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[OM] Shakes Rattles Rolls

Subject: [OM] Shakes Rattles Rolls
From: Ken Norton <ken@xxxxxxxxxxx>
Date: Mon, 24 Dec 2018 15:15:11 -0900
Just a little bit of an earthquake update. I've been insanely busy
this month with end-of-year work tasks so I haven't been very social
media minded. Among other things.

We're still getting the occasional heavy jolt or shake, but they're
getting farther between and mostly just the low-grade stuff below 3.0
that might wiggle the water in the glass but mostly is just background
noise. The stuff between 3.5 and 4.0 do get our attention, but nothing
to worry about.

The house damage is interesting and we keep finding cracks and stuff
out of place or kilter. It definitely got shook hard and one of the
shear walls popped out a bunch of construction staples. There are
sections of siding that have popped out a bunch too. No structural
damage has been found yet.

The office building is another story. It's probably a 50/50 chance
that the building may never be occupied again. They found the cause.
During construction in the 1980's, there were a number of beams that
weren't welded properly. A number of them got tack welded, but were
never finished up. Those not only broke, but the loss of integrity
caused other welds and beams to crack and break. How these bad welds
passed inspections throughout the years is anybody's guess. The
building withstood every earthquake up to this one. It was located in
an area prone to soil liquifaction and the specific frequency of the
shaking in this earthquake caused the entire place to turn to Jello.
Based on the type of damage to the building and the structural
failure, it may not have lasted much longer. Less that 15% of the
entire building complex is considered "safe" right now. There are
several beams that are actually held up on one end or by the trusses
connected to them.

When the quake hit, it started out for a couple seconds with the
standard type of motion but it quickly changed to a pattern and
movement that nobody felt before. Crazy thought, but when I went under
the table, I thought to myself that the table would be fine for
protecting me from the falling ceiling tiles and lights, but it
wouldn't help against a steel beam coming through the ceiling. Little
did I know that the beam above my head just happened to be one that
failed. An HVAC on the roof came through the roof and landed on a desk
just several feet over from where I was at. (That desk got flattened).

Honestly, I kinda doubt that we'll ever occupy that building again. I
think it's probably going to get town down. If not, there will be a
lot of extensive steel work to repair and reinforce all the corners.
The interior, which was brand new in the past two years has to be
nearly 100% redone. Too much water damage and all of the ceilings will
require full reconstruction.

One earthquake analysis I looked at says that the slip during the
event was six feet by up to 19 miles, with the duration of the slip at
the epicenter of about 15 seconds. The long duration earthquakes are
caused by a longer rip distance. 19 miles in length kept the duration
down. The 1964 quake's fault slip occurred over a length estimated at
200 miles or more. That's why that one lasted for five minutes.

Otherwise, we're fine. At the current rate of dissipation, it should
continue to settle down and we'll be back to normal boring Alaska life
in a few more weeks.

AK Schnozz
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