, 1908-06-03
THE JAMAICA EARTHQUAKE
(1gricultau.aL News.)

4 further extract from DR.. Vaughan Cor
nish's paper, dealing with the character and
results OF the Jamaica earthquake, is given
below, IN continuation of the notes which
appeared in the last issue of the 1gricaItu1-
1T Neoos, describing the personal experience
OF the author in Kingston at the time Of the
disaster =
The economic Importance of the Jamaica
cal Shquake of January IA, 1907, is due to the
destruction Of Kingston and it's suburbs, and
it IS in and around the city that the effect
If seismic shock upon buildings can best
be studied. Viewed, however, from the
physical standpoint, the importance OF an
earthquake is independent Of the neighbour
hool Of cities.
I think | shall be able to show that the
Jamaica earthquake was essentially double
harrellod, SO to speak that Kingston was
brought down by one barrel, and that tbs
other barrel was discharged in q thinly pop
ulated district, where it consequently did
mucu less damage but that when we ex-
anime the seismic effects in parts Of the
island distant from either Of these foci, we
find that they are, on the whole, about aa
much due to the one part of the double
shock as to the other, the charge in the two
barrels, 50 to speak, being about equal.
From the physical standpoint, therefore, the
Kingston earthquake is not quite the same
thing as the Jamaica earthquake.
Thirty seconds IS the duration currently
assigned to the earthquake at Kingston,
but no one really timed it there. At Kelita,
about 35 miles north west of Kingston Mr..
Horn informs me that the earthquake, timed
with o watch, lasted 81 aecon is, this space
of time being divided as follows, viz II
seconds shaking, 13 seconds rolling, and
again 7 seconds shaking, which finished
with u distinct jerk. AT Bethany, about As
miles northwest Of Kingston, DIR. Har-
greaves informs me that he timed the earth
quake by Il second5-hand watch, and found
that it lasted 80 seconds.
| have described the character of
the vibrations which / experienced in
q top story corner room Of a brick house
I'll East Street. These were only in q
secondary sense due to the earthquake, the
immediate cause being the action of The
vibration of the massive walls upon the
wooden floor. The movement of the
ground was well observed opposite the old
Mlco. IN Hanover Street, by Sub-Inspector
Tremlett, and near the south end of Johns
Lane by.Mr. Sullivan. In addition to any
Earring or humping, there was a strong swell
literally u ground swell-running from
west to east or from east to west. Mr.. Sui
Ivan says the west-to-east roll was much
stronger that the return roll from east to west.
The impression generally received was that
these surface nndulations were only q few
yards from crest to crest, and they certainly
succeeded one another several times in o
second. The height from crest to crest ap-
peared to be several inches, so that their
steepness was very co siderable. AS far as
/ am aware, the only instrumental evidence
as to the periodic time of the earthquake
oscillations is that afforded by the transmitter
OF the West India Direct Cable to Kingston.
l learnt that it had continued TO run for a
time before the offce collapsed, and that the
strip of paper had been sent to the Lon
don office as a curiosity. / therefore
timed the running of the machine in King.
ston, and afterwards in London was allow ed
to measure the oscillations of the writing pen
as recorded IN the strip of paper. There
were ten complete north oscilla-
tons in the first two and a half seconds, j. g.
four per second. Tie position of the instru-
ment did not permit it to record east-and-
west vibrations.