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Sydney Tyler.

San Francisco's great disaster; a full account of the recent terrible destruction of life and property by earthquake, fire and volcano in California and at Vesuvius .. online

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No exact theory for these adjustments has been formulated,
but two or three suggestions have been advanced as to the



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SAN Francisco's great disaster. 361

causes. Some think that the adjustments are due to the
earth radiating and a consequent shrinkage In the interior.

ROTATION OF THE EARTH.

"Others believe that they are due to the fact that the
earth is gradually slowing up in its rotations, causing a
flattening at the poles and a swelling at the equator, and the
crust of the earth is readjusting itself to this new shape.

Our mountain ranges provide the lines of upheaval in
these occasional readjustments. The vibration of a slip-
ping in the bowels of the earth naturally will extend over
a certain territory, the vibrations weakening in proportion
to the distance from the centre.

"The entire Pacific Coast region has been formed by
some violent upheaval at a time prehistoric even as geo-
logical periods go. The surface of the Pacific in those past
ages must have been much higher than its present level.
We know this, because we still can discover the traces of
beaches on the bluffs far above the sea. There has been
no rising of the North American continent south of Alaska
since it became the home of the white man. South Amer-
ica has been raised within the last century or so. There
we can still find shellfish clinging to the rocks far above the
sea.

The last change of some note that occurred on the
North American continent was about five years ago when
a section of Alaska about the Muir Glacier was hoisted
considerably by a seismic upheaval.

PROF. HOVEY'8 VIEWS.

Prof. Edmund Otis Hovey, Fellow of the American
Geological Society and Associate Curator of the Geologi-



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362 SAN Francisco's great disaster.

cal Department of the American Museum of Natural His-
tory, who visited Martinique after the recent eruption of
Mont Pelee and Soufriere, said:

"All the Pacific Coast is comparatively new territory.
Frequent seismic disturbances occur there owing to the
fact that the mountain-building forces constantly are at
work in this territory. Volcanic and seismic disturbances
only mark the efforts of rigid crust of the earth to con-
form to the contractions due to loss of heat beneath the
surface of the earth.

"San Francisco stands on g^round the foundations of
which were formed by ancient volcanoes. These volcanoes
date from such ancient ages that there are several other
geological formations on top of them and the volcanoes
are deep down below the surface of the earth.

"I hardly believe that this earthquake is of volcanic
origin. I would not be too positive. The nearest volcano
to San Francisco is Mount Shasta. This is about 250 miles
north of the Golden Gate, and has been extinct for cen-
turies. Mount St. Helena, 300 miles north, dominatiing
a part of Northern California and Southern Oregon, was in
eruption about sixty years ago. Several small volcanoes
in Northern California have been active in the last 100
years. We have little positive or first-hand knowledge of
these eruptions, and know of them only through later ob-
servations, because the region where they ar€ situated was
not inhabited by white men while they were active.

This disturbance possibly may be less severe, as far as
its effect on the surface of the earth is concerned, than
some of those which have preceded it. It did more damage
merely because it happened to strike San Francisco."

"These earthquakes very seldom occur in rapid suc-
cession. The most destructive earthquake recorded here



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SAN Francisco's great disaster* 3^3

in the last century was the one at Charleston in 1886, but
the most extensive was the one that occurred in 18 12, and
which is known as the New Madrid earthquake, because it
extended south from that town, following the bottom of
the Mississippi River. It created great changes in the sur-
face of the earth, forming a lake seventy-five miles long.

"Such disturbances are likely to occur as long as there
is any shrinkage under the surface, and that will go on
until the subterranean strata have settled and all tension
has been relieved."

According to Prof. Hovey, a German scientist who
for years has been experimenting to trace a possible con-
nection between barometric pressure and seismic distur-
bances following the mine explosion at Les Courrieres pre-
dicted a series of seismic and volcanic upheavals.

"It seems as though the prediction of the German
scientist has been verified, though I won't go so far as to
say that his theory, however interesting, has been vindi-
cated/' said Prof. Hovey

PROF. BERKEY'8 OPINION.

Professor Berkey of the Department of Geology at
C(dumbia University said:

"There is no possible connection between the eruption
of Mount Vesuvius and the earthquake at San Francisco.
Earthquakes are not necessarily of volcanic origin. The
earth'« crust in cooling contracts and often contracts un-
evenly, so as to cause the strata to slide. Such a sliding
may have caused the San Francisco earthquake.

"Some scientists hold that volcanic eruptions are
caused by a percolation of water from the sea into the
heated parts of volcanoes and that the steam thus gener-



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3^ SAN FRANCISCO*S GREAT DISASTEB.

atcd Starts the eruption. According to the theory now
generally accepted by scientists^ however, volcanic erup-
tions are caused by steam, but not from water percolating
from the sea, but from contact of the molten matter with
underground masses of water. Volcanoes thus become
the safety valves of the earth."

Prof. William Hallock of the Department of Physics
at Columbia holds with Prof. Berkey that a "sliding^' had
caused the earthquake in San Francisco.

MANY PACIFIC 8HOCK8.

From a perusal of the bulletins of the United States
Department of Geological Survey, it would appear that
earthquakes, though of very moderate violence, have been
of frequent occurrence in California and along the Pacific
slope. The record for 1896 shows fifty-five such distur-
bances. In 1897 not fewer than eighty earthquakes are
recorded. In 1898 there were twenty- four.

An odd circumstance manifest from the perusal of
these records is that there are more earthquakes in March,
April, May and June than in other months of the year. In
recent years the most severe earthquake occurred on
March 30, 1898. This disturbance did more damage to
property than any one that had occurred since the very
destructive one of April, 1892.

The earthquake of 1898 extended to Vallejo and
Benicia, but caused most destruction in 'the Mare Island
Navy Yard. It lasted only forty seconds, but in that space
of time destroyed nearly half a million dollars worth of
machinery at the Navy Yard. Only one San Francisco
building, that at 445 Qementina street, was destroyed, but
several \v?r^ damagr^*.



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SAN Francisco's great disaster. 365

Geologists agree that in the north of California, in what
is known as the Lassen PeaJc district, between the Sacra-
mento Valley and the Great Basin and adjoining the north-
ern end of the Sierra Nevada, there is a region sixty-nine
miles long and fifty-three miles wide in which the presence
of numerous hot springs shows volcanic activity in the
bowels of the earth. Throughout this district there is a
belt of volcanic cones some twenty-five miles wide and fifty
miles long, which recently has aroused the interest of scien
lists. Prof. Kemp of Columbia said that he did not believe
that there was any connection between the possible activi-
ties of this chain of volcanoes and the San Francisco earth-
quake. The latest eruption in this region, he said, occurred
some 200 years ago, when the Cinder Cone, near the centre
of the district, had a violent outbreak, the latest of note in
the North American Continent south of Alaska. Dense
forests have since grown up in this district on a seven-foot
layer of volcanic sand that was scattered all over the district
and destroyed all vegetation.

AN OPEN QUESTION.

In spite of the declarations of some scientists that there
can be no possible connection between the eruption of
Mount Vesuvius and the earthquake at San Francisco,
others are inclined to view certain facts in regard to recent
seismic and volcanic activity as, to say the least, suggestive.

In March there was a severe earthquake in the Island
of Formosa, and many lives were lost, while an enormous
amount of damage was done. A few days before the San
Francisco shock there was another earthquake in the same
island. Still greater havoc was caused by it than by the
earthquake in March, but fewer lives were lost, so far as is
known at present, the reason being that the people were
warned in time.



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366 SAN Francisco's great disaster.

Ten days before this disaster the eruption of Mount
Vesuvius reached its height and devastated the coun-
try around the volcano, covering an enormous territory
with ashes^ and caused the loss of hundreds of lives.

On Tuesday night, April 17^ word was received from
Piatigorsk, Ciscaucasia, that there had been two severe
earthquake shocks the previous day in Northern Caucasia.

The same night a teleg^ram from Madrid said that the
newspapers there reported that the long-dormant volcano
on Palma, the largest of the Canary Islands, was showing
signs of eruption, columns of smoke issuing from the crater.

There is one very remarkable circumstance in regard
to all this activity. All the places mentioned — Formosa,
Southern Italy, Caucasia, and the Canary Islands — lie with-
in a belt bounded by lines a little north of the fortieth
parallel and a little south of the thirtieth parallel. San
Francisco is just south of the fortieth parallel, while Naples
is just north of it. The latitude of Calabria, where the ter-
rible earthquakes occurred in 1905, is the same as that of
the territory affected by the earthquake in the United
States.

There is another coincidence which may be only a
coincidence, but which is also suggestive. The last pre-
vious great eruption of Vesuvius was in 1872, and the same
year saw the last previous earthquake in California which
caused loss of life.

Prof. W. H. Pickering of the Harvard Observatory,
says:

"There is no evidence that the disturbance on the
Pacific Coast is the result of any volcanic action, or that it
is in any way connected with the disturbances in other parts
of the world.

"Where earthquakes are caused by volcanic eruptions,



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SAN FRANaSCO's GREAT DISASTER. 369

the disturbance extends only within a limited area, not
more than a hundred miles or so. These are short and
very violent. For this reason the disturbances of Mount
Ranier in Washington State probably had no relation with
that at San Francisco, as it is too far away.

Earthquakes of the kind occurring at San Francisco
are caused by the slipping of strata at the ocean bed. This
is very probably the cause of the present disaster.

"The slope from the shore to the bed of the ocean is
very steep. This rests directly on the bed of the ocean, and,
as frequently occurs, cracks form at the junction. The re-
sult is a slipping of the whole formation to fill up the gap.

"This may occur at once or some time later. When it
does slip, the effect is felt in an earthquake on the nearest
shore. This is what has occurred at San Francisco.

"Such occurrences are more frequent on the Pacific
Coast than on the Atlantic, for the simp)le reason that the
slope is much steeper there. Japan suffers frequently for
this reason, and South America frequently sees such dis-
turbances."



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HOW EARTHQUAKES ARE RECORDED.

Scientists in all parts of the world are studying every
phase of natural phenomena, and among them none has
greater interest, or is more baffling than the earthquake.
The greatest stride ever made in this respect was the inven-
tion of the seismograph, the delicate instrument by which
are measured the vibrations of the surface of the earth, re-
sulting from earthquake shocks. This, to be sure, has no
(ralue in a premonitory sense. The seismograph gives no
hint of the approach of this destroyer; it merely records the
extent and duration of the shock or series of shocks. The
mighty throes of the Pacific Coast, when San Francisco
met her doom, was recorded wherever the slightest tremor
reached a seismograph. The instruments are costly and
are only in possession of a limited number of universities
and government observatories. In the great seismographic
division of the United States Weather Bureau at Washing-
ton, center of study, in America, of this branch of science,
the delicate instruments there recorded every pulse of the
California quake. The records, as they are made by the
seismograph are one of the chief reliances of scientists in
their efforts to solve the earthquake problem. Local evi-
dences, too, including changes in the contour of the earth,
fissures, the nature of the geological formations in the im-
mediate vicinity of the center of the disturbance, and other
features, largely visible, will aid. The opinion of scientific
men is divided on the question whether any appreciable ad-
vance will ever be made toward ability to predict seismic
disturbances. Most of nature's activities, even the most
erratic, follow immutable laws, and a few investigators
cling to the hope that even the earthquake obeys some in-



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SAN FRANCISC0*S GREAT DISASTER. ^7^

violable principle; results from causes not beyond human
ken, and these earnestly pursue their studies.

The "earthquake" division of the Weather Bureau,
mentioned above, is in charge of Professor C. F. Marvin,
one of America's greatest authorities on seismic topics.

On one of the weather bureau seismographs was made
a complete record of the great earth wave which brought
death and ruin to the fair city of San Francisco.

The delicate needle of the seismograph had been trac-
ing long, straight white lines on the gelatined surface of
the record sheet Wednesday morning, when it suddenly be-
came agitated at 8 o'clodc, 19 minutes and 20 seconds,
and began to make more or less elongated waves. At
8.25 o'clock the strong waves began, and the recording
needle moved rapidly back and forth across the sheet.
Then followed the most violent waves between 8.32 and
8.3s o'clock, 75th meridian time, as is shown by the record.
At one time the motion of the needle was so vigorous that
its point went off the sheet, which is kept in motion by a
clock machine, and the point did not return to the sheet
until there was a secondary lull in the great disturbance.
Then, when the needle had resumed its tracings, the earth
vibrations and waves continued until 12.35, when the agi-
tations ceased.

Each of the lines on the record sheet represents an hour
of time, the movement of the sheet keeping time with the
tick of the connected clock. The units of time are marked
on this sheet, which is covered with gelatine, and thus the
observer is enabled to tell just when the earthquakes began
and when they ended by the markings made by the needle
point.

The seismograph which Prof. Willis L. Moore, chief
of the weather bureau, has installed in his department is



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372 SAN FRANCISCO S GREAT DISASTER.

said to be one of the best in the world. It is installed in
a basement apartment away under the weather bureau
building, far removed from the noisy hurly-burly of the
streets, and is practically a mechanical recluse, only Prof.
Marvi and the immediate observers being allowed to invade
the sanctity of its subterranean home. For purposes of
exhibition and explanation a duplicate seismograph is set
up in a room adjoining the office of Prof. Marvin.

The weather bureau requires its observers to take care-
ful note of earthquake phenomena of sufficient intensity
to be felt at stations, but no specific effort has been made
to provide generally the instrumental means by which such
phenomena could be automatically recorded and measured.
The central office at Washington has, however, maintained
a simple form of seismograph in operation ever since De-
cember, 1892, and about three years ago greatly improved
its equipment by the installation of one of the large hori-
zontal pendulums made by J. & A. Bosch, of Strassburg,
and designed after the models of Omori.

OF A 8UPERIOR TYPE.

This instrument is of a very superior type and gives
an accurate record of the movement of the earth at the pen-
dulum in the horizontal plane. At the present time, but
one of the two pendulums constituting the set has been
installed and this produces a record of the north and south
component of horizontal motion.

The mechanical principles involved in the construction
of a seismograph of this type were first developed and ap-
plied to the measurement of earthquakes in the lat-
ter part of 1880 by James A. Ewing, then profes-
sor of mechanical engineering at the University of



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SAN FRANCISCO S GREAT DISASTER. 373

Tokio, but now professor of mechanism and applied me-
chanics at the University of Cambridge, England. Numer-
ous modifications have since been incorporated in the in-
strument by Gray, Omori and others, and in its present
form it is well adapted to measure and record all kinds
of earthquakes, except, perhaps, the most destructive, and
is especially suited to register the feeble, unfelt earthquakes
which frequently occur in all parts of the world.

The instrument in the basement room of the weather
bureau is installed on separate castings secured to thick
blocks of stone cemented firmly into the concrete floor of
the building and projecting but a few inches above the
floor level. The foundation of the instrument is separate
from the building, being far down in the earth so that it
will not be affected by artificial disturbances.

The extreme sensitiveness to tilting is exhibited in
several ways. The weight of the observer almost anywhere
on the floor of the small room in which the instrument is
installed suffices to tilt the pendulum enough to show on
the record. A large displacement is produced by standing at
one side of the pedestal. It has been noticed also that the
weight of an ice wagon wliich stops daily to deliver ice
at a basement entrance to the building causes a definite
displacement of the trace of about one millimeter, which dis-
appears when the wagon drives away. There are no vibra-
tions or oscillations registered, only a distinct elastic bend-
ing of the ground due to the load. This motion, more-
over is communicated through the foundation walls of the
building. The distance of the wagon from the seismograph
is about twenty feet ; the asphalted drive and the basement
floor are on the same level. The subsoil is a hard clay.

It may be added that the road is a private driveway



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374 SAN FRANCISCO S GREAT DISASTER.

back of the building and is rarely used, so that the effects
and disturbances of the record due to its proximity are not
regarded as interfering in the least with the validity of earth-
quake records.

"Aside from transitory tiltings of the ground of the kind
just discussed, others of a more gradual character are also
observed. If the pendulum were to remain absolutely
stationary during twenty-four hours the record sheet
would contain twenty-four straight parallel lines quite ac-
curately spaced three millimeters apart.

A PROGRESSIVE TILTING.

The spacingfs are never exact, but are sometimes quite
uniform. Generally, however, there is a distinct and pro-
gressive widening or narrowing of the spacings across the
sheet, showing that a slow, progressive tilting of the col-
umn or the ground has been in progress during the twenty-
four hours in question. While some of these displacements
must be attributed to temperature changes and effects en-
tirely within the instrument, yet slow tiltings of the ground
also occur, due to a variety of causes. The seismograph,
as now installed, answers every purpose for the registra-
tion of distinctively earthquake movements, but the slow
tilting referred to cannot be studied satisfactorily in the
present location of the apparatus, which for such purposes
should be isolated as far as practicable.

The earthquake wave recorded here, at such a long
distance from the real seat of trouble, was in the nature of
a long, regular motion, like a sea wave. The motion at
San Francisco was quick and sudden, and therefore very
destructive. This violent agitation produced destructive
strains, with the tendency to shake buildings to pieces,



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SAN Francisco's great disaster. 375

whereas at a distance where the movement of the earth is
slow and regular all portions of the building may follow
the motion of the ground. Prof. Marvin said, in illustra-
tion, that the passing of a rapidly moving railroad train
produces a vibration of the earth similar to that produced
at the place where an earthquake is causing destruction,
only in greatly reduced magnitude.

MANY U8E8 FOR 8EI8M0QRAPH.

One of the scientific purposes served by the use of the
seismograph is to throw light on the internal condition of
the earth — as to whether it is solid or liquid, or, if solid,
whether it is uniform or varying in constitution at different
depths or at different parts.

Among other uses the seismograph can afford in-
formation as to causes likely to interfere with submarine
cables. There have been instances of such interference
which, if it had not been for the seismograph, would have
been regarded as acts of war — ^the work of foreign enemies.
The instrument of course cannot be supposed to afford
absolute proof in such cases, for a cable might be broken
through some natural cause other than a local seismic dis-
turbance."

At the Kew Observatory the instrument now in use
was set up in 1898, being similar to the one Prof Milne had
in use for some time at Shide, in the Isle of Wight. During
the past eight years it has recorded over 600 earth tremors,
including most of the larger disturbances which have been
experienced in any part of the earth since 1898 — ^for in-
stance, the great earthquake in Nicaragua and the disturb-
ance due to the eruption of Mont Pelee, which led to the
destruction of St. Pierre, in the Island of Martinique, and



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376 SAK Francisco's great disaster.

the earthquake which took place on Jan. 31, on the same
coast line as the calamity in Colombia. The records show
that the disturbance of Jan. 31 began at 3.45 P. M. and
continued until after 6.30.

The records are made in this way: A horizontal rod,
or boom, pivoted at one end, supported by a cord and capa-
ble of swinging horizontally, is erected at the basement of
the observatory on a pier which passes through the floor
and rests on a concrete bed. The boom has at the free
end a rectangular plate, with a minute perforation
in the centre. A small gas jet is constantly burning over
the perforated plate, and sends light through the perfora-
tion and past the edges of the plate, falling on bromide of
silver photographic paper. The sensitized paper passes be-
low the plate at a uniform rate controlled by clockwork.
When the boom is at rest there appears upon the strip of
paper a thin, straight line, (representing the light which
has passed through the perforation,) and black bands repre-
senting the light which has passed over the edges of the
plate. In the event of a seismic disturbance the plate oscil-
lates^ and the original narrow straight line widens out,
forming a globe-shaped outline according to the amplitude
of the vibrations, while corresponding indents are shown
on the edges of the paper.

The exact situation of a disturbance is ascertained by
comparing the time at which corresponding observations
are made at other observatories. At each half hour a small
hand comes in front of the light, and interrupts it at one of
tfie margins of the sensitized paper. Should there be a dis-
turbance, in the neighborhood of Mont Pelee, the earliest
movement would be recorded at Kew before it would reach
St. Petersburg; whereas, if it originated in Central Siberia,


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Online LibrarySydney TylerSan Francisco's great disaster; a full account of the recent terrible destruction of life and property by earthquake, fire and volcano in California and at Vesuvius .. → online text (page 21 of 25)