The Birmingham age-herald. [volume] (Birmingham, Ala.) 1902-1950, 1923-02-04

reaches across ASIA and the Mediter-
ranean. the mountains stills are
growing. In their growth large
masses comprising many thousand
cubic miles of rock are pressed
against each other, but are held by
friction until the strain becomes too
great. Then they slip and what is
called an earthquake occurs. This is
the modern theory of earthquakes. 1t
has been developed through pro-
longed studies and demonstrated by
observations of many minor quakes
and of the lines along which they
occur.
The earthquake plane is often
spoken of as a fracture, but 1t is
really not a break, recent statement
of the institution declares. 1t is the
surface between great masses which
never have been united, but which
for ages have been slipping past each
other; and where this plane comes to
the surface of the earth there is a
line called an earthquake rift The
greatest of these riffs in the United
States, so far as known, extends
along the coast ranges of California
for a distance of 500 miles. 1t passes
just west of San Francisco, to the
east of Los Angeles and disappears
in the Gulf of California. Along the
San Andreas rift, as Ii is called,
earth shocks have occurred at differ
ent times in different sections.
No Recent Movement.
South of that stretch for some 300
miles there has been no movement
since 1857 when severe shock oc-
Cured, the mark of which may still
be traced across the desert plains
like an irrigation ditch. Still fur
Their south there have been several
recent shocks, but none of great vio-
lence, although there is evidence OF
considerable activity in the section
east and west of Los Angeles.
For some years now, the Carnegie
institution has bene deep in the study
of earthquakes, and only recently or
ganized the advisory committee in
seismology, calling on the co-opera-
ton of many other scientists to AID
in the research. It's activities have
resulted in the discovery of many
facts of practical Importance TO man
kind in this connection. The Coop
GRAFTON of the United States navy was
obtained in making a depth-measur-
ing survey over a large area ada
cent to the California coast, and
while the survey was made to find
the trend of earthquake riffs, it re-
suited in important data for marines
and map makers. Through the finan-
cial ssistance of the Carnegie Foun-
dation of New York, DR.. Bailey VIII
lis, seismologist of Stanford Univer-
sity, was sent by the institution to
Chile to study, the aim being to ar
rive at the probable causes.
Riffs Located.
1t might be asked what value to
mankind will result from the expen-
diture of great sums for the study
of natural occurrence which, it is
admitted. can never be prevented and
which may continue to exact its toll
of human lives and property. In view
of the fact that scientists can now
locate the certain lines along which
quakes have occurred and seem sure
to occur again in future. they are
able to speak of live earthquake riffs
as they speak of live volcanoes. 1t
is known by the form of the volcano
or by the occurrence of eruptions
within historical time that it Is po--
tentially or actually active, and
much the same may be said of the
earthquake riffs.
They are lines of special danger
on which no school house. skyscraper
or dam should be built They should
be avoided. as far as possible, by
railroad lines. bridges. aqueducts and
other public works, and yet it hap-
pens that they often run through
valleys where such works are sug-
gested by the conditions of the
ground. AS long as builders remain
ignorant of their position they run
the risk of inviting destruction, IL
was added but it Is not difficult by
proper study to locate these lines OF
danger on a map and to make the
information public for the benefit OF
engineers and Others Indeed. there
is now being published an earthquake
rift map of the state of California,
showing the lines of active riffs ana
also Of faults that are supposed to
be inactive, as result of the work
carried on in cooperation with tho
institutions advisory committee.
That is how the engineers who laid
out the new water supply line for
San Francisco were able to remove II
from the former line. which followed
an active rift for miles, and locate 1t
along a mountain range, where, IL II
moves at all, 1t will move as block
and not become dislocated or de-
stroyed.