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Phenomena observed at the Outburst.
The amount of information which has been recorded as to the actxsual outburst is very considerable, but all through there appears to be a want of exactness as to the times and order of occurrence of the phenomena observed, a very natural result of the excitement and confusion into which people would be thrown by occurrences which threatened their very existence. But the best accounts obtainable seem to place the first signs of anything extraordinary happening, at about 1 a.m. on the 10th June, 1886, when slight earthquake shocks were felt by the people at Wairoa, and at Rotorua, (accompanied at the latter place by rumbling noises), which appear to have been continued as earth-tremors till 2 a.m., or past. At 2.10 or 2.20 the rumbling noise had become a continuous and fearful roar, accompanied by a heavy shock of earthquake; and at this same time, or immediately afterwards, an enormous cloud of smoke and vapour was observed from Wairoa, rising over the hills which shut in that village from a clear view towards Tarawera Mountain, the outside edges and fringes of the different masses of which were outlined by vivid flashes of electricity, darting through the cloud and colouring it most brilliantly and beautifully. This electric display was accompanied by a rustling or crackling noise, which appears to have been heard above the deafening roar, and which is probably the same noise as is heard in electric discharges of an artificial kind, and also probably the same as is heard sometimes at great auroral displays. This heavy shock of earthquake is doubtless the same as that reported at Maketu at 2.30, Tauranga 2 a.m., and Makarewarewa at 2.30. It was noted by two observers, (Messrs. Blythe and Greenlees), that from 2.30 onwards severe shocks occurred at regular ten-minutes' intervals up to 3.30. The latter gentleman had the presence of mind to observe, from the swinging of a ham, that the shocks came from the direction of Tarawera. It is probable that the eruption of Tarawera first took place in any strength at about 1.45 a.m. As described by Mr. McRae, who saw it from the old Mission Station, soon after the outburst, three columns of fire and flame (or probably the glare
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reflected on the vapour from lava below) were shooting upward from the flat plateau-like summit of the mountain to an immense height, with flashes of electricity darting forth in all directions, accompanied by balls of fire, some of which fell at great distances, indeed as far off as the Wairoa village, some 8 miles from the seat of eruption. Small stones now began to fall, as the great black cloud which had formed over the mountain worked towards the west, to be quickly followed by a downpour of mud and water and heavy stones, which battered down many of the houses in the village. The mud appears to have fallen in the form of an exceedingly heavy rain, with sometimes large lumps of mud, and this continued up till 6 a.m. All this time, there appears to have been a more or less strong odour of sulphur experienced by the people at Wairoa; and Mr. Blythe describes a hot suffocating blast, which nearly choked himself and Miss Hasard, after their escape from the burning house, and which warmed them through.
Soon after the first outburst, and before the fall of the first stones, a great wind arose, which rushed in the direction of the point of eruption with great force, and was most bitterly cold. It is noticeable that the people who survived, and were nearest to the seat of the eruption, viz., those at the Wairoa, failed to hear the loud detonations which reached Auckland and other places. Probably the loud and continuous roar drowned the louder reports.
These explosions were heard at Hamilton, Cambridge, Lichfield, Coromandel, Te Aroha, Wanganui, Tauranga, Maketu, Taupo, Christchurch, Wellington, Nelson, Blenheim, Whakatane, Opotiki, Auckland, New Plymouth, Whangarei, and Helensville, and sounded like the reports of distant cannon, or—as has been described by a large number of people from different places—like some one banging an iron tank. The flashes of the electric display were distinctly seen here in Auckland, a distance of 120 miles in a straight line from Tarawera. The immense cloud of ashes, mud, and sand which was shot high up into the air darkened the sky till long after daylight should have appeared. It is stated that it was quite dark at Rotorua till 7.30, (the ashes commenced falling there at 4 a.m.), and again at 9 a.m.; at Opotiki till 10 a.m., at Tauranga till 9 a.m.; at Te Puke it is said to have been dark as late as 2 p.m. on the 10th; at Maketu till 10 a.m.; the ashes beginning to fall there at 5.30 a.m. The height to which the mass of light ashes was ejected must have been enormous. Professor Verbeek, who was appointed by the Dutch Government to report on and describe the eruption of Krakatoa in May and August, 1883, states that the column of steam arose from that eruption to a height of 50,000 feet, or over 9 miles. The dark cloud of dust and ashes from Tarawera must have been nearly as high as this column of
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steam. Mr. R. Arthur, of Mount Eden, who had a distinct view of the cloud illumined by electric flashes on the morning of the 10th, took notice of the height which it appeared as seen behind One Tree Hill; and the angle of elevation, as afterwards measured by Mr. Vickerman, of the Survey Department, gives a height, as computed by him, of 44,700 feet above Ruawahia, or a little over 8 miles. Although this method of observation is not a very accurate one, and may not be quite correct, it gives some approximation to the height.* We know from actual measurement that the column of steam arising from Rotomahana several days after the eruption was 15,400 feet, and even then the top of the column could not be seen, from its proximity to the observer. The ashes and dust ejected fell on the coast line at points 160 miles apart in a straight line—viz., at Tairua and at Anaura, a few miles north of Gisborne, and some of it fell on the s.s. “Southern Cross” off the East Cape, and on the s.s. “Wellington” near Mayor Island. It thus covered an area of land equal to 5,700 square miles with more or less of the deposit; on the edges of which, of course, it is barely visible.
In thus calling attention to the great height to which the dust and ashes were projected by the explosive force of the steam, a distinction must be drawn between this height and that mentioned by Professor Verbeek. In the Tarawera case this refers to the top of the cloud of ashes; in that of Krakatoa to the column of steam seen long after the eruption. Nor must it be inferred that in the New Zealand eruption we shall necessarily see the same extraordinary and beautiful atmospheric effects which followed the Sunda eruption.
The electric phenomena accompanying the outburst must have been on the grandest scale. The vast cloud appears to have been highly charged with lightning, which was flashing and darting across and through it: sometimes shooting upwards in long curved streamers, at others following horizontal or downward directions, the flashes frequently ending in balls of fire, which as often burst into thousands of rocket-like stars. Fire-balls fell at the Wairoa and other places, and doubtless the fires which occurred at Mr. Hazard's house and in the forest near Lake Tarawera were due to these.
[Footnote] * Archdeacon Williams, of Gisborne, who saw the flashes of lightning on the 10th, calculates that they were seen at an elevation of 6 miles.