THE MEDITERRANEAN NATURALIST 
349 
craters, due to the contraction of the crust from 
the heat generated by the rapidly rising lava, 
constitute a purely superficial seismic wave pro- 
pagated into the surrounding region upon its 
surface, and barely extending beyond a few miles 
from its point of origin. This is especially noti- 
ceable with Vesuvius, Etna, and the volcanoes 
of Japan. As an example we have only to take 
the great eruption of the Bandai— san volcano in 
Japan on July 15th 1888 which was attended 
with such serious loss of life. 
Although the effects of this eruption were ter- 
rific and the earthquake shocks of great intensity 
the shaken area was limited to a radius of 25 miles 
beyond which nothing was felt. In moderately 
strong shocks occurring in non-volcanic zones the 
radius is rarely less than 100 miles. Again vol- 
canic earthquake shocks are more frequently 
vertical than undulating, where as non — volcanic 
ones are in an inverse ratio. The former have no 
fixed periods of occurrence nor do any shocks occur 
unless an eruption is imminent the latter however 
have a law which governs the periodical visits of 
of the very violent shocks and small ones are 
continually felt even during the so called period 
of quiescence. The earthquakes which precede an 
eruption may almost be said to accompany it. In 
the Bandai — san case, the first shock occurred 
at 7. 10 a.m. a more violent one at 7. 30 lasting 20 
seconds and a third still more violent a few 
minutes afterwards which lasted 70 seconds and 
was immediately followed by the bursting open 
with terrific force of this assumedly extinct volca- 
no the last previous explosion of which had taken 
place over 1000 years before. Now from all the 
records and traditions of disastrous earthquakes 
in non-Volcanic centres warning shocks take place 
at least two months— frequently more but never 
less — before the great one happens. These shocks 
are of daily occurrence and of varying force, except 
just before the big quake when there is invariably 
a period of absolute quiescence. When this big 
shock do 'S take place it is followed by an immense 
number >f others, often very strong but never 
stronger than the first, and eventually these die 
ou t and the several districts return to their normal 
condition of periodical small disturbances many 
other examples could be given to prove the 
existence of these two distinct clasess of earth- 
quakes but space will not permit their conside- 
ration, at least in this paper. 
In attempting to establish a theory as to the 
real cause of non-volcanic earthquakes particular 
attention must be given to actual facts, confirmed 
details and some logically substantiated support 
of the assumed deductions which have been ar- 
rived at. To talk of the existence of molten “lava 
streams” moving under the upper-crust of the 
“earth” the “ interconnection between volcanoes 
and far off earthquake centres;” “the influence of 
the moon in certain phases; sunspots and meteo- 
rological anomalies” simply bewilders the student 
and diverts the research into false channels. We 
accepted Laplace’s theory of central fire in lieu of a 
better; and we believed our world to have been 
constructed from the same in its process of cooling; 
but today we find every thing tending to disprove 
this and to attribute our planet’s existence to 
Light alone. “God said Let, there, be Light and 
there • was Light ” and hence our planet. To as- 
sume that volcanoes are the vent-holes of the 
plausibly doctrinal hypothesis of central fire is as 
irrational as asserting that thermal springs also 
originate in the bowels of the earth instead of 
near its surface, and to pretend that the sun, moon, 
or atmosphere could possibly cause one microsco- 
pical spot of the whole globe to rock and sway as 
Zante has recently done is pure nonsense, and as 
inadmissable as if we assumed earthquakes to’ 
originate supernaturally. 
That all seismic disturbances originate on the 
surface of the earth or but a few feet below it 
must be admitted when the whole question has 
been thoroughly considered. 
Were it otherwise the range of destructive mo- 
tion-acceleration would be enormous and not 
confined to a score of miles or so. 
Of non-volcanic earthquakes 90 % at least ori- 
ginate in the sea and the remainder by subsidence, 
erosion by underground rivers, and the chemical 
action of an anomolous subsoil &c. Who ever 
thinks of attributing the great Lisbon earth- 
quake to anything else than an immense subsi- 
dence due to a honeycombed foundation — which 
to judge from the anomalies of the sea’s bottom* 
the currents of the river Tagus, and many other 
attendant phenomena — constitute still a standing 
I menace to that great city. At Casamicciola we 
