Los Angeles herald., 1906-09-16
RECORDS
SHOW PLAINLY
SEISM0GRAPH AT BERKELEY
PROVES ITS WORTH
Disturbances in Chile, over Eight
Thousand Miles Away, Recorded
by instrument Owned
in Japan
Special to The Herald.

Special to The Herald.
BERKELEY, Sept. 15.-When Pro-
fessor Omori came to California to
April 18th, on behalf of his govern
ment, he brought with him a small
seismograph of his own design, called a
Promoter" The instrument consists
of pair of horizontal pendulums to
register earth movements in the EW
and MS components. The record is
made on smoked paper attached to a
drum which is made to revolve by
clockwork.
The time is recorded every minute.
The instrument is kept in constant mo-
ton. The object of Professor Omori
in bringing this instrument with him
was to set it up in a favorable loca-
ton for the study of after-shocks. The
after-shocks bear a certain, as yet un-
known, relation to the main shock.
Fore-shocks seem also to be related to
the main shock.
A study of the records of the fore and
after-shocks secured with the Tro-
meter may enable seismologists to
make predictions of time and place of
coming earthquake. While the in
strument is especially designed to
record slight fore and after-shocks
coming from a neighboring center, 1t
seems to be suited for records of heavy
earthquakes occurring at great dis
tance.
The Valparaiso earthquake was very
satisfactorily received at the Students
Observatory on the Omori Trometer.
Prof Omori selected the Students
Observatory for the installation of his
instrument because the rocky forma-
tion ON which the observatory rests Is
free from the unimportnat vibrations
which occur in soft ground. He offered
to leave the instrument here for two
years or more, on condition that 1t be
kept in running order and he be furn-
ished with duplicates of the records
The instrument belongs to the I'M
perial Earthquake Commission of
JAPAN and receipt for the instrument
has been forwarded to the commission
by the secretary of the university, In
accordance with Professor Omorfs re-
quest.
Good Records Secured
A number of very good records have
already been secured. They are of
great value to the State Earthquake
Investigation Commission. of which
Professor Lawson is chairman. The
| commission has set aside $25 per month
until October first to defray the cost
| of maintaining the Instruments. The
care of the instrument has been as
signed to Mr.. A. j. Champreux.
The various phases of the disturb
ances are marked on the record. From
! the length of the preliminary tremor
it is possible to calculate the distance
of the center of disturbance by a
| formula due to Omori. From two such
records made at different stations the
center itself may be determined. The
three principal phases of an earth
quake are the preliminary tremor the
principal portion and the end portion.
The record, as indicated on the print,
magnified the earth's motion 80 times,
but the instrument Is capa BILE of mag
nifying as high as 100 times.
In the case of the Valparaiso earth
quake the record Is distinct for over
two hours. Mr.. Champreux computed
the distance of the center of disturb
ance from Berkeley by Professor
Omori's formula, and found 1t to be
1884 miles, which agrees closely with
the direct distance of Valparaiso from
Berkeley