apparently had its origin in or near Peru on May 9, to consider the
behaviour of a volcano, distant 5000 miles from this region, a week
before the disturbance took place. But although the coincidence may
possibly have been accidental, yet in endeavouring to ascertain
the true seat of disturbance we must overlook no evidence, however
seemingly remote, which may throw light on that point; and as the
sea-wave generated by the disturbance reached very quickly the distant
region referred to, it is by no means unlikely that the subterranean
excitement which the disturbance relieved may have manifested its
effects beforehand at the same remote volcanic region. Be this as
it may, it is certain that on May 1 the great crater of Kilauea, in
the island of Hawaii, became active, and on the 4th severe shocks of
earthquake were felt at the Volcano House. At three in the afternoon a
jet of lava was thrown up to a height of about 100 feet, and afterwards
some fifty jets came into action. Subsequently jets of steam issued
along the line formed by a fissure four miles in length down the
mountain-side. The disturbance lessened considerably on the 5th, and an
observing party examined the crater. They found that a rounded hill,
700 feet in height, and 1400 feet in diameter, had been thrown up on
the plain which forms the floor of the crater. Fire and scoria spouted
up in various places.
Before rejecting utterly the belief that the activity thus exhibited in
the Hawaii volcano had its origin in the same subterrene or submarine
region as the Peruvian earthquake, we should remember that other
regions scarcely less remote have been regarded as forming part of the
same Vulcanian district. The violent earthquakes which occurred at
New Madrid, in Missouri, in 1812, took place at the same time as the
earthquake of Caraccas, the West Indian volcanoes being simultaneously
active; and earthquakes had been felt in South Carolina for several
months before the destruction of Caraccas and La Guayra. Now we have
abundant evidence to show that the West Indian volcanoes are connected
with the Peruvian and Chilian regions of Vulcanian energy, and the
Chilian region is about as far from New Madrid as Arica in Peru from
the Sandwich Isles.
It was not, however, until about half-past eight on the evening of May
9 that the Peruvian earthquake began. A severe shock, lasting from
four to five minutes, was felt along the entire southern coast, even
reaching Antofagasta. The shock was so severe that it was impossible,
in many places, to stand upright. It was succeeded by several others of
less intensity.
While the land was thus disturbed, the sea was observed to be gradually
receding, a movement which former experiences have taught the Peruvians
to regard with even more terror than the disturbance of the earth
itself. The waters which had thus withdrawn, as if concentrating their
energies to leap more fiercely on their prey, presently returned in
a mighty wave, which swept past Callao, travelling southwards with
fearful velocity, while in its train followed wave after wave, until
no less than eight had taken their part in the work of destruction.
At Mollendo the railway was torn up by the sea for a distance of 300
feet. A violent hurricane which set in afterwards from the south
prevented all vessels from approaching, and unroofed most of the houses
in the town. At Arica the people were busily engaged in preparing
temporary fortifications to repel a threatened assault of the rebel ram
_Huiscar_, at the moment when the roar of the earthquake was heard.
The shocks here were very numerous, and caused immense damage in the
town, the people flying to the Morro for safety. The sea was suddenly
perceived to recede from the beach, and a wave from ten feet to fifteen
feet in height rolled in upon the shore, carrying before it all that it
met. Eight times was this assault of the ocean repeated. The earthquake
had levelled to the ground a portion of the custom-house, the railway
station, the submarine cable office, the hotel, the British Consulate,
the steamship agency, and many private dwellings. Owing to the early
hour of the evening, and the excitement attendant on the proposed
attack of the _Huiscar_, every one was out and stirring; but the only
loss of life which was reported was that of three little children who
were overtaken by the water. The progress of the wave was only stopped
at the foot of the hill on which the church stands, which point is
further inland than that reached in August, 1868. Four miles of the
embankment of the railway were swept away like sand before the wind.
Locomotives, cars, and rails, were hurled about by the sea like so many
playthings, and left in a tumbled mass of rubbish.
The account proceeds to say that the United States steamer _Waters_,
stranded by the bore of 1868, was lifted up bodily by the wave at
Arica, and floated two miles north of her former position. The
reference is no doubt to the double-ender _Watertree_, not stranded by
a bore (a term utterly inapplicable to any kind of sea-wave at Arica,
where there is no large river), but carried in by the great wave which
followed the earthquake of August 13. The description of the wave at
Arica on that occasion should be compared with that of the wave of
May, 1876. About twenty minutes after the first earth shock, the sea
was seen to retire, as if about to leave the shores wholly dry; but
presently its waters returned with tremendous force. A mighty wave,
whose length seemed immeasurable, was seen advancing like a dark wall
upon the unfortunate town, a large part of which was overwhelmed by
it. Two ships, the Peruvian corvette _America_, and the American
double-ender _Watertree_, were carried nearly half a mile to the north
of Arica, beyond the railroad which runs to Tacna, and there left
stranded high and dry. As the English vice-consul at Arica estimated
the height of this enormous wave at fully fifty feet, it would not seem
that the account of the wave of May, 1876, has been exaggerated, for a
much less height is, as we have seen, attributed to it, though, as it
carried the _Watertree_ still further inland, it must have been higher.
The small loss of life can be easily understood when we consider that
the earthquake was not followed instantly by the sea-wave. Warned by
the experience of the earthquake of 1868, which most of them must have
remembered, the inhabitants sought safety on the higher grounds until
the great wave and its successors had flowed in. We read that the
damage done was greater than that caused by the previous calamity, the
new buildings erected since 1868 being of a more costly and substantial
class. Merchandise from the custom-house and stores was carried by the
water to a point on the beach five miles distant.
At Iquique, in 1868, the great wave was estimated at fifty feet in
height. We are told that it was black with the mud and slime of the sea
bottom. “Those who witnessed its progress from the upper balconies of
their houses, and presently saw its black mass rushing close beneath
their feet, looked on their safety as a miracle. Many buildings were,
indeed, washed away, and in the low-lying parts of the town there was a
terrible loss of life.” In May, 1876, the greatest mischief at Iquique
would seem to have been caused by the earthquake, not by the sea-wave,
though this also was destructive in its own way. “Iquique,” we are
told, “is in ruins. The movement was experienced there at the same time
and with the same force [as at Arica]. Its duration was exactly four
minutes and a third. It proceeded from the south-east, exactly from the
direction of Ilaga.” The houses built of wood and cane tumbled down at
the first attacks, lamps were broken, and the burning oil spread over
and set fire to the ruins. Three companies of firemen, German, Italian,
and Peruvian, were instantly at their posts, although it was difficult
to maintain an upright position, shock following shock with dreadful
rapidity. Nearly 400,000 quintals of nitrate in the stores at Iquique
and the adjacent ports of Molle and Pisagua were destroyed. The British
barque _Caprera_ and a German barque sank, and all the coasting craft
and small boats in the harbour were broken to pieces and drifted about
in every direction.
At Chanavaya, a small town at the guano-loading dépôt known as Pabellon
de Pica, only two houses were left standing out of four hundred. Here
the earthquake shock was specially severe. In some places the earth
opened in crevices seventeen yards deep and the whole surface of the
ground was changed.
At Punta de Eobos two vessels were lost, and fourteen ships more
or less damaged, by the wave. Antofagasta, Mexillones, Tocopilla,
and Cobigo, on the Bolivian coast, suffered simultaneously from the
earthquake and the sea-wave. The sea completely swept the business
portion of Antofagasta during four hours. Here a singular phenomenon
was noticed. For some time the atmosphere was illuminated with a ruddy
glow. It was supposed that this light came from the volcano of San
Pedro de Atacama, a few leagues inland from Antofagasta. A somewhat
similar phenomenon was noticed at Tacna during the earthquake of
August, 1868. About three hours after the earthquake an intensely
brilliant light made its appearance above the neighbouring mountains.
It lasted fully half an hour, and was ascribed to the eruption of some
as yet unknown volcano.
As to the height of the great wave along this part of the shore-line
of South America, the accounts vary. According to those which are best
authenticated, it would seem as though the wave exceeded considerably
in height that which flowed along the Peruvian, Bolivian, and Chilian
shores in August, 1868. At Huaniles the wave was estimated at sixty
feet in height, at Mexillones, where the wave, as it passed southwards,
ran into Mexillones Bay, it reached a height of sixty-five feet.
Two-thirds of the town were completely obliterated, wharves, railway
stations, distilleries, etc., all swallowed up by the sea.
The shipping along the Peruvian and Bolivian coast suffered terribly.
The list of vessels lost or badly injured at Pabellon de Pica alone,
reads like the list of a fleet.
I have been particular in thus describing the effects produced by the
earthquake and sea-wave on the shores of South America, in order that
the reader may recognize in the disturbance produced there the real
origin of the great wave which a few hours later reached the Sandwich
Isles, 5000 miles away. Doubt has been entertained respecting the
possibility of a wave, other than the tidal-wave, being transmitted
right across the Pacific. Although in August, 1868, the course of the
great wave which swept from some region near Peru, not only across
the Pacific, but in all directions over the entire ocean, could be
clearly traced, there were some who considered the connection between
the oceanic phenomena and the Peruvian earthquake a mere coincidence.
It is on this account perhaps chiefly that the evidence obtained in
May, 1876, is most important. It is interesting, indeed, as showing
how tremendous was the disturbance which the earth’s frame must
then have undergone. It would have been possible, however, had we
no other evidence, for some to have maintained that the wave which
came in upon the shores of the Sandwich Isles a few hours after the
earthquake and sea disturbance in South America was in reality an
entirely independent phenomenon. But when we compare the events which
happened in May, 1876, with those of August, 1868, and perceive their
exact similarity, we can no longer reasonably entertain any doubt of
the really stupendous fact that _the throes of the earth in and near
Peru are of sufficient energy to send oceanic waves right across the
Pacific_,—waves, too, of such enormous height at starting, that,
after travelling with necessarily diminishing height the whole way
to Hawaii, they still rose and fell through thirty-six feet The real
significance of this amazing oceanic disturbance is exemplified by the
wave circles which spread around the spot where a stone has fallen into
a smooth lake. We know how, as the circles widen, the height of the
wave grows less and less, until, at no great distance from the centre
of disturbance, the wave can no longer be discerned, so slight is the
slope of its advancing and following faces. How tremendous, then, must
have been the upheaval of the bed of ocean by which wave-circles were
sent across the Pacific, retaining, after travelling 5000 miles from
the centre of disturbance, the height of a two-storied house! In 1868,
indeed, we know that the wave travelled very much further, reaching the
shores of Japan, of New Zealand, and of Australia, even if it did not
make its way through the East Indian Archipelago to the Indian Ocean,
as some observations seem to show. Although no news has been received
which would justify us in believing that the wave of May, 1876,
produced corresponding effects at such great distances from the centre
of disturbance, it must be remembered that the dimensions of the wave
when it reached the Sandwich Isles fell far short of those of the great
wave of August 13–14, 1868.
It will be well to make a direct comparison between the waves of May,
1876, and August, 1868, in this respect, as also with regard to the
rate at which they would seem to have traversed the distance between
Peru and Hawaii. On this last point, however, it must be noted that
we cannot form an exact opinion until we have ascertained the real
region of Vulcanian disturbance on each occasion. It is possible that
a careful comparison of times, and of the direction in which the wave
front advanced upon different shores, might serve to show where this
region lay. I should not be greatly surprised to learn that it was far
from the continent of South America.
The great wave reached the Sandwich Isles between four and five on the
morning of May 10, corresponding to about five hours later of Peruvian
time. An oscillation only was first observed at Hilo, on the east coast
of the great southern island of Hawaii, the wave itself not reaching
the village till about a quarter before five. The greatest difference
between the crest and trough of the wave was found to be thirty-six
feet here; but at the opposite side of the island, in Kealakekua Bay
(where Captain Cook was killed), amounted only to thirty feet. In
other places the difference was much less, being in some only three
feet, a circumstance doubtless due to interference, waves which have
reached the same spot along different courses chancing so to arrive
that the crest of one corresponded with the trough of the other, so
that the resulting wave was only the difference of the two. We must
explain, however, in the same way, the highest waves of thirty-six to
forty feet, which were doubtless due to similar interference, crest
agreeing with crest and trough with trough, so that the resulting wave
was the sum of the two which had been divided, and had reached the
same spot along different courses. It would follow that the higher of
the two waves was about twenty-one feet high, the lower about eighteen
feet high; but as some height would be lost in the encounter with the
shore-line, wherever it lay, on which the waves divided, we may fairly
assume that in the open ocean, before reaching the Sandwich group, the
wave had a height of nearly thirty feet from trough to crest. We read,
in accordance with this explanation, that “the regurgitations of the
sea were violent and complex, and continued through the day.”
The wave, regarded as a whole, seems to have reached all the islands at
the same time. Since this has not been contradicted by later accounts,
we are compelled to conclude that the wave reached the group with its
front parallel to the length of the group, so that it must have come
(arriving as it did from the side towards which Hilo lies) from the
north-east It was, then, not the direct wave from Peru, but the wave
reflected from the shores of California, which produced the most marked
effects. We can understand well, this being so, that the regurgitations
of the sea were complex. Any one who has watched the inflow of waves
on a beach so lying within an angle of the line that while one set of
waves comes straight in from the sea, another thwart set comes from the
shore forming the other side of the angle, will understand how such
waves differ from a set of ordinary rollers. The crests of the two
sets form a sort of network, ever changing as each set rolls on; and
considering any one of the four-cornered meshes of this wave-net, the
observer will notice that while the middle of the raised sides rises
little above the surrounding level, because here the crests of one set
cross the troughs of the other, the corners of each quadrangle are
higher than they would be in either set taken separately, while the
middle of the four-cornered space is correspondingly depressed. The
reason is that at the corners of the wave-net crests join with crests
to raise the water surface, while in the middle of the net (not the
middle of the sides, but the middle of the space enclosed by the four
sides) trough joins with trough to depress the water surface.[24]
We must take into account the circumstance that the wave which reached
Hawaii in May, 1876, was probably reflected from the Californian coast,
when we endeavour to determine the rate at which the sea disturbance
was propagated across the Atlantic. The direct wave would have come
sooner, and may have escaped notice because arriving in the night-time,
as it would necessarily have done if a wave which travelled to
California, and thence, after reflection, to the Sandwich group arrived
there at a quarter before five in the morning following the Peruvian
earthquake. We shall be better able to form an opinion on this point
after considering what happened in August, 1868.
The earth-throe on that occasion was felt in Peru about five minutes
past five on the evening of August 13. Twelve hours later, or shortly
before midnight, August 13, Sandwich Island time (corresponding to
5 p.m., August 14, Peruvian time), the sea round the group of the
Sandwich Isles rose in a surprising manner, “insomuch that many thought
the islands were sinking, and would shortly subside altogether beneath
the waves. Some of the smaller islands were for a time completely
submerged. Before long, however, the sea fell again, and as it did so
the observers found it impossible to resist the impression that the
islands were rising bodily out of the water. For no less than three
days this strange oscillation of the sea continued to be experienced,
the most remarkable ebbs and floods being noticed at Honolulu, on the
island of Woahoo.”
The distance between Honolulu and Arica is about 6300 statute miles;
so that, if the wave travelled directly from the shores of Peru to the
Sandwich Isles, it must have advanced at an average rate of about 525
miles an hour (about 450 knots an hour). This is nearly half the rate
at which the earth’s surface near the equator is carried round by the
earth’s rotation, or is about the rate at which parts in latitude 62 or
63 degrees north are carried round by rotation; so that the motion of
the great wave in 1868 was fairly comparable with one of the movements
which we are accustomed to regard as cosmical. I shall presently have
something more to say on this point.
Now in May, 1876, as we have seen, the wave reached Hawaii at about a
quarter to five in the morning, corresponding to about ten, Peruvian
time. Since, then, the earthquake was felt in Peru at half-past eight
on the previous evening, it follows that the wave, if it travelled
directly from Peru, must have taken about 13½ hours—or an hour and a
half longer, in travelling from Peru to the Sandwich Isles, than it
took in August, 1868. This is unlikely, because ocean-waves travel
nearly at the same rate in the same parts of the ocean, whatever
their dimensions, so only that they are large. We have, then, in the
difference of time occupied by the wave in May, 1876, and in August,
1868, in reaching Hawaii, some confirmation of the result to which we
were led by the arrival of the wave simultaneously at all the islands
of the Sandwich group—the inference, namely, that the observed wave
had reached these islands after reflection from the Californian
shore-line. As the hour when the direct wave probably reached Hawaii
was about a quarter past three in the morning, when not only was it
night-time but also a time when few would be awake to notice the rise
and fall of the sea, it seems not at all improbable that the direct
wave escaped notice, and that the wave actually observed was the
reflected wave from California. The direction, also, in which the
oscillation was first observed corresponds well with this explanation.
It is clear that the wave which traversed the Pacific in May, 1876,
was somewhat inferior in size to that of August, 1868, which therefore
still deserves to be called (as I then called it) the greatest sea-wave
ever known. The earthquake, indeed, which preceded the oceanic
disturbance of 1868 was far more destructive than that of May, 1876,
and the waves which came in upon the Peruvian and Bolivian shores were
larger. Nevertheless, the wave of May, 1876, was not so far inferior to
that of August, 1868, but that its course could be traced athwart the
entire extent of the Pacific Ocean.
When we consider the characteristic features of the Peruvian and
Chilian earthquakes, and especially when we note how wide is the extent
of the region over which their action is felt in one way or another,
it can scarcely be doubted that the earth’s Vulcanian energies are at
present more actively at work throughout that region than in any other.
There is nothing so remarkable, one may even say so stupendous, in
the history of subterranean disturbance as the alternation of mighty
earth-throes by which, at one time, the whole of the Chilian Andes seem
disturbed and anon the whole of the Peruvian Andes. In Chili scarcely
a year ever passes without earthquakes, and the same may be said of
Peru; but so far as great earthquakes are concerned the activity of the
Peruvian region seems to synchronize with the comparative quiescence
of the Chilian region, and _vice versâ_. Thus, in 1797, the terrible
earthquake occurred which is known as the earthquake of Riobamba, which
affected the entire Peruvian earthquake region. Thirty years later
a series of tremendous throes shook the whole of Chili, permanently
elevating its long line of coast to the height of several feet. During
the last twelve years the Peruvian region has in turn been disturbed by
great earthquakes. It should be added that between Chili and Peru there
is a region about five hundred miles in length in which scarcely any
volcanic action has been observed. And singularly enough, “this very
portion of the Andes, to which one would imagine that the Peruvians and
Chilians would fly as to a region of safety, is the part most thinly
inhabited; insomuch that, as Von Buch observes, it is in some places
entirely deserted.”