[Cob] cob and earthquakes

[Kyle Towers]

----- Original Message -----

> I have read and heard about a home in New Zealand, I think there is
> info in The Hand Sculpted House, that was one of the few buildings left
> standing after a major earthquake hit.  I think that the idea behind
> cob is that it is a monolithic building structure and if you have good
> long straw and and enough mass via thick walls firmly attached to a
> foundation, the building stops being bits and pieces of materials and
> really takes on a life of its own.
>
> The tensile and shear strength of something built well seems phenomenal
> to me.

    I've read about that house elsewhere, but caution you about drawing
hasty conclusions.  The tensile and shear strengths of cob have been studied
and are far from phenomenal.  The mass, however, could easily be considered
to be so.  Alas, it is often mass that gets a building in trouble in an
earthquake.  The foundation moves and the massive inertia of the building
causes it to be left behind.  As cob has no significant ductility (unlike
wood, steel, etc.), it breaks.  Also, it is mass that kills.  A little
drywall won't crush you like a 2' thick slab of clay.
    My baloney detector is registering the familiar signature of a 'true
believer'.  Even your autosignature is as slanted as a certain tower in
Italy:

> Although insecticide use in the U.S. increased more than tenfold since
> 1945 to date, crop losses to insects have nearly doubled during this
> period.
>
> - David Pimintell, Ph.D., Cornell University

    What you failed to mention was that yields MORE than doubled.  Your
carefully selected quote was, I assume, to leave the reader with the
impression that, had insecticide use remained at 1949 levels, we would have
lower insect crop losses.  The truth, of course, is that insecticides are,
whether you like it or not, an integral part of that increase.  The data:

1)  "...since 1940, the average annual rate of gain (in U.S. corn yields)
has been about 1.8 bu/ac/yr"  -  W.E. Larson and V.B. Cardwell, University
of Minnesota

2)  Crop yields, bushels per acre:

                  Corn    Soybeans

1950-59         43         21
1960-69         71         25
1970-79         90         28
1980-89        105        30
1990-94        120        36      - www.agcom.purdue.edu/AgCom/news/archives

3)  "We saw that between 1950 and 1981, there was about a 24% increase in
cultivated acreage. However, over that same interval, WORLD grain yields per
ha more than DOUBLED as indicated in Figure 2, below."

"Between 1950 - 1990, grainland productivity (yields per ha) rose more than
2% per year, at least matching and generally exceeding the rate of
population growth."

- World Watch Institute


".The contribution of science is to enlarge beyond all former bounds the
evidence we must take account of before forming our opinions. Today's
opinions may not be the same as yesterday's, because they are based on
fuller or better evidence. We should quite often have occasion to say "I
used to think that once, but now I have come to hold a rather different
opinion." People who never say as much are either ineffectual or
dangerous." - P. Medawar

Kyle Towers