The San Francisco call., 1906-06-10
JAPANESE TELLS
OF EARTHQUAKES
Prof. Omori of Toxic
Lectures to Crowd
at Berkeley.
Imperial University Man
Discusses Peculiar
Phenomena.

tinguished experts in the field of seis-
attracted to the Students Observatory
tonight a throng that packed the hall
Professor A. c. Lawson of the Uniyer-
sity of California and Professor Omori
of the Imperial University at Toxic.
Japan, were the magnets. Colored
stereopticon pictures were used by Pro-
fessor Lawson to illustrate the points
made by him in his address upon earth
quakes in general and the recent earth
quake in particular Professor OmorI
used seismograph of his own inycn-
tion to Illustrate the features OF his
talk.
Professor Lawson, who is at the heao
of the geological department of the
State University, is conceded to be one
of the greatest authorities on earth
quake phenomena. and accordingly WAS
honored by Governor George c. Pardee
with the appointment of chairman OF
the earthquake commission formed last
April, and including famous scientists
of America. who were to study the pho
nomena attending the quake of April
Is and give to the world the benefit of
their Investigations. This commission.
through Professor Lawson. has made
preliminary report to Governor Pardee
regarding its investigations.
The address of Professor Lawson at
the Students Observatory tonight was
devoted almost entirely to an amplifica-
tion of the matter in this report TO the
Governor He added to the Information
contained in that report. however. the
interesting statement that the scientists
composing the earthquake commission
have discovered since the publication of
their preliminary report that tho rift
In, he
region affected by the earthquake iS
found TO have been affected by the tenn
bIor in Humboldt County. where its con-
dition had not heretofore been OBJ
served.
The commission had before stated
that the rift in question leaves the
coast and enters the ocean at Point
Arena It is now known that the rift
after entering the ocean. is found to
re-enter the land along the shore OF
Humboldt County. traces of it having
been found at Ferndale. Petrolia and IN
the upper Metole River Valley.
EARTH'S CRUST ELASTIC.
Professor Omori devoted his address
this evening to a general discussion OF
earthquake phenomena without partic-
uIar reference to the temblor of April
IS in California He told of his ex-
perience in studying earthquakes anf
/ cidSSlfXlng the pn6HO1eUd lIdl ctbCh0F
| them describing the instruments used
| to record these effects and his OVID
| share in the making of such apparatus
Professor Omori has been in California
| for three weeks Studying the ruin
wrought by the earthquake here, and
| will embody the results of his work in
| a report to the Japanese Government.
| In part, Professor Omori said:
The earthquake. motion. consists in
1 # sr-1l Gaf
! whose intensity ranges within wlde
| limits We shall find it convenient to
| divide the motion into two classes: the
sensible or marco-seiSmic. namely, that
which can be felt as trembiings or
| shocks; and the insensible or micro
seismic, namely, that which cannot De
| felt In the former, quick y1bratlons
coexist with slower ones, while in the
latter quick vibrations are either alb
| sent or extremely minute. Some oi
! the vibrations in the lnsensible motion
Vibrations in small but sensible local
/ earthquakes; they are jnsensibie only
because they are very slow
The earthS crust being regarded as
! an elastic medium through which seis-
mic waves are propagated, the investi.
] cation of these waves, OF their mode o'
! propagation, and their behavior under
! various circumstances from very i'm
/ portant branch of the physics of tht
earth, and especially the observations
Of distant ear1hguaKe giyes ay beIp "a. n
solution of some of the important prob
lens relating to the condition OF tn
earth's interior. By means ar OF n mdqerr s,a;ml
we can observe great earthquake IN
any part of the world. the motion dus
to such a disturbance lasting generally
| from 1 to hours.
NEAR EARTHQUAKES.
For the sake of reference T shall
state briefly the character of an ordj-
nary or sensible earthquake disturb
/ ance Such a motion, as observed wirt
| a seismograph begins always with VI
brations of small amplitude and com.
paratively short period These. arr
| usually known as the preliminary
to few minutes; next come those oi
| large amplitude, constituting the prin-
| cipal and most active part: and finally
the earthquake ends with feeble move.
ments, which may be called the end
/ portion. When the origin of the dis
/ turbance is near the observer. rumb-
ling sound like that of distant thunder
or a rushing sound like blast of wind
| is heard just before the arrival of stha
tremblings of the ground. These sound
phenomena, which are of frequent oc-
rare at places situated in plains. are
| probably due to the rapid vibrations
existing in the preliminary 'tremor. The
well known fact that some aflimala
before an earthquake is probably due
to their having an acute feeling and
/ DG1nK alarmed at the QESL SENSATIONS
of the preliminary tremor.
In slight earthquakes, the movement
of the ground is small. being a mere
! fraction of a tenth of an inch. When
! the motion reaches some half inch. the
earthquake becomes strong and may
cause slight damage. When the mo-
| tion reaches a few inches, the earth
| quake is already destructive and ordi-
nary brick houses. chimneys, ETC., will
| be considerably damaged The motion
| in the strongly shaken parts of San
probably inches
The preliminary trenlor, which con-
sists of small and comparatively quick
| vibrations is divided into the earlier
portion, or the first preliminary tremor,
and the later portion, or the second
preliminary tremor.
The principal portion denotes the
most active part of an earthquake,
which follows the preliminary trenors
and consists of larger movements. The
earlier part of the principal portion is
further subdivided into three success
sive stages as follows: Gao The first
phase. consisting of a few very slow
vibrations; tb) the second phase. con-
sisting of slow vibrations. which are
generally somewhat quicker than in
the first phase: Gel the third phase.
consisting of vibrations much quicker
than in the preceding two phases. The
third phase is followed by others Of
respectively the fourth. fifth. sixth
r,t.. of - mir,