NATURE'S WARNING OF COMING EARTHQUAKES
That there are signs of coming earthquakes which might be read by
man, had he sufficient knowledge, there would seem to be but little
doubt. These phenomena follow natural laws so that the approach of an
earthquake must necessarily be in a definite order both as regards
the phenomena which precede as well as those which follow it. There
should, therefore, be signs that would enable one to predict its
coming, although it must be acknowledged that these signs, so far as
we actually know, are indistinct.
It may seem to the unthinking and unobservant that the awful
catastrophe of an earthquake comes entirely unheralded; that,
apparently, it is not until the earth's surface begins to rock to
and fro under the mighty forces that are causing destruction that
its presence can be known. There are, however, many reasons for
believing that in, perhaps, the greatest number of cases, it might
have been foreseen, if greater attention had been given to the
slight indications of its probable approach a short time before its
occurrence.
It is evident that the conditions of great pressure or stress in the
earth's crust which finally result in a disastrous earthquake have
been slowly accumulating for a long time, and that when the pressure
at last reaches a point where the crust has to yield or slip, the
ground is suddenly crushed and tossed to and fro while vast fissures
and chasms are produced in the subterranean regions. At those points
of the earth immediately above or in the neighborhood of such regions
it is possible that there are many signs of the coming quake;
and, although indistinguishable by our duller senses, are readily
appreciated by the more highly developed senses of the lower animals.
Indeed, had we accustomed ourselves to reading the various indications
of nature as the lower animals have, we, too, might be able to read
these warnings of the coming earthquake.
At great distances from the place where the earthquake starts there
would necessarily be a better opportunity for predicting its approach.
As already stated, what is called an earthquake does not consist
of a single shaking of the ground, but of a highly complex series
of shakings. According to Mallet, the following waves start at the
same time from the place of origin of an earthquake, when located
on the bed of an ocean; i. e., an earth sound wave and a earth wave
constituting the earth's shake; a sound wave through the ocean,
another through the air; a sea wave called by him a forced sea wave,
and finally the great sea wave.
These waves reach a distant point in the following order: the sound
wave through the earth and the great earthquake or shake which
produces the damage. Then a smaller sea wave called the forced sea
wave. This is followed almost immediately by the sound wave through
the sea. Next come the air sound wave and finally the great sea wave;
which, rushing in on the shore, sweeps nearly everything before it.
In other words, the disturbances produced by the great earthquake
follow in this order of sequence. If, therefore, the great earthquake
wave proper transmitted through the earth should for any reason be
delayed in reaching a distant place, the great sound waves should be
able to give warning of the coming disturbances.
Again, as we have already seen, the earthquake wave is preceded by a
number of preliminary tremors, and is followed by a number of after
tremors or _earthquake echoes_. Since, therefore, the preliminary
waves reach a place first, it would seem that the approach of an
earthquake must be heralded by the preliminary tremors. These,
perhaps, at least in part, enable the lower animals to detect its
coming.
Again, in almost all instances there are a number of preliminary
shocks that precede the great earthquake shock. Some of these
preliminary shocks continue at intervals for several days or even
longer. Sometimes, indeed, these subterranean sounds fail to be
followed by earthquakes. Milne thinks that these sounds are caused
by the preliminary tremors which precede the principal shock of the
earthquake and that they reach the place first. Here again then it
is evident that, were we able to interpret properly these sounds, we
would probably be able to foretell the coming quake with a fair degree
of certainty.
There would appear to be no reasonable doubt that in some manner
which we have not yet been able to discover, but probably along some
of the lines indicated above, animals are capable of recognizing a
coming earthquake. Long before the coming of the catastrophe they are
said to exhibit extreme terror, and in many cases appear to seek the
companionship of man, as if for protection.
That the senses of smell and hearing are far more acute in the lower
animals than in man no one can reasonably doubt. The manner in which
a trained dog can follow a scent, for a long time after the animal
or thing producing it has passed, far exceeds the power of scent
possessed by man, and it is more than likely that this same power is
possessed by all animals who live upon or prey upon other animals. It
is probable that faintly odorous vapors or gases escape from the crust
shortly before the great shock occurs, and that these faint odors are
warnings to the animals of the approaching calamity. The sense of
hearing also is much more acute in the lower animals.
Daubeny is evidently of this belief, as will be seen from the
following:
"These gases and vapors (alluding to emanations given off
from the ground during earthquakes) exert an influence
on the barometer, which does appear to be indirectly
affected by the earthquake. Then, similar properties
also may occasion that uneasiness which animals are said
to evince before any such event. Thus, according to the
accounts of some writers, rats and mice leave their holes,
alligators seek the dry land, quadrupeds snuff the ground,
and manifest such signs of the impending calamity that in
countries where earthquakes are common, the inhabitants
take the alarm in consequence, and escape from their
houses. It is right, however, to add, that more recent
authorities dispute altogether the correctness of these
statements."
Dutton doubts the ability of animals to foretell coming earthquake
shocks.
But that the lower animals do exhibit signs of fear at the approach of
an earthquake has been repeatedly asserted by good observers.
Hamilton, who made a careful examination of the neighboring country
during the great earthquake at Calabria, asserts that horses and oxen
during the shocks extended their legs widely in order to avoid being
thrown down, "and that hogs, oxen, horses, and mules, and also geese,
appeared to be painfully aware of the approach of the earthquake of
Calabria; and the neighing of a horse, the braying of an ass, or the
cackling of a goose, even when he (Hamilton) was making his survey
(after the occurrence of the great earthquake shock), drove the people
out of their temporary sheds in expectation of a shock."
It is asserted that birds appear to be especially sensible to a coming
earthquake shock. That geese will quit the water in which they were
swimming before the earthquake and will not return to it. It is quite
possible that these birds with their heads immersed in the water can
hear the distant murmurings long before they become audible in the air.
Von Hoff makes the following statement:
"It has been remarked that at such times (immediately
before the coming of an earthquake shock), domestic animals
showed a decided uneasiness, dogs howled mournfully, horses
neighed in an unusual manner, and poultry flew restlessly
about. These latter phenomena might easily be produced by
mephitic vapours, which often ascend to the surface of the
earth before the breaking out of an earthquake."
Mallet states that there is abundant evidence that earthquake shocks,
even when not of very great intensity, produce nausea in both men and
women. This would seem natural, since, as everyone knows, until one
is accustomed to sea-voyages, merely to be tossed to and fro by the
motion of the waves results in the production of sea-sickness.
It has been also noticed that during earthquakes fish which under
ordinary circumstances live in the mud at the bottom of bodies of
water come near to the surface and at such times can be caught in
great numbers.
Mallet cites the following effects produced by earthquakes:
"Amongst the effects supposed to be produced by the
earthquake on the atmosphere were reckoned tempestuous
winds, thunder-storms, meteors, coldness of the air,
severe winters, heavy rains, miasmata, producing diseases
and affecting vegetation. A very remarkable instance of
the latter is quoted, namely, that in Peru, after the
earthquake of 1687, wheat and barley would not thrive at
all, though formerly the country was remarkably favourable
for them."
Sir Charles Lyell notes the following phenomena attending earthquakes:
"Irregularities in the seasons preceding or following the
shocks; sudden gusts of wind, interrupted by dead calms;
violent rains at unusual seasons, or in countries where,
as a rule, they are almost unknown; a reddening of the
sun's disk, and haziness in the air, often continued for
months; an evolution of electric matter, or of inflammable
gas from the soil, with sulphurous and mephitic vapours;
noises underground, like the running of carriages, or
the discharge of artillery, or distant thunder; animals
uttering cries of distress, and evincing extraordinary
alarm, being more sensitive than men to the slightest
movement; a sensation like sea-sickness, and a dizziness in
the head, experienced by men. These, and other phenomena,
less connected with our present subject as geologists, have
recurred again and again at distant ages, and in all parts
of the globe."
THE END
FOOTNOTES:
[Footnote 1: A point on the other side of the earth directly opposite
a given point.]
[Footnote 2: A fracture of a stratum, or a general rock mass, with a
relative displacement of the opposite sides of the break.
The plane or fracture of a fault, known as the fault-plane, is seldom
vertical. The higher side is called the heaved or upthrow side; the
opposite side the thrown or downthrow side.]
[Footnote 3: _Tectonic Earthquake_. An earthquake due to the sudden
slip of faulted strata.]
[Footnote 4: _I. e._, burnt out mountain, extinct volcano.]
[Footnote 5: _Epicentre._ A point on the surface of the earth
vertically above the point of origin of an earthquake, or the place
where it starts.]
Transcriber's Notes
Obvious printer errors have been silently corrected.
Some illustrations have been moved to paragraph breaks.
Page 43: Kamehamoha could be a typo for Kamehameha.
Page 68: Changed "salter" to "saltier."
(Orig: another with water salter than the sea,)
Page 76: Changed "Ena" to "Etna."
(Orig: during his time Mt. Ena had lost so much of its height)
Page 115: "eruption during the winter of 1841-43," could be a typo for
1841-42 or 1842-43.
Page 122: "Mont Pelée" could be a typo for "Mount Pelée."
Page 136: 43° C." (109° 4' F.). could be a typo for (109.4° F.).
Page 341: Changed one-eight to one-eighth.
(Orig: It was equal to one-eight of a Roman mile)
Retained the following spelling variations:
Page 49: The largest volcano in Iceland, the Dyngjufköll,
Page 57: The largest volcano in Iceland is Dyngjufjoll.
Pages 52, 193, 311: Geikie
Page 181: Geicke
Pages 17, 156, 257: Hindostan
Page 165: Hindustan
Page 63: Lucullis
Page 76: Lucullus