The sun., 1900-08-12
PHILIPPINE EARTHQUAKES.
The Records Kept Of Them for Three Gen.
turies-work OF the Manila Observatory.


The Philippine Islands. like Japan. are in
a state OF almost incessant tremor. Most Of
these vibrations Of the earth's surface are so
slight that they can be observed only by sesmo-
graphs. the instrument invented for automati-
caly recording movements OF the earths crust
Many others are slightly preceived, but are
not recorded as earthquakes. for they do no
damage whatever and they are frequent
In earthquake countries that the general pub
lie pays little or no attention TO them. Some
time before the last nsurrectlon against Span
ish rule began. Mr.. NJ Saderra OF Manila COLI
lected all the historical notices Of earthquakes
in the Philippines that could be found in the
archives at the capital. They extended over
a period of nearly three centuries, from 1890
TO 1855, during which time nearly one thousand
earthquake shocks were recorded. II is quite
certain that In the list he collected only small
part Of the earth movements. that might prop
erly be called earthquakes. were included
The reason for thinking so Is that after the
establishment Of the Manila Observatory in
1885. when more careful observations began
TO be made. 4S7 earthquakes were recorded In
the thirteen years. ls88-79 This did not in
clude any seismograph records for these in
struments were not introduced till long after
the director Of the observatory that IT was
earthquake observation
II was not, however till 1887 that sesmo-
graphs were finally introduced and they were
in an almost constant state OF vibration till
the observatory was closed. on account OF
the war. in 1897. Now that better times are
dawning for the Philippines. 1t is to be hoped
that the work Of the observatory will soon be
resumed. for the islands are a very important
field for the study Of meteorology. terrestrial
magnetism and earthquakes.
Between 1889 and 1895 the seismographs
made many thousands Of records Of earth
movements, including minor earthquakes: and
there were forty-one shocks Of considerable
intensity which disturbed quito large areas
Maps were made showing the distribution OF
these disturbances and the extent Of country
affected In each case. A great deal Of data
with regard to earth movements in the Philip
pines were published In tho Monthly bulletin OF
the Manila Observatory after 1890. but no seis-
moloeist has yet undertaken the task of col
lating this material and summarizing the re-
suits 1t may be said. with regard TO our pres
ent knowledge OF earthquake phenomena In
these islands. that the observations thus far
are still insufficient In number and ReoRraph-
ical distribution for satisfactory conclusions
as to the seismic condition Of the archipelago
as a whole
In the long series Of volcanoes that stretch
from Kamptchatka through Japan and the
Malayan Archipelago in the form Of the letter
> to New Zealand the greater number Of them
are situated on the western side Of the islands
1t il also the western side Of the Philippines
and other islands that are most severely az
fected by earthquakes. The shores of Ma
Mia Bay. the northwest side OF Llzon and the
southern part Of the island suffer more fire.
auently than other parts OF Luzon. the largest
island in the archipelago. The most terrible
earthquake in the history of the Islands was
that Of 1853. when nearly all the public build
mas and European houses built Of stone in the
city Of Manila were leveled to the ground.
The shock Of 1880 is believed to have been
equally severe. but its effects were far less dis
astrous because the lesson taught by the ca
lamity OF 1853 had been utilized and the build
ings in the rebuilt city had been constructed
Oh a plan better adapted for resisting the ef-
fects Of these violent oscillations The shock
Of 1880 originated In the central part Of IlIzon
little east Of Manila and 1t was felt for a dis
tance Of about $50 miles north and south. more
or less damage being done all over the island
except in the extreme northern and southern
parts Of it.
In Mindanao the second largest island. there
are three zones where earthquakes are par
south, one running through the middle of the
island and the others alone the east and west
side, Generally speakine. the seyerest effects
are felt In the alluvial plains valleys not far
from the mountains, where more or less vol
canic phenomena are displayed.