The Big One.
Those three words make locals along the
West Coast of North America
shudder with fear.
This area is plagued by earthquakes.
But hey,
at least they are ready.
Unlike the middle of the continent,
which is woefully unprepared
for the event that physically
rips the United States in half.
Megathrust earthquakes are the largest
and deadliest seismic events on Earth.
They occur along fault lines,
where the edge of one plate
is forced downward into the hot mantle
beneath another plate.
The Cascadia subduction zone
along the West Coast of North America
last caused a megathrust earthquake
on January 26th, in the year 1700.
And many people claim
that it’s overdue for another one.
The Cascadia subduction zone
is created by the Juan de Fuca oceanic plate
which is moving down into the mantle
of the North American plate.
It’s not a smooth movement though,
and pressure builds as the plates lock together.
And builds,
and builds.
Until the North American plate
suddenly pops on top of the
older Juan de Fuca plate.
This would trigger a megathrust earthquake,
decimating the Western coastline
of the United States.
But that’s not all.
Somehow,
the force of this terrifying earthquake
causes the thinnest part of the tectonic plate,
between California and Colorado,
to snap.
This is now an end of days
nightmare scenario.
A crack races from California
all across the United States,
splitting the nation in two.
This deafening event would
cause roads to crumble,
houses to fall into the giant crevice,
and many deaths.
Water from the Pacific and
Atlantic Oceans would rush in to fill the void,
causing 3 m (10 ft) high tsunamis
and flooding along the midline of the U.S.
Roads, power lines, and sewer pipes would tear apart.
Pipelines carrying crude oil would burst,
adding toxic oil to the massive floods.
It would take a national effort
to clean up and rebuild
both the coastline and Middle America.
Hopefully, it would bring the country together.
And after all the rubble is cleared,
we would begin to assess our new,
physically split nation.
The rift would only be about 20 m (65 ft) wide.
You’d be able to wave to your
neighbors from across the divide.
The two sides would gradually drift apart,
at about 3 to 5 cm (1 to 2 in) per year.
And the rift would eventually grow
and form a new ocean,
but for now it’s just a canal.
At first,
you would rely on ferries to shuttle
people, cars, and supplies between the two halves.
Eventually,
we would engineer segmented bridges
that could be elongated
as the rift grows.
The canal itself would be used as a
quicker shipping route between the
West Coast and Europe.
Middle America would develop shipping ports,
waterfronts, and beaches,
which would attract tourists
and new residents.
The new middle coastline
would explode in population,
with large cities growing along
this new transportation route.
The U.S. would likely stay
a single nation for a while.
It just went through a shared,
tragic event,
and the rift is only 20 m (65 ft) wide, after all.
But as the newly separated plates
began to move farther away,
differences in culture
and politics could increase.
And the possibilities of the two sides
politically splitting up
would look more inevitable.
After many years of division,
there could be a South United States
and North United States.
Now, the probability of the United States
physically breaking in two is very low to impossible.
However in Africa,
it’s actually happening
along the East African Rift.
But that’s a story for another What IF.