The sun. [volume] (Morris, Stevens County, Minn.) 1882-1895, 1886-10-07
SEISMIC DISTURBANCES.
A Subject that Has Been Care
fully Studied Only During the
Last Thirty Years.
Duration and Velocity Of Earthquake
Shock1-Their Relation to Vol
oanic Eruptions.
Unreliable Signs.


oanio Eruptions.
Unreliable Signs.
The earthquake shock which has done
so much damage during the last thirty
six hours at the south. especially in the
stricken city of Charleston, 5. c., is the
severest that has been felt on the east
ern coast of America during the present
century, writes w. lie Conte Stevens in
The New York World, and scarcely, if
at all. surpassed in violence by any on
the Pacific coast of our continent. Its
effect seems to have been felt over
nearly the whole area of the United
States east of the Rocky mountains.
The intense popular interest just now
excited in phenomena of this class
makes it important that a brief general
discussion of earthquakes be given in
connection with the recital of those ter
rible events. that will be remembered
throughout the lifetime Of all whose
homes have been desolated or whose
friends have been exposed to peril.
An earthquake is commotion pro-
pogated through the earth's crust in
all directions from some source of dis
turbance. in waves that outcrop on the
surface and are manifested in percepti-
BILE motion of the ground. They vary
in intensity from gentle tremblings. re-
quirlng delicate instruments for their
detection, to commissions Of terrific vi
olence, capable of destroying the most
substantial products of human labor.
During the last thirty years the study
of earthquakes has been developed
into special branch of science, to which
the name seismology has been given.
The first man who gave the world any
reliable scientific discussion of such
Phenomena was Mr.. Robert Mallet, of
England, who visited Naples immedi-
ately after the earthquake which de-
sstated southern Italy in 1857. In his
subsequent labors he received impor-
tant aid from his son, DIR. John w.
Mallet. whose name has since become
prominently associated with the pro-
gress of chemical science in America.
The number of investigations in recent
years has been greatly multiplied. In
struments have been devised for meas
uring the intensity of shocks and of re-
cording the direction and reg STEERING
the time of transit. In regions where
earthquakes are of frequent occurrence
such seismometers are distributed at
many points and kept in constant read
mess. 1t is from systematic records
from these that we derive our most i'm
portant information to-day.
America is fortunately not often
shaken, and the number of eismome-
tiers kept in readiness in our country is
too small to assure us of accurate
knowledge regarding the recent shock.
Earthquakes occur in all parts Of the
world, but are most frequent in mcun-
famous regions, and especially those of
volcanic activity. In many cases the
shocks are directly the consequence of
volcanic eruption, but they occur also
in PLACES and under circumstances that
indicate not the least connection with
volcanoes. This seems to be true of
the recent Charleston earthquake.
The Andes region of South America
and the southern part of Italy include
some of the worst shaken districts in
the world, and some of the most active
volcanoes. But among them earth
quakes often occur without the exhibit
ton af any unusual volcanic activity.
The earthquake which was 50 destruc-
tive to life and property a few days
ago in Greece and Italy was imme-
diately followed by commotion in the
crater of Vesuvius. 1t is safe to say
that the same cause may give rise to
both volcanoes and earthquakes, but
neither of these implies the other nee
essarily. Ths Himalayas and table
lands of Central Asia are subject 10 Vi
olent earthquakes. but almost free
from volcanoes. The Alps and Pyre-
nees are often shaken, but include nc
VOLCANOES that are not extinct The
same is true of the American Pacific
coast range south of the Columbia river.
Non-volcanic basins, such as the val
ley Of the Mississippi and the basin Of
the Baltic sea, have been roughly sha.
ken. Earthquakes are most Fare ir
Russia, which consists mostly of low
plain free from mountains.
The region most shaken within the
past two days is near the southern ex
tremity of the Allegheny range. 1t ii
too early yet to form any reliable est.
mate of the point where the disturbance
originated.
Mr.. Mallet collected catalogue o
between 5000 and 1000 earthquake
recorded between the periods B. G.
1906 and A. d. 1850. This is obviousl,
a mere fraction Of the number that &C
Cured between those dates Sine
} 1850 the number of earthquakes record
ed has greatly increased, though ther'
is no reason to believe that there is an,
increase in actual frequency of shocks
BY the use of seismometers in Italy,
Japan, and elsewhere it has been prov
ed that in such regions scarcely q day
passes without A noticeable eartl
tremor. Probably not q memen
elapses ws-...thout an earthquake in sem'
part of the world. The surface Is con
tinually in CULVER. but fortuna..ei !.
such titanic agues as those that throw
down cities are comparatively rare.
No one cause can be properly an
nounced as fully accounting for al
earthquakes. BY far the most frequen
is the breaking of the carth's crust un
der the same surface contraction tina
squeezes out lava from volcanoes an
folds the regions of weakness int
The no~th nnufi mo