The Owen's Valley Earthquake, Part II [pp. 266-278]

THE OWEN'S VIALLEY EAR4THQUAKE.
the direction of the. Sierra, in all cases,
and evidently by sound - waves borne
through the atmosphere and not through
the earth. The detrital mass which fills
the bottom of the valley and extends
high up on the flanks of the Sierra, is
made up of loose fragments of rock, of
all sizes, mixed with gravel and sand,
and would seem to be a material eminently ill-fitted for the propagation of
the waves of sound. These must have
emerged into the atmosphere, high up
in the mountains, where the rock is bare
of detritus, and have thence been borne
to the ear through the air.
Having thus given some of the general scientific conclusions which we have
felt justified in drawing from our observations in Owen's Valley, we will append a few words of practical application-a branch of the subject to which
we expect to be able to revert at some
future time.
That there ever can be any hope of
our being able to predict the time of occurrence of an earthquake shock, is in
the highest degree improbable. Seismic
disturbances do not belong to a class of
phenomena of which we can ever expect to know much in detail. We can
say that such and such regions are more
liable to be visited by these catastrophes
than others are; but when they will
happen, there is no possibility of ascertaining in advance. Neither are the various warnings supposed to be given by
peculiar meteorological occurrences of
any value. There is a slight preponderance in the number of shocks occurring
in winter, over that of the summer disturbances, and it is quite probable that
the moon is not without some influence
on the movements of the crust of our
planet; but neither of these circumstances affords any basis for prediction.
If the evils of earthquakes can in any
way be mitigated, it is in preparing for
them by building in a suitable manner.
It was the opinion of Mr. Mallet, formed
with much deliberation, after his elaborate investigation of the Neapolitan
earthquake, that most of the horrors of
these catastrophes might be averted by
proper care in the construction of houses
and public buildings. This opinion is
of great value, because this able investigator had the most excellent opportunities of studying the effects of movements
of the crust on edifices of a great variety
of form and material.
The results of the Owen's Valley
earthquake are not without considerable value in this respect. The fact that
wooden buildings are superior to all others, for regions liable to severe shocks,
seems clearly established, at least in
cases where the edifice is to be one of
moderate cost and size. We would not
be taken as positively asserting that a
building of brick or stone may not be
made as safe as one of wood; but it is
clear that it can not be without a very
much larger expenditure of money. Of
all the materials which can be used for
building purposes the adobe is most unsafe. The walls built of this material
have the least possible cohesion and elasticity. However convenient the adobe
may be, in certain localities, where wood
is dear, and protection from cold wind
and hot sun much to be desired, it should
not be used anywhere on this coast.
Where brick buildings are absolutely
necessary, as in the large cities, they
should be constructed in the most substantial manner, with special regard to
the quality of the mortar, and well tied together with iron rods. The use of heavy
cornices and massive chimneys should
be entirely abandoned. In all the brick
buildings overthrown or badly injured
by the shock of March 26th, the bad
quality of the mortar was most distinctly
noticeable. That of the court - house at
Independence, which was almost destroyed by the earthquake, had no more
coherence than so much dried mud.
Finally, the desirability of a scientific
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