On the Volcanic Phenomena of Hawaii
Authors: Williamson C. G. 
Published: October 2009

Abstract

T
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author describes the general configuration of the island of Hawaii, and refers especially to the arrangement of the three great volcanic cones which form its highest points. Mount Kea (13,953 feet) and Hualalai (10,000 feet) have been quiescent for many years*; but Mount Loa (13,760 feet) is still in a state of constant activity. In the extreme north of the island is the Kohala ridge of cones (about 5000 feet), which appear to have been long extinct. The bases of the three great volcanoes, which stand nearly in an equilateral triangle, are united by an elevated plateau forming the centre of the island, sparingly clothed with vegetation, and having many conical hills, from which lava appears to have flowed, scattered over it. In descending from the high grounds there is a belt of woods, in which the vegetation gradually becomes more tropical in its character; and this continues to be the case on the lowlands to the coast. The fertile districts are all within the limit of rains; and here the older lavas, of which the surface consists, are more or less decomposed. The author describes the general characters of the surface, and states that the greatest alteration of the surface has taken place in the northern parts of the island; hence he concludes that the centre of volcanic energy in the island has gradually been moving southward, the outpourings from the Kohala hills and Mount Kea, which have undergone most alteration, being, in his opinion, the oldest, and the southernmost volcano, that of Mount Loa (including Kilauea), being the only one now in activity.

The author notices the history of the activity of Mount Loa since the year 1832, when its first recorded eruption took place. A considerable eruption and lava-flow occurred in 1843, another of less consequence in 1851; and in 1852 a great lava-stream issued from the side of the mountain, at an elevation of about 10,000 feet, and flowed westwards for about thirty miles without reaching the sea. In 1855–56 the most extensive eruption on record occurred. The lava issued from a fissure on the western slope of Mount Loa, at an elevation of about 12,000 feet, flowed first in a north-westerly direction down to the central plateau, and then, turning westward, took the direction of Hilo. This lava-stream flowed for thirteen months, travelled a distance of sixty miles, and covered nearly 300 square miles of ground. In 1859 an eruption commenced at an elevation of about 9000 feet, from a crater 500 feet in diameter; the flow of lava continued for six months, passing across the central plateau in a north-easterly direction, skirting the volcano of Hualalai, and reaching the shore between Kiholo and Wainaualii, where it forms a distinct promontory. This lava-stream destroyed the village of Kiholo. The chief lava-flows from Mount Loa have taken a more or less northerly direction; and the author ascribes the lavas of the south-western portion of the island, especially the district of Puna, to the activity of the great crater of Kilauea (elevation 3970 feet), the appearance of which he describes. Eruptions of Kilauea took place, according to the author, in 1789 (consisting of sand and ashes without lava), 1823, and 1840.
The author notices particularly the great earthquakes and other volcanic phenomena of the year 1868. The first earthquake occurred on the evening of the 17th January; and the shocks continued to be felt, with more or less severity and frequency, throughout the year. The author noted those observed by him, with particulars of the time of the day at which they occurred and the strength of the shocks. The shocks were most frequent from the 28th March to the 6th April, during which period they appear, from the author's Tables, to have been almost incessant.
The greatest earthquake-shock took place on the 2nd April, at 3:40 p.m. The author describes this as excessively severe: the whole island appeared as if it were being shaken to pieces; walls and houses were thrown down, great masses of rock were precipitated from the cliffs, and large trees were broken off. Simultaneously with this earthquake a great mud-eruption is said to have taken place at Kapapala, although the author considers that the phenomenon really consisted in the casting down of a hill-top upon the plain. The débris extended over a space about three miles long, and varying from 500 yards to one mile in width. Over this space houses and cattle were buried, and 31 persons are said to have lost their lives. Immediately afterwards a stream of fresh water rushed down the hill-side, and continued to flow permanently. The author suggests that the sudden explosion by which this great earth-fall was produced may have been caused by the contact of water with the hot lava under the surface of the ground.
On the 7th April a rent opened high up on Mount Loa, and from this lava flowed. In the afternoon of the same day a fissure appeared in a hill about ten miles from the sea, in the district of Kahuku, near the southernmost point of the island. From this a stream of the smooth satin-like lava called “pahoehoe” in Hawaii flowed for a few hours, and then stopped. Another stream, of larger size, and consisting of the rough, porous lava known locally as “aa,” burst forth in the neighbourhood of that just mentioned, but about two miles nearer to the sea; it issued immediately behind the farmstead of the proprietor of Kahuku, which it immediately destroyed, and afterwards flowed down to the sea until the 12th of April, consuming everything in its course. About 250 head of cattle were burnt up. The lava was, described to the author as issuing from the ground in four enormous jets. The smoke and sulphurous vapour emitted during this eruption darkened and poisoned the air for a great distance around it. Soon after noon on the 4th of April, an earthquake-shock, almost equal to that of the 2nd, was felt; and this seemed to have affected the basin of Kilauea, which had previously been unusually active; for the lava-lakes sank down, and the fires gradually died out, until, on the 7th of April, none were to be observed. The coincidence of this sudden sinking of the lava in the crater of Kilauea with the breaking out of the great lava-stream at Kahuku, forty miles distant, seems, to the author, to indicate an intimate connexion between the two phenomena.
The great earthquake of the 2nd of April was accompanied by a destructive sea-wave, which washed away several villages, and destroyed many lives. The whole south shore of the island has been permanently depressed, in some places as much as 7 feet, but on the average about four and a half feet.