THE EARTHQUAKES.

Star (Christchurch), Issue 332, 7 June 1869, Page 2

THE EARTHQUAKES.

.» The following particulars have been kindly furnished by Dr Haast : — An earthquake, however violent it may be, is of such a transient nature, that it is very important, for the furtherance of physical science, to collect the information of all the phenomena observed before, during, and after its occurrence at the earliest date possible. May I therefore be allowed to send you the following notes, in 'the hope that other observers will favour us with their experience ? The morning of the sth of June was remarkably clear and beautiful, with a rising barometer, when, at 8.30 seconds a.m., a considerable earthquake shock, the most severe I ever felt in Canterbury, visited Christchurch and its neighbourhood. This shock, coming from the south, lasted about 3 to 4 seconds ; it was succeeded, after a short interval of 2 to 3 seconds' repose, by a slight tremor of very short duration. Another slight vibration, of a similar nature, was experienced at 7.16 minutes p.m. I have been told that towards 12.30 p.m., a similar feeble shock was experienced, which, however, I did not observe, although at that time I was sitting in my office and writing. Erom the observations I was able to make, the principal and first shock had, aa near as possible, a magnetic south and north direction, or from south 15 west to north 15 east. This first portion of the vibration in question was immediately followed by another, which came from the east, or at right angles to the first. As this second portion of the vibratory jar has also done some harm in a few stone buildings and chimneys, many persons in Christchurch therefore believe that this was the principal direction, but I think 1 shall be able to shew that the earthquake came from the south, and that the other direction was a secondary one. I shall confine myself in this communication to my experience in my own house and its neighbourhood only. As far as I could observe, no hollow subterranean rumbling sound preceeded or accompanied the earthquake, although in the latter case it may easily have been drowned by the creaking of the timber, the ringing of the house bells, and the falling and breaking of numerous objects. Mr George Dunnage told me, however, that he heard distinctly the low subterranean sound in his house at the river Styx, near the Chriatchurch and Kaiapoi road. As before observed, the first movement was from the south to the north. The ground seemed to rise obliquely, and then to return immediately with a wave-like motion. During the first part of the shock, which seemed to me by far the most severe of the whole earthquake vibrations, the greatest damage was done, as most of the objects were then thrown down. I stated before that the direction of the earthquake had been as near as possible S 15 W. to N. 15 E., and your readers would doubtless like to know how I obtained that result. As bodies from their inertia fall usually backwards or in the direction from which the shock comes, it is evident that the position of such bodies after their fall will give us that direction. It is on this rule that the seismometer has been constructed, a very useful instrument to measure the direotion and intensity of earthquake vibrations. Although I had no such instrument in my house, a milkcan, filled nearly to the brim, acted as such in aa excellent manner. The milk had distinctly run from N. 15 E. to S. 15 W. over the table in an unbroken stream, and only a few scattered drops were found in the opposite direction. Again, on the opposite side of the same wall, and in different rooms, are two mantelpieces on which some vases were standing. In one room, where the wall in question is to the west, none of the vases were broken, having had some support from that wall

when the great shock reached them ; whilst on the other, or opposite one, having the wall to the east, a vase of nearly the same size, and of the same material, was thrown down, the pieces also lying in the same direction as the milk had flowed. Behind my house, in a street leading from Stanmore road to Armagh street, three brick chimneys were thrown down, the principal portion of which I found also on the same line, a few bricks only having fallen on a line opposite to it. Several objects which, during the first shock, had remained standing, fell afterwards, when the vibration from the east took place. As before observed, it is this last shock which must have caused the principal damage to the stone buildings. Those component parts of stone buildings most liable to be displaced, not having settled down from the first movement, were now thrown in a different direction, from which they were sometimes unable to regain their former position. It is also this vibration which turned many objects partially round on our tables and shelves, and gave a twist to stones in buildings and chimneys, so that, at first sight, it might suggest a rotatory vibration. Mr Richard Fereday, who was, during the earthquake, in his garden, and who saw and heard distinctly its effects before it reached him, will, I hope, publish his experience, as confirmatory of my own observations. It is almost needless for me to observe that, according to the nature of the ground, great changes in the duration and intensity of an earthquake usually take place, and that, in this instance, amongst other secondary causes, the direction of the bed of or vicinity to the river Avon may have had a material influence in different parts in Christchurch. It was with considerable anxiety that I started this morning to town, fearing that considerable damage might have been done to property in Christchurch, and also that the telegraph might bring us accounts of far greater destruction done in other parts of New Zealand It was with a feeling of great satisfaction that I observed how comparatively little damage had been occasioned in Christchurch, and that, with the exception of Lyttelton, this shock had not been felt anywhere else in New Zealand. : That tho earthquake was not felt so severely in Lyttelton as on the Plains may be accounted for by the fact that the former is built upon volcanic rocks, which have a far greater elasticity than sand and gravel, on which Christchurch stands. It thus appears that this earthquake is simply the dynamic effect of some local abyssological disturbance in or near our neighbourhood, such as happens all over the globe by changes in the crust of the earth, and generally at a very great depth below us. I think there is, therefore, no cause for the anxiety expressed to me by several of my fellow-citizens, that this earthquake might be the beginning of a Beries of still more vehement disturbances by which we are to be visited, although it is possible that a few minor ones may still follow in the course of the next few days. Others believe that the origin of this earthquake is connected in some way with Banks Peninsula, an extinct voloanic system of considerable extent, which opinion in this instance I consider equally erroneous. I may, however, state that the primary direction of that disturbance closely corresponds to that longitudinal volcanic region which from the antarctic volcanoes Erebus and Terror stretches across the intermediate islands, also of volcanic origin.to New Zealand, and on which line Banks Peninsula is situated. These notes are necessarily imperfect, but I " trust that the inhabitants of the province who take an interest in physical science will favour us with their own observations. And I should consider it a great favour if gentlemen living in the country would send you or me an account of what they experienced, so as to be able to prepare a connected report of the whole phenomenon, comprising its extent, direction, and intensity. Your obedient servant, JULIUS HA AST.

"We learn from Kaiapoi that the most severe shock within the memory of the oldest 7 inhabitant was felt at 8 a.m., on Saturday. 1 A correspondent writing from Ohinitahi says: — " I have to report the occurrence of a rather sharp shock of earthquake this morning, at about six minutes past eight. It lasted several seconds, and appeared to pass from east to west." A correspondent writing from Halswell reports a severe shock at about 7.47 a.m., giving the direction as from south-east to north-west. Our Akaroa correspondent reports : — A severe shock was felt in Akaroa on Saturday morning, the sth inst., at near 8 o'clock. It appeared almost like two distinct shocks, and lasted some seconds, the oscillatory motion being very perceptible. Our Wellington correspondent reports by telegraph yesterday that there was a slight shock at Featherston, on Saturday night, and one at Wellington yesterday morning, at 7.12.