The year recently closed furnishes interesting corroborative testimony
of an apparent law regarding the propagation of earthquake movements
_most readily_ along great circles of our globe, as well as evidence
that these seismic movements are frequently transmitted along belts
(approximating to great circles) coincident sometimes with continental
trends, at other times with fissures which emanate in radii at every
30°, around the pole of the land hemisphere in Switzerland, as described
in one of my papers, read at the Montreal meeting of the A.A.A.S.
The terms synchronism or synchronous, as here used, are not designed to
imply absolute simultaneity (although that is sometimes the case with
disturbances 180° apart), but are rather intended to indicate the
tendency presented by these phenomena to exhibit this internal activity,
during successive days, weeks, or even months, along a given great
circle of the earth, especially one or more of those connected with the
land center; perhaps most of all along the great circle which forms the
prime vertical, when the center of land is placed at the zenith.
In order to test the above, let us examine the record of the most
prominent earthquakes or volcanic eruptions for the year 1883.
Late in Dec., 1882, and early in Feb., 1883, shocks occurred in New
Hampshire; on Jan. 11, 1883, also at Cairo, Illinois, and about the same
time at Paducah, Ky.; Feb. 27 at Norwich, Conn., and early in Feb. at
Murcia, Spain.
These, by examination of any good globe, will be found on a belt forming
one and the same great circle of the earth.
Late in March and during part of April the volcano of Ometeke in Lake
Nicaragua was active (after being long dormant); Panama, portions of
the U.S. of Colombia, and of Chili; also, in May, Helena, M.T.; and,
in June, Quito (with Cotopaxi active) were all more or less shaken by
earthquakes; and are all found on one belt of a great circle.
The principal record for the remainder of the year comprised:
An earthquake at Tabreez in North Persia, early in May, 1883.
The awful destruction in Ischia, July 29 (with Vesuvius active).
The fearful eruption in the Straits of Sunda, 25th Aug. and later.
Shocks in Sumatra and at Guayaquil, about same date or early in Sept.
Shocks at Dusseldorf, according to a Berlin paper of 5th Sept.
Shocks at Santa Barbara and Los Angeles, early in Sept.
Shocks at Gibraltar and Anatolia in October.
Shocks at Malta, Trieste, and Asia Minor in October.
Azram shaken late in Sept., and great destruction between Scios and
Smyrna.
Lastly, the formation of a new island in the Aleutian Archipelago. Date
of outburst, early in October, 1883.
Besides these, there were several other less severe disturbances, the
records of which are chiefly obtained from Nature, and which will-be
referred to below.
If the globe be so placed as to have the land center at the zenith, the
exact position of the new island, near Unnok, will be found under the
brazen meridian, while Agram, Tabreez, Sunda, Sumatra, Quito, and
Guayaquil are all on the prime vertical.
Vesuvius and Hecla were both active early in the year, and they, with
the ever restless Stromboli, are situated on the great circle which
forms with the land center at Mount Rosa, the radius running S. 30° E.,
and which would embrace the chief disturbances up to the middle of the
year, including as we go north Malta, Sicily, Rome, region of the Po,
Bologna, and in the Western Continent, after passing Hecla, Helena in
Montana Territory, reaching in Washington Territory and Oregon the belt
of it. American volcanoes: Mounts Baker, Rainier, St. Helens, Hood, and
Shasta.
Still another seismic belt, starting from the ever active Fogo, and
passing through Teneriffe (at that time erupted), would include the
regions disturbed in Oct. and Nov., namely, Cadiz, Gibraltar, Malaga
(Murcia and Valencia somewhat earlier); it then traversed the center of
land, caused the earthquakes at Olmutz in Moravia, and even tremors felt
at Irkutsk, as the seismic war moved along said great circle to the
volcanic region of S. Japan.
Again, the belt which covers the meridian of land center (about 8°-10°
E. long) covers also the region of a disturbanced area in Norway, as
well as that portion of Algeria, viz., Bona, in which a mountain 800
meters high, Naiba, is gradually sinking out of sight. About 100 geo.
miles E. of Bona is where Graham's Island appeared in the Mediterranean,
and a few months later disappeared in deep water.
Another highly seismic belt extends from the volcanoes of Bourbon, N.
Madagascar, and Abyssinia to Santoria and the oft disturbed Scios,
Smyrna, and Anatolia region; and along the same great circle were shaken
Patra in Greece on the 14th Nov., and Bosnia on the 15th; while shocks
had been felt at Trieste and Mülhouse about the 11th, and at Styria on
the 7th, and disturbances at Dusseldorf in Sept. Finally, on the 28th
Dec. S. Hungary (near the confluence of the Drave with the Danube) was
visited by seismic movements along this same great circle, which passes
through the extinct volcanic region of the Eifel, the oft shaken Comrie
in Perthshire, Scotland, the volcanic Iceland, our National Park with
its thousands of geysers, the cataclysmic region of Salt Lake and the
Wahsatch Mountains (so graphically described by the geologists of the
U.S. Geol. Survey), giving rise in Sept. to the earthquakes of Los
Angeles and Santa Barbara, and finally reaching the volcanic islands of
the Marquesas group.
Thus the seismic efforts of 1883 may be seen to have expended their
force partly along the great backbone of the S. and N. American
Cordillera, but more especially from the center of land E. and W. along
its prime vertical from Sunda to Quito, also southwesterly by the E.
coast of Spain, as well as due S. through Algeria, and S. 30° E. through
Rome, Naples, Sicily, etc. Finally, the autumnal catastrophes at and
near Scios, Anatolia, etc., seem to have been caused by a seismic wave,
propagated along the great circle, which often agitates Janina, and
produces earthquakes at Agram, where this great circle crosses the prime
vertical.