Interesting. I wonder if there are other places around AK that are similarly not tsunami prone.
Probably not very many, Fire — Cook Inlet is fairly unique, by Alaskan standards, in that regard.
Tsunamis can only travel significant distances in very deep water, so once they hit shallower waters, they start to pile up and rise above the normal sea level, significantly dissipating their energy in the process. That is why even the strongest tsunamis, such as the 2004 Indian Ocean tsunami, can only travel a handful of miles inland, even over perfectly flat ground.
Keep in mind the Seward is deep water, so is not included in that safety zone.
Likely large parts of Bristol Bay, Western Alaska, and Northern Alaska are not prone to tsunamis due to the large amounts of shallow water around those areas.
Jefferson information is sound. But his delivery is very condescending. He likes people about as much as phones.
Sorry, Jimbo, I did not mean to come across as condescending.
But one would think that anyone living in Alaska — or at least, anyone living in Anchorage — would have some basic fundamental knowledge of the threats that they face living here, or more to the point, the lack of particular threats that they face living here.
In actual fact, though, you are exactly correct on one matter: I like people vastly more than I like idiot-phones.
Huh. I didn’t think Jefferson was being condescending. All the information from everyone was fascinating. Being in the Interior I’m ignorant of but also impressed with coastal AK facts.
Never say never. The 1883 flank collapse from Augustine put a 6 m tsunami into English Bay, 80 km NE of it. There was a smallish dome collapse during the 2005 – 2006 eruption that didn’t put debris into the water. A large enough flank collapse on the N flank could make things interesting in upper Cook Inlet. The 20 m bluff around most of the Inlet provides some protection. Cheers –
‘https://www.gi.alaska.edu/alaska-science-forum/augustine-volcano-tsunami-generator
Old Girdwood was flooded to 15 feet during the 64 quake. Just saying.
We were camped on the beach in Whittier. The alarm went off on my phone and other campers. We packed up and the tunnel people let us out even though it was after the 11:15pm cut off. Didn’t want to take a chance it was a false alarm and be stuck with the tunnel closed. Calling wolf too many times makes these alarms useless.
It might not of been a huge tsunami, but those waves that came in were strong enough to push those boats around, Person in back ground sounds like he was catching his breath after running to higher ground.
In 1946 the Scotch Cap lighthouse was completely erased in a matter of moments by a presumed seismically generated tsunami. That was on Unimak, roughly 100mi from Sand Point. If you’re unfamiliar here’s a link (remove the lead apostrophe):
‘https://www.gi.alaska.edu/alaska-science-forum/demise-scotch-cap-lighthouse
Scotch Cap. Great info! Built only 35 to 45 feet above the water with the light itself at 90 feet. The tsunami estimated at 130 feet. I’m curious if Scotch Cap light location was not known for large waves, excluding the tsunami wave of 46, because it seems a poor location for a lighthouse. Perhaps there was no other better location.
It happened in 2020 and again in 2021 and NOW again?? Nothing really happens, except for the over anxious people madly rushing off the Homer Spit. I was there in 2020..All in the same month and nearly the same week.. When the Big one REALLY hits, people will be too numb to rush when they really need to.
Good point, KC, about the government that cried “Wolf!”
Those of us in the Inside Passage are pretty safe, excluding Sitka.
The twists and turns that wave would have to do makes it profoundly remote it could do any real damage.
If one is big/bad enough to charge down the Gastineau Channel, we’re all doomed anyway, so why worry?
I told my wife the same thing about Cook Inlet when her iPhone sounded off … and echoed the comments as seen here, regarding fear-mongering from the gov’t. Yet the entire west side of the Kenai Pen was alerted by the official Tsunami Map. Homer, YES. North of Ninilchik, NO. I thought, “What amateurs are running the show over there?” Maybe to scare off Dip Netters? I keep a FLIP PHONE myself, so I will have far less distractions from threads, links, emails and gov’t panic. Anyone remember the Covid Alerts in 2020?
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