Earthquake Facts:
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K2: What magnitude earthquake would my house withstand if it is
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designed under the International Building Code (IBC)?
This is a great question and a tough one for engineers to answer. The simple
answer is, “Well, it depends...” It’s kind of like asking a doctor “How long will
I live?” or “Will I ever get sick?” There are so many variables and factors to
consider that the rest of my simple answer has to be, “…let me explain.”
The IBC requires that a structure must be able to withstand 2/3 of the force
of an earthquake with a 2 percent chance of occurring in fifty years. But
there are several ways to measure an earthquake and several ways the
energy released from an earthquake will affect a structure. Engineers no
longer use the original Richter scale for measuring an earthquake, but an
updated version called "Magnitude X.0'' (listen for the TV reporters to be
specific). A magnitude 6.0 earthquake releases 32 times more energy than
a magnitude 5.0 and nearly 1,000 times more energy than a 4.0. But this
does not mean the ground shakes a thousand times harder in a 6.0 than a
4.0 because the energy could be released over a much larger area or the
site-specific geological (soil) conditions may be more conducive for
transferring devastating forces to a structure above.
Engineers are more concerned with how fast the ground is moving (or what
we call the 5-percent damped design spectral response acceleration)
because this allows us to calculate a force. Then based on the height and
weight of the house and the soil conditions under the house we can design
the structure. Now our design does not mean your house will not be
damaged in an earthquake; rather, it means steps have been taken to
minimize catastrophic damage so that the people inside can safely get out.
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USGS reports the
probability of a
magnitude 6.5 or
greater earthquake
occurring in the next
fifty years is between
50 and 60% for the
Reno-Carson CityMinden urban area.
The San Andreas
Fault moves 2 inches
per year. At this rate
Los Angeles and San
Francisco will be next
to each other in 15
million years.
Every year southern
California has over
10,000 earthquakes.
Most of them are
small but at least 20
of them are greater
than magnitude 4.0
From 1975-1995 there
were only four states
that did not receive
any damage caused
by earthquakes:
Florida, Iowa, North
Dakota, and
Wisconsin.
Community Service
K2 is FEMA ATC-20 certified to
perform Postearthquake Building
Safety Evaluations. This means
when an earthquake occurs, K2
will be working with local
jurisdictions to assess damaged
structures and determine which
buildings are lawfully safe to
occupy and which ones are not.
If you have any more questions about earthquakes and how we design for
them, please don’t hesitate to contact either me or Brandt Kennedy at the
contact info below. We provide Earthquake Engineering in-house and
utilize cutting-edge technology to help our designs be the safest and most
economical they can be.
K2
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Your FAST-TRACK to Building Permits ● 2011 August Newsletter ● 3100 Mill St. Suite 107, Reno, NV ● www.K2eng.net ● (775) 355-0505