Saturday, March 27 was the 57th Anniversary of the 1964 Good Friday Earthquake that hit south-central Alaska. The 9.2 magnitude earthquake struck at 5:36 pm AST, and the earth shook for the next 4 minutes and 28 seconds. Witnesses say that the earth roared like a freight train for that entire time.
The epicenter was 78 miles from Anchorage in Prince William Sound. It was a relatively shallow quake, with a depth of roughly 15 miles. 131 people were killed due to the earthquake, with 122 of the deaths due to the resulting tsunamis.
Seward, Kodiak, Valdez, Chenega, were all hit by tsunamis. Shoup Bay was hit by the largest tsunami with a wave height of 220 feet.
In the first 24 hours after the main shaker, there were 11 aftershocks over 6.0, with another nine over the following three weeks. Thousands of aftershocks hit the area over the next year.
A large glacial dam gave way in Southeast Alaska this summer. Known by its Icelandic term: jökulhlaup, the power of this sudden release of pent up water can be incredibly destructive.
Desolation Lake, which sits above the Lituya Glacier in Desolation Valley, collects meltwater from both the Desolation and Fairweather Glaciers. That meltwater is normally blocked by the Lituya Glacier, forming the roughly four square mile lake.
The water level suddenly dropped 200 feet.
A commercial fisherman, Jim Moore, along with his two grandsons, tried to enter Lituya Bay to fish for Chinooks in August. They should have been riding the tide into the bay, but the unusually muddy water was moving outward, and it was filled with trees and other debris. The bay was also filled with small icebergs. Moore managed to bring some of the ancient ice onboard for his coolers, then left the bay, instead of fighting the dangerous current.
It is one of the largest jökulhlaups known to have occurred in Alaska. The water found a path under the Lituya Glacier, causing a rush that would have rivaled the hourly discharge of the Amazon River. It would have lasted for several days.*
Lituya Bay has a history. In 1958, an earthquake triggered a landslide that started one of the largest known tsunamis at over 1700 feet.
This week is the 17 year anniversary of the 2002 Denali Earthquake. At a magnitude of 7.9, to date, it is the largest quake I have personally experienced.
On 23 October 2002, the Denali Fault released a magnitude 6.7 quake. That would be a foreshock of what was to come on November 3.
Highway Shift; Richardson Highway, circa 2002
After the 6.7, I remember the Alaska Earthquake Center saying that the Denali Fault was capable of producing an 8.0. Sure enough, the fault came very close.
I was at an intersection in my ’66 Chevy C-20. All of a sudden, the truck was lurching all over the place, and I found it hard to stay on the brake pedal. There were two university students in the next lane, the passenger rolled down his window and asked what the hell was happening. I said, “Earthquake”. He then promptly hit the driver on the arm and said, “I told you it was an earthquake”.
The light changed, I drove on, but had to stop at the next light. The earth was still shaking. An elderly couple had been walking on the sidewalk, and the wife fell to the concrete, the husband was struggling to stay upright by hugging a signpost. Then the shaking was over. I rolled down the other window, to see if the couple was all right. They were, and I headed home to see if there was any damage.
The quake had ruptured 205 miles of earth along three different, yet connected faults in Interior Alaska. It was the largest ever recorded in Alaska’s Interior. It was the largest inland quake North America had seen in almost 150 years.
Both the Parks & Richardson Highways saw major damage. The Trans-Alaska Pipeline moved sideways 18 feet, and rose 5 feet. The engineers had designed for the fault, and the pipeline behaved exactly as it was designed to behave. Although, it did come within two feet of its sideways movement limit.
The Denali Earthquake was felt as far away as Louisiana.
Previously, the largest earthquake Fairbanks had experienced was a magnitude 7.3 in 1937.
Spent some more time out at the lake last week. I did do some work to the place, but mainly wanted to get out and enjoy some autumn solitude.
It was quiet out there, rarely did I see more than one other boat on the water, and we seemed to do a little dance where we kept the same distance between ourselves, as we fished various areas of the lake.
I did experience my first earthquake out there. It’s an interesting feeling as the wave flows through the cabin. The quake was centered down in the Willow area, so I’m a bit surprised I felt one from that distance, but after checking their website, the Alaska Earthquake Center had it rated at a 5.2.
No fox were to be seen on this week, but there were swans. One night, I ventured out to the end of the dock past dusk. Two white blobs were visible, and with the binoculars, I could clearly see that they were trumpeter swans. One swan had its head buried under a wing, but the other was at full alert, with head held high. The lookout was not looking in my direction, but I knew it was fully aware of my presence just the same. A further inspection brought two more swans into view.
By morning, I had 13 trumpeters just past the reeds from the dock. I watched them for much of the morning. None of them seemed to be too worried about me. When they paddled off, if a boat cut across the lake, they came back to where I was sitting.
Yesterday, March 27, was the anniversary of the Great Alaska Earthquake. The 9.2 magnitude quake, also known as the Good Friday Earthquake, is still the largest earthquake to hit North America, and the second largest to ever be recorded.
“We ran out of the building, and hung onto the wire mesh fence across the street. The road looked like waves in the ocean. All of the air police trucks looked like they were dancing as they were bouncing up and down.” — Airman stationed at Elmendorf AFB, Anchorage
The 1964 Earthquake and the resulting tsunamis took at least 139 lives. The earth shook for 4 minutes and 38 seconds from the main quake alone. Girdwood and Portage sank eight feet; portions of Kodiak rose over thirty feet. Seward burned; Valdez, Whittier and Chenega were destroyed, wiped off the face of the earth by the giant waves. A 75 ton locomotive was carried 300 feet by the waves in Seward, as 14 oil tankers and 40 railcars went up in flames. The tsunami that hit the WWII port of Whittier was 40′ high.
Alaska Railroad tracks near Turnagain Arm, south of Anchorage; March 28, 1964; Photo credit: USGS
Alaska: 2018 Seismicity; Color coded by depth, Notable events labeled
The Alaska Earthquake Center at the University of Alaska – Fairbanks, has done their annual year in review for 2018. We set a record for earthquakes within the state, with over 55,000 events during 2018. That blows past the previous record of 42,989 set in 2017. The next highest number occurred in 2014 with 40,686 quakes. We had so many earthquakes in 2018 that AEC is still counting to get a specific number.
It needs to be noted, that much of the increase in numbers is due to advancing detection techniques, as well as additional recording stations. The purpose of this post, is not to imply that Alaska is about to break off from the Yukon, but to show how seismically active Alaska is.
The two largest earthquakes have set off thousands of aftershocks. The 7.9 magnitude quake in the Gulf of Alaska was the largest, followed by the now rated 7.1 near Anchorage in November.
We also had a couple of “swarms” in the northern part of the state, in the Brooks Range & on the North Slope, that lasted for months, and accounted for over 17,000 events.
The surprise earthquake of the year, happened near Kaktovik, on Alaska’s north coast. The 6.4 mainshock and 6.0 aftershock, were by far the largest ever recorded north of the Brooks Range.
On Saturday, March 9, a sudden jolt went through the cabin as I worked about the place, while listening to Minnesota hockey swarm the Michigan Wolverines. Sure enough, a 3.7 magnitude quake had occurred roughly 15-20 miles from the cabin.
A very special thanks to the Alaska Earthquake Center for the above graph and earthquake information.
Cracks along the rails north of Anchorage; Photo credit: Alaska Railroad
The railroad between Anchorage and Fairbanks remains closed from the recent 7.0 earthquake. There are several sections like the photo above, with cracks that have developed along the rails. The cracks in the photo run 2-4 feet wide, and 200 feet long.
No timetable has been given to a return to rail traffic between Alaska’s two largest cities.
The onramp from Minnesota Blvd to International Airport Road became Alaska’s most famous, with the photo of the SUV left stranded eight feet below grade.
I often make fun of Alaska’s DOT, but they have done a great job, by all accounts, getting Anchorage roads ready to handle traffic again. That interchange was rebuilt, repaved and lines painted in four days. Not bad, considering there was not an asphalt plant up & running at the time. A plant had to reopen, because everything was closed for the winter season.
An onramp to International Airport Road from Minnesota Drive in Anchorage, Alaska
Anchorage experienced quite the shaker at 8:29am Friday morning. The earthquake was initially pegged at a magnitude 6.6, but was quickly updated to a 7.0 by Friday afternoon.
A stranded SUV on the collapsed onramp
The earthquake was followed by an estimated 5.8 aftershock, and several smaller ones throughout the day on Friday. A tsunami warning was issued immediately for the Kenai Peninsula, Kodiak Island and Cook Inlet. No tsunami developed, and the warning was called off less than two hours later.
Flights into Anchorage International Airport were being diverted to Juneau or Fairbanks. Departures from the Anchorage Airport began again at 11:30am.
Vine Road, just south of Wasilla, Alaska
The epicenter of the quake was 7 miles north of Anchorage, directly across the Knik Arm from Alaska’s largest city. Depth was at 27 miles. There are reports of road damage throughout the area, and several reports of damaged buildings. Residents have called in saying that the Glenn Highway has some sections of severe damage, although there is no official word on that yet. As of this writing, no casualties have been reported.
This is the largest earthquake to hit the Anchorage area, since a 7.1 in 2016. The Friday morning earthquake was much closer to Anchorage and the MatSu Valley, so damage is expected to be higher than 2016.
As of Friday afternoon, Alaska has experienced 43,926 earthquakes in 2018.
Interior Alaskans felt the Earth move a bit on Tuesday morning. It wasn’t a big earthquake, at only magnitude 4.6, but it was widely felt at 7:18am. It’s note worthy, mainly because it has been a couple of years since I felt one pass through.
On Sunday morning, Kaktovik, which is located on the Beaufort Sea coast, woke up to a 6.4 magnitude quake. It was the largest earthquake ever recorded on Alaska’s North Slope.
Earthquakes in Alaska are far from unusual. An earthquake is detected once every 15 minutes, on average, within the state. In 2014, Alaska set a record with over 40,000 shakes. Over the past five years, the Alaska Earthquake Center has reported over 150,000 earthquakes. Of those, 31 had a magnitude over 6.0. and four went over 7.0. Seventy-five percent of all earthquakes over 5.0 within the United States happen in Alaska.
The 7.9 magnitude quake, that hit us in 2002 when the Denali Fault ruptured, is the largest I have experience. The 1964 Good Friday Earthquake was a magnitude 9.2, and it is still the second largest earthquake ever recorded anywhere on the globe.