- The likelihood of a
major earthquake in the
Cascadia subduction zone is inevitable.
It's one hundred percent.
The question is when.
What came to my mind as I read the article
is you have the Cascadia subduction zone
stretches from Cape Mandicino up to
you know up to the middle
part of Vancouver Island,
or thereabouts and that would
be an enormously long system
to break away completely
and simultaneously.
It's more likely to rupture a part of it,
a small part of it rather
than a large part of it.
Which from a practical
standpoint may not make
a lot of difference because
you can still generate
a big earthquake with
a rupture of a minor,
small part of the fault so.
Anyway it was alarmist in
that it takes the worst
case scenario, damage all up and down this
700 mile stretch and, all
those catastrophe things.
But it's a good wake up call.
They did a good job at
pointing out that depending
on where you live the effects
are going to be different.
If you live in coastal areas you know.
In low lying coastal
areas with regards to the
Oregon coast for example,
New Port or Lincoln City
would be good examples of this.
Those areas will be
inundated by the tsunami.
If you live in the Puget
Sound lowland, you are
less likely to have a
big tsunami there but
your going to get
liquefaction of soft ground.
So different effects in different places.
If you are in a big city
the buildings start swaying,
and if you're in a small
town you know brick
structures start falling down.
So the risks vary
depending on where you are.
My guess is that it's
partially in response
to the earthquake in Japan and
the tsunami in Japan in 2011.
Prior to that event
people were thinking that
it was unlikely that it
was going to rupture,
and then a Japanese
geologist came out with
a new study that suggested
that maybe it was due for a rupture.
And then it ruptured and of
course the rest is history.
It's always good to remind
people periodically that
it doesn't pay to be complacent,
it pays to be prepared.
The problem is if you
prepare for something that
never happens, then the
next question you are asking
is why did I waste all that
time and money preparing
for something when it didn't happen?
Of course if you don't
prepare and it does happen
(laughter)
It's a different question
that comes out of that, that scenario.
So there's a lot that
you can do to compensate
for the conditions under which you live.
Building construction for example.
Construction out of
materials that are flexible,
tend to withstand earthquake
shaking much better than brittle.
So brick homes despite
what the three little pigs
might have said, a brick
home is not as good as
a wooden home or a straw
home for that matter.
Problem with a straw
home of course is that
it catches fire and then
you're cooked literally.
My colleagues over at
Memorial probably will not
want to hear this,
but Memorial Hall is built
of big quarried stone.
And it's so the motor is
brittle and it's an old
building, and stone is
you know its held together
by cement and all that stuff.
So in the 1930s earthquake
in Milton-Freewater,
Memorial's just sat there,
and nothing happened.
It was shifting all over the
place but Memorial was fine.
So ten years ago or so they
did a seismic retro fit.
Changed the foundation
did things to make it
seismically safer, so
I fully expect that the
next earthquake that happens
Memorial is going to fall over.
(laughter)
So flexible materials, sometimes they,
even in skyscrapers
where the super structure
is steel, they'll put
flexible joints in there.
So if you look in a big building even
in a windstorm if you're
up in the space needle
or some place like that,
you can actually feel the
thing moving in the windstorms.
It's kind of eerie but that is
amplified in an earthquake,
so the buildings
are actually literally
designed to do that flexing.
You can also adjust the foundations,
a lot of possibilities
to put them on bearings.
So when the ground starts
shifting the building
is not fracturing it's
just kind of rolling
back and forth on these bearings.
Any tsunami generated in
the Pacific would have to
enter the Puget Sound Basin through the
straights of Juan de Fuca, and then travel
down through the south
sound to get to Seattle
and Tacoma, and by the time it does that
the energy has attenuated
alone both of the
shorelines and then it
gets into the shallow
water and stuff like that.
So the tsunami that hit for
example Lincoln City or New Port
would probably not be nearly as severe and
once it got into the Puget Sound.
Obviously in Walla Walla we
are not going to get a tsunami,
(laughter)
that would be truly catastrophic.
That would be unrealistic, but we would
get a significant amount
of shaking in areas that
are prone to liquefaction,
river bottom land,
things like that might
liquefy, stuff like that.
So there is some potential
for some serious damage.
There's a lot of different
kinds of things that
you can do to prepare,
because there is nothing
that you can do to prevent.
Out of the question, it's just not
an option to prevent earthquakes.
When's the next earthquake?
How big is it going to be?
Those are things that we can't know.
We know that we are going
to have a big earthquake
on the Cascadia Subduction zone, we don't
know when, we don't know how big.
Far better rather than
worrying about whether
it's going to be in my life
time or not, prepare for it.
In some cases unfortunately
the genii is out of
the bottle, big cities aren't going
to relocate to high ground.
So they have to take different measures.
So you understand the
situation, and weigh the risks
what's more important to you?
To spend your life in
fear that tomorrow there's
going to be a big earthquake, or
do you like the view and you know if it's
your day to die, you're
going to die no matter
if it's an earthquake or
a truck running over you,
or something like that.
I choose not to live my life in fear,
that's easy for me to
say because I live in
Walla Walla and not
Seattle or San Francisco.
But there is a certain amount
of risk to living anywhere.
You know geology is full
of dire predictions.
If you live on this side
of a mountain you're
at risk for a land slide.
Whether that happens
today or in some other
life time is different
matter entirely and we can't
predict those things.
