Climatic Changes: Their Nature and CausesHuntington, Ellsworth
Science
Climatic Changes: Their Nature and Causes
Huntington, Ellsworth
Climatic changes; Climatology; Paleoclimatology
In order to test this conclusion in another way we have followed a
suggestion of Professor Schlesinger. Under his advice the Eulerian
motion has been eliminated and a new series of earthquake records has
been compared with the remaining motions of the poles which presumably
arise largely from meteorological causes. For this purpose use has been
made of the very full records of earthquakes published under the
auspices of the International Seismological Commission for the years
1903 to 1908, the only years for which they are available. These include
every known shock of every description which was either recorded by
seismographs or by direct observation in any part of the world. Each
shock is given the same weight, no matter what its violence or how
closely it follows another. The angle of deflection has been measured as
Milne measured it, but since the Eulerian motion is eliminated, our zero
is approximately the normal condition which would prevail if there were
no meteorological complications. Dividing the deflections into six equal
groups according to the size of the angle, we get the result shown in
Table 10.
TABLE 10
EARTHQUAKES IN 1903-1908 COMPARED WITH DEPARTURES OF THE PROJECTED
CURVE OF THE EARTH'S AXIS FROM THE EULERIAN POSITION
_Average angle of deflection_ _Average daily number
(_10 periods of 1/10 year each_) of earthquakes_
-10.5 deg. 8.31
11.5 deg. 8.35
25.8 deg. 8.23
40.2 deg. 8.14
54.7 deg. 8.86
90.3 deg. 11.81
Here where some twenty thousand earthquakes are employed the result
agrees closely with that of Milne for a different series of years and
for a much smaller number of earthquakes. So long as the path of the
pole departs less than about 45 deg. from the smooth gyroscopic Eulerian
path, the number of earthquakes is almost constant, about eight and a
quarter per day. When the angle becomes large, however, the number
increases by nearly 50 per cent. Thus the work of Milne, Knott, and
Jeffreys is confirmed by a new investigation. Apparently earthquakes and
crustal movements are somehow related to sudden changes in the load
imposed on the earth's crust by meteorological conditions.
This conclusion is quite as surprising to the authors as to the
reader--perhaps more so. At the beginning of this investigation we had
no faith whatever in any important relation between climate and
earthquakes. At its end we are inclined to believe that the relation is
close and important.
Public-domain text, read in full here on John Shaqi.
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