The Hawaiian star. [volume] (Honolulu [Oahu]) 1893-1912, 1902-10-07
DR., BISHOP WRITES
OF VOLCANOES
PRIMARY ERUPTIVE FORCE OF
VOLCANOES NOT STEAM, BUT
OCCLUDED CASES.
CFrom Nature, Sept. 4. 1922

CFrom Nature, Sept 4, 1902
The recent destructive eruption in
Martinique has revived interest in the
question of the causes of volcanic ac-
ton. Only lately have l become sensi-
BILE of the peculiar value of some OBJ
servations of my own as evidence of
the primary force which impels the as
cent of lava from its interior habitat,
as distinguished from the explosive
violence caused by steam generated by
the encounter of the ascending lava
with ocean and other surface waters.
l have long believed the primary
force to reside in the expansion of the
gases originally occluded in the mag
ma, ever since it's first condensation
from the nebula. Whenever released
from solidifying pressure by disturb
ances of the superintendent crust, the
intensely hot magma bursts into Wis
cid foam and pushes upwards In a
quiet volcano like our Kilauea, meet
ing no water to generate explosive
steam, the lava wells up continuously
and steadily in a comparatively gentle
fountain, which displays effervescence
only on the surface.
In support of this opinion l beg to
offer positive evidence contained in GER
tain facts observed by myself in XII
lauea during April STA 1892, and on
August rs, 1894. The volcano had been
in very steady and uniform action for
nearly two years before the earlier
date, and so continued until a short
time after the latter date, or nearly
five years in all of a quiet, continuous
and rather cOpious yelling up of lava,
wholly unattended by any explosive ac-
ton.
On the earlier date 1 carefully OBJ
served the then existing lava-lake dur
ing six successive days. This lake oC-
cupied the center of the inner crater,
called Halemaumau, or Fern-hut. The
main crater called Kilauea is nine
miles in circumference, averaging 400
| feet in depth, and rather unevenly
floored with recent lava. Southwest Of
the center is the inner pit of Halemau-
mau. This pit was at that time nearly
circular ana 240O feet in diameter, with
vertical sides averaging $50 feet down
to the talus. Before the yelling up of
lava began in 1890, the pit had been
about 700 feet deep. In two years the
lava had risen 400 feet, and stood with
in 300 feet of the rim and main floor.
A lake of liquid lava, covered by a
thin spongy film, occupied the center
of the pit. This lake was nearly cir
1t was bordered by a low dyke, which
partially restrained it's frequent over
flows. Outside of the dyke, freshly
concealed lava sloped away to the ia
lus. BY day the crust-fiim was grey to
the eye but by night a deep red. 1t
was traversed by numerous assures Of
white fire. During the whole time
three fountains of lava were yelling up
with somewhat regular intermittence,
and three smaller ones at irregular in
tervaIs. There was no explosive action
whatever.
The largest fountain was about 12O
feet southeast of the center of the
lake. 1t played with great regularity
about three times in a minute. rising
in a round billow 20 feet high and so
feet in diameter, bursting at the top
and falling back to level, its discharge
moving in a broad stream from its
summit rose to 40 or so feet above the
level.
West of this central fountain were
two others of very different character,
being more spasmodic in activity, but
never long quiet. Occasionally they
would unite their forces for half an
hour at a time, forming a stationary
line of 100 feet of spraying billow much
like a surf-comber with flying spray.
| y
high, necessarily flinging its spray 10
feet higher along its whole length. In
the night, the effect of these fountains
was extremely brilliant and was at
tended by loud metallic crashing.
The other three fountains were small
err near the borders of the lake. and
often quiet for hours together.
During the thirty months interval
between my two visits, the gradual
elevation of the fire-lake continued
quite uniformly, as attested by occa-
siOnal photographs. By it's frequent
overliows it had built itself up to a
height of fully 80 feet above the previ-
Gus main floor of kilauea, so that it
formed an extremely low truncated
cone, surmounted by the level lake, to
the edge of which visitors daily APP
preached.
About March, 1894, a recession began,
which ended in a final collapse of activ-
ity. The lake soon sank some hun
dreds of feet, carrying with it the sides
of circular pit, about 1400 feet in dia-
meter and central to the original 2400-
foot pit. When l saw it in the follow
ing September, the fire-lake was not
less than 500 feet below the rim. Dur
ing the evening, masses of rock fire.
quently crashed in, driving heavy sur
ges of fire far up the talus. There was
good deal of steam-cloud slowly ris-
ing, charged with sulphur. During my
previous visit, all vapour had seemed
to be absent, and l made the circuit of
the pit without encountering sulphur.
Subsequent photographs had also in
dicated the absence of vapour from the
| lake.
1 now have to add an important OBJ
servaton. To my great surprise, at
to In.F Cft I A.
three fountains above described were
in full activity and in the same rela-
tive position as before, although during
the thirty months the level of the lake
had risen $50 feet and had then fallen
800 feet. By what system of supply
ducts such fountains had been so long
maintained was a mystery concealed
in the fire-depths. But the fact of a
marvellous steadiness and uniformity
of action was obvious. For long per-
iod uniform and gentle outpour of
enerVescence had been maintained, 1t