The Earth is spinning a little slower than usual right now. That could mean a lot more earthquakes with at least a magnitude 7.0 ahead in 2018.
A hiker in Iceland
straddling a spot where two of the Earth’s tectonic plates are
cleaving. Ariane
Hoehne/Shutterstock.com
2018 has been a shaky year so far.
The biggest earthquake yet happened early Tuesday morning, when a
magnitude 7.9 quake shook the ocean floor in the Gulf of
Alaska, about 174 miles off the coast.
Just three hours before that, a 6.0 magnitude quake struck less
than 25 miles from the shores of Binuangeun, Indonesia,
which sits on the Pacific «Ring of Fire,» an area prone to
frequent earthquakes and volcanic eruptions.
Tuesday’s two earthquakes were not the only big ones we’ve seen
so far — as of January 23, there have already been
three earthquakes that registered above a magnitude 7.0
in 2018. In 2017, the Earth only saw seven quakes that strong the
entire year.
Scientists say an Earth-slowing phenomenon is likely contributing
to the recent uptick in earthquakes around the globe.
You may not have noticed, but the Earth is taking things a little
slow right now. Since 2011, our planet has been rotating at
a pace a few thousandths of a second slower than usual.
Our planetary spin cycle changes constantly — it’s influenced by
ocean currents and atmospheric changes, as well as the mantle and
molten core underneath the Earth’s crust. According to
geologists Roger Bilham and Rebecca Bendick, the
Earth’s slowing could lead to more than twice as many
earthquakes with at least magnitude 7.0 in 2018 than there were
last year.
Bilham, who studies earthquakes at the University of Colorado,
told Business Insider that when the Earth’s pace lags for years
at a time, its middle contracts. That shrinks the equator, but
it’s hard for the tectonic plates that form Earth’s outer shell
to adjust accordingly.
Instead of falling in line with the slimmer waistline, the edges
of those plates get squeezed together.
This takes time for us to feel on the ground. But after five
years without many high-intensity quakes, we’re approaching the
moment when the effects of this squeeze could start to be felt
around the globe, Bilham said. He estimates the planet could see,
on average, 20 high-magnitude earthquakes in each of the next
four years, from 2018 to 2021.
A
man looks at a damaged building in Darbandikhan, Iraq, after an
earthquake there in October. Ako
Rasheed — Reuters
This lagging-Earth phenomenon isn’t prompting any earthquakes
that weren’t already in motion. Instead, Bilham said, the slower
spin adds more stress and pressure to some of these impending
quakes, pushing them to happen more quickly, especially in
earthquake-prone zones.
Bendick, who studies geologic hazards at the University of
Montana,
wrote a report with Bilham last year warning about the trend
of more frequent earthquakes, but their latest findings are still
under review.
She said it’s important to remember that the Earth’s rotation
changes all the time, for all kinds of reasons — storms, snow
buildup, and ocean patterns can all have an effect.
But Bendick said earthquake records from the past 117 years
suggest plate movement is sensitive to a special kind of 10-year
rotational slowdown like the one we seem to be experiencing now.
This is most likely because of «interactions of the lithosphere,
mantle, and core,» she told Business Insider in an email.
The researchers suspect the effects of the phenomenon may be felt
the most in spots near the equator, like Indonesia. At least four
different tectonic plates meet up in Indonesia, and the most
recent quake there happened less than 500 miles from the Earth’s
mid-line.
In the US, Alaska is home to 75% of all
earthquakes that register higher than 5.0.
The researchers say they hope city planners and politicians in
earthquake-prone zones will heed their warning and work quickly
to retrofit buildings or update emergency plans. They also advise
people to talk to loved ones about disaster preparedness.
«There is no good reason for people not to take simple steps to
be better prepared,» Bendick said.
