Reducing the vulnerability of the built environment dramatically improves resiliency in the face of natural climate and geologic events. This page is intended as a resource to help inspire safer human habitation through the geographic integration of science, engineering, economics and public policy. I highlight newsworthy events and share best practices that improve planning and locational decisions, with the goal of reducing the loss of life and property.
“They’re so content with the
beautiful place where they live, they don’t think anything would happen.”
–Charity Prueher (former resident of Oso, Washington)
We watch the coverage of the Oso landslide rescue and
recovery efforts with a mix of sadness and shock.Sadness for the victims of this tragedy and
their families who have been separated—perhaps forever—from the ones they love;
and shock at the thought of such a horrendous thing happening to us or someone
we know.We respect the power of nature
and the seemingly random way in which events like this transpire in our
lives.“But by the grace of God…” we
think to ourselves.
But, with all due respect to those who lost their lives
or now live without ones they love, there is an important lesson to be learned
from this tragedy.It’s one that is
touched upon, mentioned briefly, but carefully sidestepped in most media
reports because it’s too soon to point fingers.The lesson is that this loss of life may have been prevented.
A story on the tragedy from the Washington Post (March
29, 2014) includes the following report. Please excuse the lengthy quote, but the background is important:
At least 18 people have been confirmed dead (as of the date of the
article), and up to 30 more are likely entombed in a thick gray muck, swallowed
by the land, perhaps never to be seen again....Nearly every adult in this part of Snohomish County, a patchwork of
little towns about 50 miles north of Seattle, knew someone who died or knows
someone close to them. It is a tightknit community of loggers who earn
low-wages in jobs cutting timber, and wealthy people, some of them retirees,
who built dream homes on emerald hills with scenic views of the Cascades, near
a river teeming with steelhead and salmon.
But some are now questioning whether many of the homes should have been
built at all in the valley below a hillside that commonly shifts, sending mud
raining down about once a decade. At least four new homes have been built since
the last major landslide muddied the valley eight years ago.The Snohomish County officials who control
land use permits asserted last week that there was no way of knowing a giant
mudslide would ever happen there.
In fact, the area was primed for just such an extraordinary event,
according to geologist Daniel J. Miller, who twice surveyed the area for local
Native American tribes who rely on the river’s health for fishing and for the
Army Corps of Engineers. He wrote in his 1999 report that the Hazel Landslide,
as the mountain is known, was constantly shifting, experiencing landslides and
would one day suffer “a catastrophic failure.This landslide moves every year when it gets wet, and pieces fall off,”
said Miller, a consultant in Seattle, in a telephone interview Friday....
An ancient glacier is jutting out of the mountain, making its flat
plateau unstable, Miller said. The Stillaguamish River was eroding it from
below. Rows of conifer trees that helped to mitigate erosion by sucking water
through their roots and releasing it into the atmosphere were chopped down by
loggers. Rain fell on the bald spots they left, drenching dirt and sand, making
the mountain even more precarious....
Miller realized his warning was not heeded when he visited the site
following a major landslide in 2006 that did not do nearly as much harm. He
could not believe what he saw.“There was
new construction,” he said. “The sound of hammering competed with the sound of
[destabilized] trees snapping after the mudslide. I can’t believe that someone
wanted to build their home there. It was a very bad idea.”
After a tragedy writ large, disbelief and grief often turn to anger and
a demand for accountability. Already, some engineers have criticized local and
state officials for failing to recognize the dangers of development on the
mountain.David Montgomery, a professor
of geology at the University of Washington, said questions must be asked, but
he is not sure blame is deserved.Predicting mudslides is like forecasting the weather or an earthquake,
he said. The science is not exact.
Montgomery praised Miller, a colleague, because his 1999 prediction
appears prophetic in hindsight. But Miller had no way of knowing when his
prediction would come true, and he did not take the added step of estimating
where debris would flow when the slide happened.A report such as that might have gotten the
attention of policymakers, he said. And then again, it might not have.
Geologists have recorded landslides around Seattle for generations, but
dire warnings about shaky ground in their reports are not always greeted as
good news. It can hurt homebuilding and businesses that generate tax income.
Regardless of who is to blame, Montgomery said, the state and other
stakeholders must do whatever is needed to better understand the geology of its
mountains and hills. “We have to use that information to identify the true
hazard areas and run-out zones,” where the cascading debris is likely to go.
Looking back to the table I shared in an earlier post,
landslides and mudslides are somewhat unique in that there is no way to
adequately construct a home or school that is somehow “resistant” to the
disaster.When the very ground you build
on slips away, there are no options.Similarly,
while earthquake damage from shaking and vibration in surrounding areas can be
mitigated to some extent during construction, the only way to avoid earth movement on
the fault itself is to avoid the fault altogether.
Thus the primary tool to minimize property
damage and injury is to place the structure in an area known (or believed) to
be free from direct impact.Obviously, there was some prior knowledge of problems on
that Washington hillside.But
development continued for a variety of reasons.
The foolish man built his house
upon the sand. The rains came down and the
floods came up, And the house on the sand washed
The wise man built his house
upon a rock.
The rains came down and the
floods came up, And the house on the rock stood
It’s human nature to want what we want.But sometimes an individual’s ability to
determine the best course of action is limited by a lack of understanding
(e.g., we’re not all engineering geologists) or hampered a determination to
ignore the warning signs in order to achieve a goal.The former is understandable (and something
that government and others are stepping-in to help mitigate).Sadly, controlling the latter may never be
possible without some limits on the free use of property.
I’ll defer a discussion of the rights of land owners for
another entry.Instead, allow me a brief
diversion.Let me share an experience my
wife and I had in renting a house.Under
a tight deadline, we were forced to quickly make a decision regarding a home
that seemed to be exactly what we wanted.We noted, however, a definite musty smell in the basement—something unexpected
since the house was almost newly built.Upon further investigation, I noted a faint linear deposit of silt,
horizontally along the wall and a matching line of rust on the outside of the
gas furnace housing.Shockingly, the
line was at least 3 feet from the floor.
After pressing the landlord for an answer, we discovered
that the new house had stood vacant for most of the winter months and, as pipes
tend to do when cold, one of them had burst and filled the basement like a
shallow swimming pool.Everything had been
drained and dried, and the internal mechanics of the furnace had been replaced,
but the residual evidence remained.I
confirmed the landlord’s story with the utility company and consulted an
engineer.Knowing that the problem wasn’t
external to the house, we were able to negotiate a lease and enjoy living there.
Seeking and Listening to Expertise
I mention this as an example of how a little initiative
on the part of a potential buyer or builder can, perhaps, avoid serious
problems.But suppose you are renting an
apartment in a large (established) building or, as was apparently the case in
Washington, you are interested in building in an area that has received mixed
reviews in terms of its relative safety.This is where third parties must be prepared to step-in and apply
appropriate restrictions and safeguards to protect both those that don’t know
and those that choose to ignore.
Scott Burns, a professor of engineering geology in Oregon
shares some of the ways this technical expertise can be used in an article cited here.He says:
"The impact of a site evaluation is felt in many ways. It
might result in a change of the design of a structure because of a poor soil —
for example, putting down stabilizing soil atop poor soils (such as expansive
clays) before constructing a house — or a geological hazard, such as building a
house off of the ground in a tsunami zone. Site evaluations might also lead to
setting the structure back from a hazard zone, such as an active fault or at
the top of a landslide. Or we could recommend somewhat simpler solutions such
as grading soils of a steep site where slope stability is a problem, or
building drains where groundwater flow is substantial on a slope. Or, of
course, site evaluations could end up in complete rejection of the site because
of weak soils or bedrock, or other problems with a hazard that would threaten
the safety of humans and property."
The key here is that those seeking the advice of an
expert must heed that advice and not seek ways around it.Some hazards just cannot be avoided.
Third Party Restrictions
I mentioned in an earlier post an Executive Order in
Maryland that requires certain hardening of structures against sea level rise
and coastal hazards.But this only
applies to State buildings.When a
private developer or homeowner wishes to build, there are essentially two ways
that a governmental agency (or private entity with an interest in the
development, like an insurance company or a lender) can help minimize risk: (1)
legal restrictions on use and/or (2) financial incentives/disincentives applied
to the builder or owner.
Legal Restrictions.Many governmental entities include risk maps and restrictions in their
zoning ordinances.Numerous examples are
readily available via the Internet.Here’s just one example from Wasatch County, Utah
Like this example, most cities and counties ask land
owners and developers to seek expert advice if they wish to build in areas
designated as potentially hazardous.What
they do with that information and how strongly an ordinance can restrict
development vary widely among examples.Even more frustrating, restrictions are sometimes eased or modified for
reasons other than safety—for political or economic gain, for instance.
In one California case, engineers sought to mitigate any
potential problems with buttresses and retaining walls that failed.Fingers pointed while the development crumbled
and slid down the hillside.
A more recent Florida example raises a troubling trend.Prompted by pressure from developers and
general confusion over competing policies from various political jurisdictions,
one county reduced by 90% the size of the “high hazard” coastal areas where
development could be restricted.
The ramifications of such decisions are far-reaching and
have financial and life safety implications that go well beyond the region or
the State.The regional impact of Hurricane
Katrina, for instance, reverberated for years through the US economy.
If for some reason you are able to get a building permit
and you build in a hazardous area, you can expect to pay more for property
insurance premiums, assuming you can be insured at all.On the surface this may appear as a way of
putting the burden on the owner for their poor judgment.But the cost of any claims is rarely borne
solely by the owner.The costs are
spread over the entire group of insureds, thereby affecting the pocketbooks of those
that may have chosen more wisely.
Furthermore, some insurance programs may actually be a
disincentive to wise decision-making.The National Flood Insurance Program has been described by some as just
such a counterproductive program.This article by Gilbert Gaul and Anthony Woods from the Philadelphia Inquirer
is eye opening because they describe a taxpayer-subsidized program that
encourages the building and rebuilding of private structures in some of the
most hazardous areas of the country by providing a continuing stream of funding
to insureds for premiums far less than they would have to pay to a private
insurance company.The sheer fact that
insurance companies won’t insure against flood should be sufficient evidence
that this once well-meaning program should be reevaluated.
Seeking an answer
You can’t build a landslide-resistant house or one that
will survive a trip down a mountainside.Obviously something must be done to prevent the loss of life and
destruction of property we have seen in what many have termed “preventable”
disasters.Getting to a safer
development model in the US and in the world, will require a balanced approach encompassing
enhanced personal responsibility, a strengthening of enforceable third-party
restrictions, and more equitable financial incentives that put pressure on
those that benefit most from insurance programs in a way that discourages risky