The Really Big One
An earthquake will destroy a sizable portion of the
coastal Northwest. The question is when.
When the 2011 earthquake and tsunami struck
Tohoku, Japan, Chris Goldfinger was two hundred miles away, in the city of
Kashiwa, at an international meeting on seismology. As the shaking started,
everyone in the room began to laugh. Earthquakes are common in Japan—that one
was the third of the week—and the participants were, after all, at a seismology
conference. Then everyone in the room checked the time.
Seismologists know that how long an
earthquake lasts is a decent proxy for its magnitude. The 1989 earthquake in
Loma Prieta, California, which killed sixty-three people and caused six billion
dollars worth of damage, lasted about fifteen seconds and had a magnitude of
6.9. A thirty-second earthquake generally has a magnitude in the mid-sevens. A
minute-long quake is in the high sevens, a two-minute quake has entered the
eights, and a three-minute quake is in the high eights. By four minutes, an
earthquake has hit magnitude 9.0.
When Goldfinger looked at his watch, it was
quarter to three. The conference was wrapping up for the day. He was thinking
about sushi. The speaker at the lectern was wondering if he should carry on
with his talk. The earthquake was not particularly strong. Then it ticked past
the sixty-second mark, making it longer than the others that week. The shaking
intensified. The seats in the conference room were small plastic desks with
wheels. Goldfinger, who is tall and solidly built, thought, No way am I
crouching under one of those for cover. At a minute and a half, everyone in the
room got up and went outside.
It was March. There was a chill in the air,
and snow flurries, but no snow on the ground. Nor, from the feel of it, was
there ground on the ground. The earth snapped and popped and rippled. It was,
Goldfinger thought, like driving through rocky terrain in a vehicle with no
shocks, if both the vehicle and the terrain were also on a raft in high seas.
The quake passed the two-minute mark. The trees, still hung with the previous
autumn’s dead leaves, were making a strange rattling sound. The flagpole atop
the building he and his colleagues had just vacated was whipping through an arc
of forty degrees. The building itself was base-isolated, a seismic-safety
technology in which the body of a structure rests on movable bearings rather
than directly on its foundation. Goldfinger lurched over to take a look. The
base was lurching, too, back and forth a foot at a time, digging a trench in
the yard. He thought better of it, and lurched away. His watch swept past the
three-minute mark and kept going.
Oh, shit, Goldfinger thought, although not in
dread, at first: in amazement. For decades, seismologists had believed that
Japan could not experience an earthquake stronger than magnitude 8.4. In 2005,
however, at a conference in Hokudan, a Japanese geologist named Yasutaka Ikeda
had argued that the nation should expect a magnitude 9.0 in the near
future—with catastrophic consequences, because Japan’s famous
earthquake-and-tsunami preparedness, including the height of its sea walls, was
based on incorrect science. The presentation was met with polite applause and
thereafter largely ignored. Now, Goldfinger realized as the shaking hit the
four-minute mark, the planet was proving the Japanese Cassandra right.
For a moment, that was pretty cool: a
real-time revolution in earthquake science. Almost immediately, though, it
became extremely uncool, because Goldfinger and every other seismologist
standing outside in Kashiwa knew what was coming. One of them pulled out a cell
phone and started streaming videos from the Japanese broadcasting station NHK,
shot by helicopters that had flown out to sea soon after the shaking started.
Thirty minutes after Goldfinger first stepped outside, he watched the tsunami
roll in, in real time, on a two-inch screen.
In the end, the magnitude-9.0 Tohoku
earthquake and subsequent tsunami killed more than eighteen thousand people,
devastated northeast Japan, triggered the meltdown at the Fukushima power
plant, and cost an estimated two hundred and twenty billion dollars. The
shaking earlier in the week turned out to be the foreshocks of the largest
earthquake in the nation’s recorded history. But for Chris Goldfinger, a
paleoseismologist at Oregon State University and one of the world’s leading
experts on a little-known fault line, the main quake was itself a kind of
foreshock: a preview of another earthquake still to come.
Most people in the United States know just
one fault line by name: the San Andreas, which runs nearly the length of
California and is perpetually rumored to be on the verge of unleashing “the big
one.” That rumor is misleading, no matter what the San Andreas ever does. Every
fault line has an upper limit to its potency, determined by its length and
width, and by how far it can slip. For the San Andreas, one of the most
extensively studied and best understood fault lines in the world, that upper
limit is roughly an 8.2—a powerful earthquake, but, because the Richter scale
is logarithmic, only six per cent as strong as the 2011 event in Japan.
VOCABULARY:
Determined :Bertekad
Meltdown :Krisis
Lurched :Meluncur
Particularly :Khususnya
Lectern :Podium
Swept :Menyapu
Recorded :Merekam
Bearing :Bantalan
Foreshock :Kejutan
Perpetually :
Terus Menerus
