[Greenbuilding] Earthquakes and older houses
Bob Waldrop
bwaldrop1952 at att.net
Wed Mar 30 15:02:55 CDT 2016
PS. I forgot to mention that it looks to us like our foundation is
brick all the way down, with a large timber, like a railroad tie,
sitting on top of it, with the rest of the house resting on that
timber. I do agree with one of the commenters that our main concern is
more surviving the actual event, and less preserving the building. Even
with a 10% deductible, we'll have enough insurance money to build
something and replace the contents. So I am more interested in figuring
out how to avoid the pancake scenario where the ceiling and walls
pancake down on us occupants. One of my roomies said "Maybe we should
build canopy beds that would be strong enough to hold up the roof."
Someone mentioned liability of frackers, there are a few cases wending
their way through the courts. It's interesting because they are setting
up a clash of titans -- Oklahoma Oil Bidness verses the Oklahoma
Insurance Bidness. Everyone is generally amazed that the Corporation
commission has actually moved as fast as it has to curb produced water
injection well which people seem to think are the primary cause. The
further north you go in the OKC metro area, the more upscale the
neighborhoods, and the most upscale neighborhoods are squarely within
the heightened danger zone. And also folks are amazed at how obedient
the oil companies have been. Only one company balked, and the
legislature rammed through a bill this session with great haste
confirming that the corporation commission does in fact have the
authority to dictate injection pressures and volumes if earthquakes are
happening in the area.
So basically there's a giant science experiment going on -- "how much
water can be injected at what pressures without causing a devastating
earthquake or too many minor earthquakes."
rmw
On 3/30/2016 2:52 PM, Bob Waldrop wrote:
> Thanks everyone for these detailed comments and suggestions. There's a
> lot to take in, I'm printing the emails and will share them around a
> bit and see about coming up with a plan of action. One "low hanging
> fruit" item we're taking care of this week is making sure that nothing
> furnishing-like can fall on us while in bed or casually sitting
> around. This involves re-siting some large mirrors, paintings, and
> book cases.
>
> Bob Waldrop, Okie City
>
> On 3/30/2016 8:32 AM, Alan Abrams wrote:
>> Bob--
>>
>> imagining the Oklahoma version of "The Big One," I think the gravest
>> danger is the collapse of the brick foundation walls. in our
>> region,bricks from the 20's can be pretty soft, and the mortar can be
>> powdery.
>>
>> if that all describes the scenario, simply anchoring the floor system
>> to the top of the brick walls might be inadequate. the strength of
>> the foundation walls would be limited to the compressive force
>> exerted by the weight of the house above. in this sense, the weight
>> of the brick veneer is your friend--but I think the veneer is going
>> to be the first element to fail when things start to shake. The point
>> being, that even if the floor is anchored, the foundation walls could
>> rotate in, between corners.
>>
>> one could of course jack up the house and install a new reinforced
>> cmu or poured concrete foundation beneath it. Or form up and pour new
>> walls against the existing walls.
>>
>> but less intrusively, one might strengthen the walls by increasing
>> the compressive force--perhaps by excavating and installing a set of
>> pier footings at intervals around the basement perimeter, each pier
>> footing undermining the existing footing--maybe 2' wide or so. each
>> pier would have a reinforced anchor bolt, to fasten some set of
>> threaded rods and turnbuckles--which in turn would be bolted to the
>> floor joists. Ideally, there would be two rods for each pier footing,
>> run diagonally in opposite directions, parallel to the foundation walls.
>>
>> There a lot of boggling variables here--such as the moisture content
>> and plasticity of the soil, height of backfill, direction of seismic
>> waves--so sizing the footings and rods, and determining how many to
>> install would be speculative. Maybe a big shaker would overcome this
>> effort. Or maybe it would hold up long enough for you to escape
>> before it all comes down. I don't envy your situation.
>>
>> -aa
>>
>>
>>
>> Alan Abrams*
>> */certified professional building designer, AIBD
>> certified passive house consultant, PHIUS/
>> /certified passive house builder, PHIUS//
>> /cell 202-437-8583
>> alan at abramsdesignbuild.com <mailto:alan at abramsdesignbuild.com>
>> HELICON WORKS /Architecture and Education/
>> <http://www.heliconworks.com/index2.html>
>>
>> On Tue, Mar 29, 2016 at 11:05 PM, ErgoDesk <ergodesk at gmail.com
>> <mailto:ergodesk at gmail.com>> wrote:
>>
>> California... I would reinforce your FIRE Insurance first.
>>
>> Sincerely,
>> George Hawirko_
>> _
>> _http://about.me/StyroHome_
>>
>>
>> On Tue, Mar 29, 2016 at 11:40 AM, Jason Holstine
>> <jason at amicusgreen.com> wrote:
>>
>>
>> I think you can find retrofit resources online from
>> California. I think their state emergency mgmt agency, state
>> NAHB, etc. have docs. It could become a nice side biz
>> tightening up Okie corrals.
>>
>>
>>
>> On 3/29/16 1:41 PM, "Bob Waldrop" <bwaldrop1952 at att.net> wrote:
>>
>> > So here in central Oklahoma, we have been experiencing a growing series
>> > of earthquakes over the last few years. The USGS just
>> released a map
>> > showing the risk of human-induced earthquakes, and Okie
>> City is right
>> > there. The news said we were at perhaps a 10% risk of a
>> level 6
>> > earthquake. Most of the thus far have been in the 2 to 4
>> range.
>> >
>> > Now we are not only tornado alley, but also earthquake
>> central, more
>> > earthquakes last year even than California had.
>> >
>> > I lived in the Bay Area of California and in SLC (on top of
>> the actual
>> > wasatch fault a geologist friend told me), and never
>> experienced a
>> > quake, but I've felt several here. I've also been watching
>> the cracks
>> > in the interior plaster/lathe walls and my exterior brick
>> veneer develop
>> > and progress.
>> >
>> > I do have earthquake insurance, but it is really only good
>> for a
>> > complete catastrophe. It has a 10% deductible, and it
>> doesn't cover
>> > masonry.
>> >
>> > The house has always seemed very sturdy. It was built in
>> 1929, the
>> > studs are on 12 to 14 inch centers and are a hard wood.
>> THe sheathing
>> > is 1 x 8 planks. Then there is brick veneer over that. The
>> foundation
>> > is brick. The back and front porch construction seems
>> separate from the
>> > rest of the house. The concrete front porch is certainly
>> pulling away
>> > from the rest of the house over the 16 years I've lived here.
>> >
>> > Any thoughts about retrofits that would strengthen the
>> house in the face
>> > of the growing earthquake risk here?
>> >
>> > Bob Waldrop, Okie and Shaky City
>> >
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