Quakeland: On the Road to America’s Next Devastating Earthquake
Roger Bilham
Given
recent seismic activity — political as well as geological — it’s
perhaps unsurprising that two books on earthquakes have arrived this
season. One is as elegant as the score of a Beethoven symphony; the
other resembles a diary of conversations overheard during a rock
concert. Both are interesting, and both relate recent history to a shaky
future.
Journalist
Kathryn Miles’s Quakeland is a litany of bad things that happen when
you provoke Earth to release its invisible but ubiquitous store of
seismic-strain energy, either by removing fluids (oil, water, gas) or by
adding them in copious quantities (when extracting shale gas in
hydraulic fracturing, also known as fracking, or when injecting
contaminated water or building reservoirs). To complete the picture, she
describes at length the bad things that happen during unprovoked
natural earthquakes. As its subtitle hints, the book takes the form of a
road trip to visit seismic disasters both past and potential, and
seismologists and earthquake engineers who have first-hand knowledge of
them. Their colourful personalities, opinions and prejudices tell a
story of scientific discovery and engineering remedy.
Miles
poses some important societal questions. Aside from human intervention
potentially triggering a really damaging earthquake, what is it actually
like to live in neighbourhoods jolted daily by magnitude 1–3
earthquakes, or the occasional magnitude 5? Are these bumps in the night
acceptable? And how can industries that perturb the highly stressed
rocks beneath our feet deny obvious cause and effect? In 2015, the
Oklahoma Geological Survey conceded that a quadrupling of the rate of
magnitude-3 or more earthquakes in recent years, coinciding with a rise
in fracking, was unlikely to represent a natural process. Miles does not
take sides, but it’s difficult for the reader not to.
She
visits New York City, marvelling at subway tunnels and unreinforced
masonry almost certainly scheduled for destruction by the next moderate
earthquake in the vicinity. She considers the perils of nuclear-waste
storage in Nevada and Texas, and ponders the risks to Idaho miners of
rock bursts — spontaneous fracture of the working face when the
restraints of many million years of confinement are mined away. She
contemplates the ups and downs of the Yellowstone Caldera — North
America’s very own mid-continent supervolcano — and its magnificently
uncertain future. Miles also touches on geothermal power plants in
southern California’s Salton Sea and elsewhere; the vast US network of
crumbling bridges, dams and oil-storage farms; and the magnitude 7–9
earthquakes that could hit California and the Cascadia coastline of
Oregon and Washington state this century. Amid all this doom, a new
elementary school on the coast near Westport, Washington, vulnerable to
inbound tsunamis, is offered as a note of optimism. With foresight and
much persuasion from its head teacher, it was engineered to become an
elevated safe haven.
Miles
briefly discusses earthquake prediction and the perils of getting it
wrong (embarrassment in New Madrid, Missouri, where a quake was
predicted but never materialized; prison in L’Aquila, Italy, where
scientists failed to foresee a devastating seismic event) and the
successes of early-warning systems, with which electronic alerts can be
issued ahead of damaging seismic waves. Yes, it’s a lot to digest, but
most of the book obeys the laws of physics, and it is a engaging read.
One just can’t help wishing that Miles’s road trips had taken her
somewhere that wasn’t a disaster waiting to happen.
Catastrophic damage in Anchorage, Alaska, in 1964, caused by the second-largest earthquake in the global instrumental record.
In
The Great Quake, journalist Henry Fountain provides us with a
forthright and timely reminder of the startling historical consequences
of North America’s largest known earthquake, which more than half a
century ago devastated southern Alaska. With its epicentre in Prince
William Sound, the 1964 quake reached magnitude 9.2, the second largest
in the global instrumental record. It released more energy than either
the 2004 Sumatra–Andaman earthquake or the 2011 Tohoku earthquake off
Japan; and it generated almost as many pages of scientific commentary
and description as aftershocks. Yet it has been forgotten by many.
The
quake was scientifically important because it occurred at a time when
plate tectonics was in transition from hypothesis to theory. Fountain
expertly traces the theory’s historical development, and how the Alaska
earthquake was pivotal in nailing down one of the most important
predictions. The earthquake caused a fjordland region larger than
England to subside, and a similarly huge region of islands offshore to
rise by many metres; but its scientific implications were not obvious at
the time. Eminent seismologists thought that a vertical fault had
slipped, drowning forests and coastlines to its north and raising
beaches and islands to its south. But this kind of fault should have
reached the surface, and extended deep into Earth’s mantle. There was no
geological evidence of a monster surface fault separating these two
regions, nor any evidence for excessively deep aftershocks. The
landslides and liquefied soils that collapsed houses, and the tsunami
that severely damaged ports and infrastructure, offered no clues to the
cause.
“Previous
earthquakes provide clear guidance about present-day vulnerability.”
The hero of The Great Quake is the geologist George Plafker, who
painstakingly mapped the height reached by barnacles lifted out of the
intertidal zone along shorelines raised by the earthquake, and
documented the depths of drowned forests. He deduced that the region of
subsidence was the surface manifestation of previously compressed rocks
springing apart, driving parts of Alaska up and southwards over the
Pacific Plate. His finding confirmed a prediction of plate tectonics,
that the leading edge of the Pacific Plate plunged beneath the southern
edge of Alaska along a gently dipping thrust fault. That observation,
once fully appreciated, was applauded by the geophysics community.
Fountain
tells this story through the testimony of survivors, engineers and
scientists, interweaving it with the fascinating history of Alaska, from
early discovery by Europeans to purchase from Russia by the United
States in 1867, and its recent development. Were the quake to occur now,
it is not difficult to envisage that with increased infrastructure and
larger populations, the death toll and price tag would be two orders of
magnitude larger than the 139 fatalities and US$300-million economic
cost recorded in 1964.
What is clear from these two books is
that seismicity on the North American continent is guaranteed to
deliver surprises, along with unprecedented economic and human losses.
Previous earthquakes provide clear guidance about the present-day
vulnerability of US infrastructure and populations. Engineers and
seismologists know how to mitigate the effects of future earthquakes
(and, in mid-continent, would advise against the reckless injection of
waste fluids known to trigger earthquakes). It is merely a matter of
persuading city planners and politicians that if they are tempted to
ignore the certainty of the continent’s seismic past, they should err on
the side of caution when considering its seismic future.
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