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The Pamphlet Collection of Sir Robert Stout: Volume 67

The Eruption

The Eruption.

Wednesday, the 9th June, was wet, with heavy showers and squalls from the south-west, which cleared up by nightfall. The evening was fine, allowing many to see the occultation of Mars by the moon, which occurred at 10.20 that night. There had been some rain during the previous week, but no great amount, and this was the first rain of winter after a long dry summer.*

The readings of the self-registering barometer at Rotorua showed no sign of atmospheric disturbance, as will be seen by the following table, the readings being reduced to sea-level: 8th June, at noon 30.2in.; at midnight, 30.08in.: 9th, at 6 a.m., 30.03in.; at 10 a.m. 29.97in.; at noon, 29.90in.; at 6 p.m., 29.80in.; at midnight, 30.01in.: 10th, at 2 a.m., 30.01 in., (eruption); at 4 a.m., 30.20in.; at 6 a.m., 30.30in.; at noon, 30.30in.

The description of the phenomena observed at the actual eruption is taken by permission from a paper read before the Auckland Institute by Messrs. S. Percy Smith and J. A. Pond, on the 12th July, with some additions and alterations derived from subsequent inquiries by the writer.

The best account obtainable seems to place the first sign of anything extraordinary being at hand at about 1 a.m. on the morning of Thursday, the 10th June, 1886, when slight earthquake-shocks were felt by the people of the Wairoa, a village situated just eight miles from, and nearly due west of, Mount Tarawera; and also by those of

* The rainfall for June, as registered at Rotorua, was 4.74in. (Vide New Zealand Gazette, 1886, page 1296.)

page break Barometrical Record at Rotorua 1886 page 27 Rotorua—accompanied at the latter place by rumbling noises—which appear to have been continued with varying degrees of intensity up to 2 a.m. or past. At 2.10 or 2.20 the rumbling noise had increased to a continuous and fearful roar, and at that time was accompanied by a heavy shock of earthquake. At this same time, or immediately afterwards, an enormous cloud of smoke and vapour was observed from the Wairoa rising over the hills which shut in that village from a clear view towards Tarawera, the outside edges and margins 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 repeated claps of loud thunder, and by a rustling or crackling noise which appears to have been distinctly heard above the deafening roar, and which is probably the same as that heard in electric discharges of an artificial kind, and also in auroral displays. This heavy shock of earthquake is, doubtless the same as that reported at Maketu at 2.30, Tauranga at 2, Whakarewarewa at 2.30, Opotiki at 2, and Oropi at 2.30 a.m., the differences of time being due to local inaccuracies of clocks. It was noted by two observers—Messrs. Blythe and Greenlees—that from 2.30 onwards severe shocks occurred at regular ten-minute intervals up to 3.30; and it was between these hours that the outburst at Rotomahana occurred, for Mr. Blythe noticed that the white cloud of steam arising therefrom was first seen about 2.30, that from Tarawera being black by contrast. It is proved by several witnesses that the eruption of Tarawera took place first; and Mr. McRae, of the Wairoa, who witnessed the scene, shortly after the first outburst, from the old mission-house, believes this to have been shortly before 2 o'clock. As seen by himself and others, this consisted of three columns of smoke and fire—or probably the glare reflected on the vapour from the heated lava below—shooting up into the air 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, whilst others appeared to roll slowly-down the steep sides of the hill towards the lake. Small stones now began to fall at the Wairoa and at Kaiteriria, as the great black cloud which had rapidly formed over the mountain worked its way towards the west, to be quickly followed by a downpour of mud and water and occasionally heavier stones, some of which were hot, which battered down some of the houses in the village, and in other cases lodged in the thatched roofs. The mud appears to have fallen in the form of an exceedingly heavy rain, with occasional large lumps; and page 28 this continued up to 6 a.m. During this downpour, stones of various sizes continued to fall, endangering the lives of those who ventured out of the houses; and, as the stones prove to be of the same scoriaceous nature as those found on top of the mountain, they must have come from there, although the mud, doubtless came from Rotomahana and the fissure in which Rotomakariri Lake was formerly situated. All this time there appears to have been a more or less strong odour of sulphurous and other gases experienced by the people of Wairoa; and Mr. Blythe describes a hot suffocating blast which nearly choked himself, Mr. Lundins, and Miss Haszard, after their escape from the burning house, and which warmed them through—a welcome change from the bitter piercing cold which appears to have prevailed the whole time.

Soon after the commencement of the eruption, and before the fall of the first stones, a great wind rose, which rushed down the valley of the Wairoa towards the eruption, and which branched off by Tikitapu Lake, rushing up the funnel-shaped valley there, prostrating the beautiful forest, and utterly destroying it.

It is noticeable that the people who survived and were nearest to the seat of eruption—viz., those at the Wairoa—failed to hear the loud detonations which reached Auckland and other places: possibly the loud and continuous roar drowned the other reports by interference. These explosions were heard at Hamilton, Cambridge, Coromandel, To Aroha, Taupo, Christchurch, Nelson, Blenheim, Auckland, New Plymouth, Helensville, Whangarei, Waiapu, and Wellington, and in a much less degree at places on the Bay of Plenty Coast.* They sounded like the reports of distant cannon, or, as has been described by a large number of people, like the noise caused by blows on an iron tank. A considerable disturbance of the atmosphere was noticed in Auckland in the form of vibrations of the air. After each report the windows of the houses rattled and shook as much as they would have done from a slight earthquake-shock. The flashes of the electric display also were distinctly seen there, a distance of 1.20 miles in a straight line from Tarawera. It must have been on the grandest scale. The vast cloud appears to have been highly charged with lightning, flashing and darting across and through it, sometimes shooting upwards in long curved streamers, at others following horizontal or downward directions, frequently ending in balls of fire which as often burst into thousands of rocket-like

* It is strange that the reports were not heard at Lichfield, only about forty miles to the west, whilst they were heard distinctly at Waotu, about six miles further off. Mr. Howard Jackson suggests that the waves of sound were deflected by the eastern side of the Patetere Plateau, and so carried over the heads of the people of Lichfield.

page 29 stars. Fireballs fell at the Wairoa and other places. Doubtless the streams of lava reported as having been seen coursing down the sides of Tarawera were some of these slowly rolling along the surface, or appearing to do so from the point of observation. Mr. Blythe describes some of them as moving horizontally along the edge of Lake Tarawera, just under the mountain, in such a manner as to give rise to the belief that they were lights in the boats from Te Ariki. Whilst sheltering in the verandah of Mr. Haszard's house he saw a large ball of fire fall on the roof and slowly roll over to the ground, and there disappear. In all probability Mr. Haszard's house was set on fire either by one of these, or by the lightning, as was also the forest on the north side of Lake Tarawera, which was burning a few days after the eruption in several places.

The immense cloud of ashes and dust which was shot high up into the air, driven first by the south-easterly wind in a westerly course, and then by the south-west wind in a northerly and easterly direction, quenched the bright moonlight and darkened the sky for hours after daylight should have appeared. The Cimmerian darkness was such as "could be felt." Charged with its burden of ash, dust, and sand, it gradually spread from the point of eruption, one edge of it taking a north-westerly direction, the other nearly cast, until it passed out to sea, dropping as it went its load of matter all over an extent of country covering 5,700 square miles of land, the extreme western point of which was on the coast near Tairua, the extreme eastern being at Anaura, a few miles north of Gisborne—points 160 miles apart. All over this area more or less fine ash, dust, sand, or scoria can be found, decreasing in quantity as the focus is left, the extreme edges being so lightly covered that the deposit disappeared with the first rain.

The height to which this dust-laden cloud and its accompanying brilliant electric discharges reached, was enormous. It was clearly seen from Auckland by several people, one of whom, Mr. R. Arthur, of Mount Eden, carefully noted the height of the topmost edge as seen against the profile of a neighbouring hill: the angle of elevation, afterwards measured by Mr. Vickerman, of the Survey Department, gives a height above sea-level of 44,700 feet, or a little over eight miles. Great as this height may appear, it is less than the observed height of the column of steam arising from Krakatoa, as measured by Professor Verbeck in 1883, which was 50,000ft. Archdeacon Williams, at Gisborne, who took some rough observations of the cloud, calculated the height to be six miles.

Mr. Eric C. Gold-Smith, District Surveyor, Tauranga, has collected page 30 the following data from gentlemen living on the coast of the Bay of Plenty as to the times that the first fall of dust and other phenomena occurred. At Tauranga it began to fall about 6 a.m., first lightly, afterwards heavier, and then lightly again, till it ceased finally at noon on the 10th. Depth of deposit, about half an inch. The darkness was so great that no gleam of daylight appeared till 10.30 a.m.; the greatest darkness being from 9.30 to 10.30, from which time it gradually became lighter till 11 a.m., when the sun was first visible. The passage of the cloud was accompanied by a strong sulphurous smell.

At Te Puke, on the evening before the eruption, there was a light east wind, changing to the south about 4 a.m. on the 10th; and at 6 a.m., just at dawn, the first fall of light dry ash was noticed, which, as the south wind freshened to heavy squalls, with rain, turned to mud, with an increase of quantity. By 8 a.m. the dust was falling steadily, but dry, the rain-squalls having ceased. At 12.30 it finally ended. Depth of deposit, 3in. At 6.30 the darkness was intense, with thunder rolling overhead, accompanied by lightning seen at intervals through the dense cloud. It gradually cleared off, till at 1 p.m. the sun was just visible.

At Maketu, the dust began to fall at 4.30 a.m., and the air was full of it at 1.30 p.m. Depth of deposit, 1in. A slight appearance of daylight at 6.50 a.m., but total darkness from 6.55 till 9.45 a.m., and more or less dark till 1.30 p.m. when the sun was first seen. Strong electrical disturbance noticed on the 16th April and 3rd, 5th, 10th, and 14th June. On the 5th June very strong, and lasting from 9 a.m. until 12.10 p.m. The telegraphist, Mr. Benner, who kindly supplies the above, says, "I had never seen anything so continuous as the electrical disturbance on the 5th until the 10th June, when the wires became altogether unworkable from 5.50 a.m. until 9.50, and continued later but not so strongly."

At Whakatane the dust began to fall at 3.30, and at 8 a.m. it was wet like wet sand; the fall ceased about 9.30. Depth of deposit, 3in. The darkness came on (eclipsing the moonlight) at 4 a.m., and it was not light till 10.30. The dark cloud appeared to travel down the Whakatane Valley, its nearer edge flashing with lightning, accompanied by rolls of heavy thunder and a rumbling noise.

At Opotiki, it was pitch-dark till 10.20 a.m., from which time it gradually brightened till noon, when the sun became visible. The dust began to fall at 3.30 a.m., and continued steadily to do so till 10 a.m., and in a lesser degree from that time till noon, when it ceased. Depth of deposit, 1½in. The cloud as it approached was seen page 31 to be illuminated with chain and forked lightning, and many balls of fire seemed to fly upwards from base to top.

At Orete Point daylight broke as usual, but it became quite dark again at 8 a.m., and remained so till 11 a.m. Depth of deposit, l in.

At Waiapu, near the East Cape, Mr. White states that it was quite dark till 11 a.m., and that the dust fell to a depth of l½in., most of which has since been washed away by the rains. It was so dark at 10 a.m. that a candle could not be seen at 10ft. distance through the falling dust.

At Motiti Island, Mr. Douglas states that it was daylight as usual, but that shortly after 7 the black cloud came over and caused it to be pitch-dark till 11 a.m., the lightning flashing and the thunder rolling through it the whole time. Depth of deposit, 1/8in.

At Oropi, (just on the edge of the deposit,) the dust first fell at 8 a.m., softly at first, quickly at 9 a.m. and slightly moist, ceased at 10 a.m. Depth of deposit, 3in. At 9 darkness set in; 9.15, total darkness; 10 a.m., bright again. In addition to the ordinary thunder there seemed to be constant explosions within the cloud, with continuous zigzag lightning, and for three hours intense cold.

At Mayor and Alderman Islands the dust fell to a depth of¼in.

At Rotorua the dust began to fall at 4 a.m. It was quite dark at 7.30, and again at 9 a.m. Depth of deposit in the township,¼in.

The earthquakes accompanying the eruption are described as severe; and, no doubt, to those who experienced them they appeared so, but, judging from the effects at Rotorua and other places, they cannot he properly so called—no light articles such as bottles or vases on shelves appear to have been thrown down, nor can these earthquakes be compared in point of severity with those experienced in the neighbourhood of Cook Strait in 1813; 16th, 17th, 19th October, 1848; or that of the 23rd January, 1855, which elevated the coast near Wellington and formed the great fissures at Wairau, in the Southern Island. They were evidently much more severe in the immediate neighbourhood of the eruption, and especially in the southerly continuation of the great fissure towards the Paeroa Mountain; for here we find the ground cracked and fissured to a considerable extent, but in all eases these cracks follow the lines of former ones, or lines of subsidence (faults, in fact), as will be shown later on. Still, notwithstanding their lightness, they were felt over a considerable area of country, extending in several cases outside the zone of volcanic rocks, and were continued in many parts for six weeks after the eruption.

The following notes respecting them have been collected:—

Tauranga.—The first shock felt at 2 a.m. on the 10th, the page 32 heaviest at 4.30 a.m., and constant light shocks and tremors were felt up to the 25th July.

Opotiki.—First shock at 2 a.m., subsequently frequent slight shocks.

Te Puke.—First shock felt at 1.30 a.m; two severe shocks, one at 4.30, the other at 9 a.m., with continuous slight shocks and tremors for two days.

Oropi.—First shock at 2.30 a.m., continued motion every ten minutes up to 6 a.m. It is worthy of note that this part of the district seems to have been more subject to continued heavy shocks up to the end of July than any other part, excepting only the immediate vicinity of the eruption.

Whakatane.—First shock noticed at 3 a.m., with continuous sub-sequent shocks, the most severe being those at 3 a.m. and at 5 a.m.

Maketu.—First shock felt at 2.30 a.m., the most severe at 4.32 a.m., and the period during which the heaviest and most frequent shocks were felt was from 4.32 a.m. to 6.30 a.m., and a rather heavy one at 8 a.m.

Matata.—Shortly after midnight; continued and severe shocks subsequently continued up to the 19th June.

Rotorua.—Slight rumbling and shake at 1 a.m., heavy shock at 2.10 a.m. and at 4.30 a.m., and since that date continued up to the end of July, when they ceased.

The earthquakes were also felt at Te Aroha, Waiorongomai, Cambridge, Lichfield, Waiapu, Taupo, and, no doubt, at numerous other places; but those named seem roughly to mark the western limit of them. At Galatea they were continuous and heavy for some days, but eastwards of that we have no record except at Waiapu*, the country being inhabited solely by Maoris.

In the immediate vicinity of the eruption, at the survey camp, Pareheru, they were felt daily from the 25th July up to the 8th August, when they ceased, the cessation being accompanied by a decrease in the activity of the various points of eruption.

From early in the morning of the 10th, when the great cloud of dust and ashes descended, covering the country for miles round the seat of eruption, nothing was visible of the mountains until the morning of the 13th. Everywhere a great cloud of smoke and vapour, lying close to the surface, hid the face of the country from those anywhere in the neighbourhood to the west. Of the five or six

* The heaviest shock of earthquake over felt by the European inhabitants of the district occurred in the first week in September (the 3rd), when also a heavy shock was felt in the neighbourhood of Cook Strait.

page 33 Europeans living at Galatea, some twenty-five miles to the east, two—Mrs. J. C. Blythe, and, subsequently, Mr. H. Burt—attempted on the 12th to get through to Rotorua by the usual track, but had to turn back, as they found the road cut off by deep deposits of ashes. Mr. Burt subsequently reached Rotorua on the night of the 12th by a long detour, and he brought the news that the eruption had extended some few miles south-west of Rotomahana. The first sight of Ruawahia and Tarawera Mountains, on the morning of the 13th, at once disclosed to those who were acquainted with their shapes that a great change had taken place. The nearly level plateau-like top had become higher, and was broken up into a series of little peaks, from near which columns of smoke and vapour arose into the air. But the eruption had evidently ceased as far as the ejection of solid matter was concerned. A vast column of vapour arose from Rotomahana: for at least 15,000ft. in height, and the roar it made was to be heard continuously, with sharper detonations occasionally, for a distance of sixteen or eighteen miles.

Subsequent observations prove that nothing was ejected from Wahanga, Ruawahia, and Tarawera but black and red scoria; and, as none of this fell after 6 a.m. on the 10th, it follows that the eruption was practically all over in six hours, as far as those mountains are concerned. But with respect to Rotomahana it is not so clear. Evidently the mud which covers the country from Rotorua to that place came from there, and this ceased in places where observations could be made by 6 a.m.; but whether the sand and ashes around Rotomahana and the southern group of craters were all ejected within that short space is doubtful. Most probably the eruption was in that locality of longer continuance. It had, however, quite ceased on any scale by the morning of the 13th, though paroxysmal outbursts from a large number of vents continued for some time longer—indeed, up to the 6th August, when the Black crater was in eruption for a short time.

When we come to consider the changes that have taken place in the face of the country, and the depth and amount of solid matter removed by the action of water flashing into steam, it is marvellous that so much energy could have been compressed into so short a space of time. Obviously the magnitude of the eruption must not be gauged by the time it lasted. It has already been stated that more or less dust, sand, or lapilli is to be found over an area of 5,700 square miles; but the country affected, in so far as vegetation has been injured and farming or grazing operations interfered with, is of much less extent, amounting to about 1,500 square miles. Even in page 34 this area, fortunately, the country brought under settlement is not very great. The farms along the coast-line of the Bay of Plenty, extending from Tauranga to Opotiki, have suffered considerably, and great loss has been entailed by the destruction of the grasses, necessitating in many instances the removal of the cattle to other districts. But, generally speaking, the country is by no means permanently affected. Already the grasses are forcing their way through the covering of dust, whilst a general opinion seems to prevail that it will eventually benefit the light soils of the district by becoming incorporated with it.

There are some very noticeable facts in connection with the distribution of the various kinds of ejecta, which can only be explained by the supposition that some of them reaheed higher strata of the air than others, and there met with currents differing in direction from the lower ones. The first outbreak, as has been said, consisted of molten scoria and lapilli derived from Wahanga, Ruawahia, and Tarawera. This seems to have been distributed with a fairly constant radius from a direction south-east from those mountains, round by the south-west and north; whilst from a direction east of north the lapilli seems to have been ejected with greater force, and so has reached a greater distance. From Galatea, nearly on the southern edge of the deposit, northwards to Te Teko and beyond it, down the Whakatane Valley, scarcely anything but fine black scoria is found, and as the mountains are approached the depth of the deposit and size of the fragments increase until on top of the mountains molten masses weighing several tons can be found. To the south, and far beyond the limit of the subsequent covering of sand and dust, the fine lapilli is found thinly scattered, whilst to the west the sand and mud have distanced the lapilli.

The mud (or, rather, wet sand), which lies westward from Rotomahana, and extends to Rotorua and thence northwards towards the coast, is not found far east of the Tarawera River. The source of this mud was undoubtedly Rotomahana; for, though Dr. Hector is probably correct in attributing, it partly to the condensation of the steam-cloud charged with dust as it met the cold south-west wind, we have only to reflect on the vast amount of water and mud which occupied the former basin of Rotomahana, and the great area of loosely-formed rocks which have there been blown out, to see that this supply is about equal to the covering laid over the country where it is found. This mud commences within a mile of the former lake, and, as there is abundant evidence that subsequent to its ejection the crater threw out dry sand and dust, doubtless in the immediate vicinity page 35 of the crater the mud has been covered over and obliterated. South and south-west of Rotomahana no mud is found, the deposit there consisting of dust and sand, and as the southern edge is approached this becomes an impalpable white powder, feeling and looking more like flour of a somewhat dirty colour than anything else. It has been ejected, without doubt, from the southern group of craters. Scattered all through the sands and dust, however, and at various levels, the fine lapilli can be seen, showing that the outburst of Tarawera and its neighbours continued on a diminished scale nearly, if not quite, as long as the other craters; but in mentioning this an exception must probably be made with respect to the flour-like dust on the southern edge—an exception which will be referred to later on. Reference to the other ejcctamenta will find a more fitting place when describing the several craters and points of eruption in detail.