The late Earthquake, and its Bearings on the Architecture of Wellington.

By W. M. Maskell, F.R.M.S.

[A Paper read before the Wellington Philosophical Society, Sept. 12th, 1888.]

Until the present month it is more than 30 years since an earthquake violent enough to be destructive has occurred in New Zealand. Many shocks there have been in almost every year, and once or twice these have been sufficiently strong to overturn chimneys, or to crack buildings, but they cannot well be termed "destructive" in the ordinary sense. When in, I think, 1872 the Christchurch Town Hall was badly shaken, and several other buildings damaged, much of the mischief seems to have been due to defect of construction or workmanship, and the knocking out of a stone from the Christchurch Cathedral spire about 1882 might have been ascribed, perhaps, to the newness of the work, which had then not been long finished. But the numerous disturbances of the earth's crust which have been felt since 1854 in New Zealand have been in the main so slight as to induce almost a feeling of security amongst the people, the prevalent idea seeming to be that the forces producing great earthquakes are of less violence than formerly. There is, however, absolutely no spot on the face of the earth of which it can be said that an earthquake will not occur in it; and when it remembered that the most violent of all our New Zealand shakes happened in the neighbourhood of Wellington only about 30 years ago, and that a large part of the Te are District in this city could probably not have been built over if that convulsion had not raised it several feet, one is inclined to wonder sometimes at the apathetic coolness of the inhabitants, and especially of their professsonal and municipal authorities. The earthquake of September 1, 1888, appears to have been most heavily felt in the districts ranging from Nelson to Hokitika and Christchurch, a roughly triangular area, mostly on the western side of the main range, and, as far as I know, not supposed to be peculiarly subject to such convulsions. It is far from my intention to dwell at all upon the purely scientific aspect of this event. Professing only the very slightest acquaintance with geology, I leave it altogether to the geologists to say whether that district shows signs of previous disturbance or not. We shall hear all about the scientific theories in due time. My object to-night is to draw attention to some practical points likely to touch nearly the interests of the inhabitants of Wellington. I have said that the comparative immunity which this city has enjoyed since 1854 from violent earthquakes appears to have produced a feeling—not actually expressed, probably, by anybody, yet page 4 tacitly adhered to—that we are not likely to be again troubled so much as on that occasion. This opinion may be right or wrong in actual future fact, yet there is nothing whatever to justify it at present in the slightest degree. It is, therefore, not altogether a consoling thought that the Municipality of Wellington, who might be supposed to take into consideration everything tending to the interests of the people, seem to have adopted this idea as if it were founded on a solid basis. Procuring a few days ago a copy of the Building By-laws passed by the Wellington City Council in February, 1888, and now in force in this town, I carefully read it through, and was somewhat surprised to find that there is not, with one small exception, a word to indicate that any danger to life or property is to be feared from earthquakes. The City Council seem to have had a thorough dread of fires, but none of earthquakes. Curiously, also, the exception to which I have referred seems to be nothing more than a dead letter. Clause 19 of the by-law provides that "every chimney . . . must be built from its foundation to the top thereof without any corbelling over whereby any of the brickwork, stone, or concrete of such chimney shall overhang any lower part thereof." This may, in view of earthquakes, be a useful provision; but I doubt whether there is one chimney in a thousand in all the town which is built in compliance with it. In clause 23, it is stated that the City Surveyor shall have power to pull down chimneys built previously to the passing of the by-law if they "cause reasonable danger of fire," from being built contrary to the provisions of the law. But no mention is made of earthquakes. Similarly, in clause 36, all sorts of "architectural projections" are permitted on the outside of buildings, if "approved by the City Surveyor," provided only that they are placed high enough above the street. Perhaps the effect of stones falling from a height are considered in city by-laws to be only trivial matters. Taking the whole of these provisions into consideration, it would seem that the Corporation of Wellington, when drawing them up, had made up its mind that for the future the town would never suffer from convulsions of nature similar to those which have occurred in past times. But it may perhaps be reasonably thought that in matters of this kind a number of municipal representatives, necessarily chosen for quite different reasons than scientific knowledge, must rely upon professional advice, and that the people of Wellington must place confidence in the ability and complete thoughtfulness of the architects who design their buildings. I make not the least doubt that every architect in this Colony is in the fullest degree capable of providing, as far as human skill can provide, against accidents of all kinds; and it is with the very greatest diffidence that any layman should venture to put forward opinions as to the proceedings of professional men. Yet it is permissible for even a layman sometimes to "want to know, you know;" and there are features in some of our Wellington buildings which to an imperfectly instructed mind seem to be not altogether satisfactory. I must premise to what follows, that I am quite well aware that in matters connected with earthquakes there is absolutely no certitude available at the present day, and that the vagaries of these phenomena are constantly upsetting all seismological theories. Yet on the authority of Professor Milne, of Japan, probably the highest on the subject now living, I find that the experience of many countries and many observers has produced certain data, which are probably, as far as we know, correct. Amongst others it would seem that the following ought to be kept in view by page 5 anybody who builds in stone or brick in an "earthquake country" :—"1. So arrange the openings in a wall that for horizontal stresses the wall shall be of equal strength for all sections at right angles." (The meaning of this I take to be, that it is better in buildings of several storeys not to have the windows all arranged in regular vertical lines. A quincuncial arrangement has been suggested as preferable; but I do not know any instance of its application.) "2. Avoid heavy-topped roofs and chimneys. 3. Let archways curve into their abutments." (Archways here seem to include window openings.) "4. Place lintels over flat arches of brick or stone." Seemingly Professor Milne's suggestion is that these lintels should be of iron or timber. "Vaults and keystone arches," he says, "are more perilous than common wood lintels." In addition to the foregoing, I find the following two points suggested :—Height is dangerous: "To build high houses would be to erect structures for the first earthquake to make sport of;" and again, "When the inhabitants of South America saw the Spaniards building tall houses, they told them they were building their own sepulchres." On the other hand, although there seems to be nothing positively to be asserted as to foundations and solidity, it would appear that heavy solid buildings on deep foundations have less safety than light buildings on loose foundations. I do not venture to express an opinion on this point; yet two illustrations from Christchurch seem as if they confirmed this view. One is a very large warehouse of brick, with high thin walls, apparently without any support or buttresses;—and I have heard people remark that some day it would even be blown over, yet I understand that the late earthquake has not damaged it in the least. The other, built on shallow foundations, and seemingly, also, by no means strong in its construction, has also escaped injury, somewhat to the surprise of Christchurch friends of mine, who have remarked on it to me lately. As regards the foregoing points, and the architecture of Wellington, I have taken opportunities of looking at some of the brick and stone edifices in this town, with the result of finding that almost all these points appear to be neglected in at least the greater part of them. For example, in the Post Office, a building which looks as if designed to show how many windows could be arranged in the least space, the openings are placed in numerous vertical rows, their arches springing sharply from their abutments; and there is a heavy cornice running on the top of the somewhat thin walls. The large building of the National Mutual Insurance Company has also a heavy cornice, numbers of external ornamental projections, windows in vertical rows and with arches not curved to the abutments. A building now in course of erection near the wharf has the brick partitions between the windows seemingly designed only to resist vertical pressure, and with little strength horizontally. The stupendous ugliness of the new Government Printing Office is such that perhaps even an earthquake might disdain to touch it; here, again, are vertical rows of windows with sharp-cornered arches, and a heavy pediment on each side. I understand also that this is a heavy, solid building, standing on very deep and strong foundations. Messrs. Harcourt's warehouse has the usual kind of windows, and would seem to the uninstructed eye to be dangerously lofty. In street buildings, the openings, mostly very large on the ground floors for shop windows, have above them several others, generally so arranged as to give a weak appearance to the front. And in many cases imitation vases, globes, groups of figures, and page 6 other ornamental devices are placed along the edges of the roofs; these are probably, in most cases, not very solid or heavy, yet they are equally probably harder than the skull of any person they might fall upon. I observe, by the way, that in the Supreme Court these ornaments take the shape of a shell; emblematical, doubtless, of the result to a suitor when the lawyers have done with him. It should be recollected that in cases where, as in the Post Office, a building is nearly all windows and openings, the iron rods and bands used to tie brickwork together cannot possibly run continuously in the external walls. On the whole, an inspection of the brick and stone buildings in the City of Wellington leads the lay mind rather to the impression that architects, at least up to the present, have laid less stress upon safety from earthquakes than on their ideas of artistic effect. Heavy cornices, topping walls only a few inches thick, with these walls reduced in strength against at least horizontal vibrations by numerous vertical rows of openings, may be ornamental, but it would be satisfactory to know that they are equally secure. I have spoken here chiefly of the walls of brick and stone. But there are also the chimneys to be considered; and it is a significant fact that in one of the telegrams from Christchurch it is stated that in the Gloucester-street School the chimneys, topped with heavy stone, were hurled to the ground by the shake last week. But this matter of chimneys interests not only the dwellers in brick houses, but also those in wooden houses. For there is one thing clearly set forth in past experience of earthquakes—that as wooden houses swing at different intervals from those of their brick chimneys, if these last are in contact with the timbers of the house they are very liable to be simply knocked down. Yet probably there is not one house in a thousand in Wellington where the chimney is not built closely touching the wood-work of the roof. These are some of the ideas suggested by the late earthquake. I am well aware of the old adage, "Ne sutor ultra crepidam," and professional dignity may be shocked at the notion that a mere outsider should venture to express an opinion. In the face of past history, scientific pundits may demonstrate quite to their own satisfaction that a destructive shako is not at all likely to occur in New Zealand, just as some people can show to a moral certainty that the world will come to an end in some particular year. And it is always easy to remark that anybody who hints that all is not as it should be is an alarmist, or possibly an ass. Still it does seem not quite satisfactory that the By-laws of the Wellington Corporation should contain no kind of provision against earthquakes, and that a glance at the buildings in our streets should show that the points mentioned by high authority as desirable should not have been taken into consideration. Those who believe that the era of destructive earthquakes has for Wellington passed away may be quite right. It is also on the cards that they may be quite wrong. On the latter supposition, I trust that no member of this Society may be during a severe shock in some of our brick or stone buildings—say for example, the Post Office. It is to be regretted that the City Council, whilst making it compulsory to build in brick or stone in our busiest streets, did not stop to think that there may be other dangers than fire.

The paper, which was illustrated by diagrams, gave rise to an interesting discussion, the general feeling being much in accord with Mr. Maskell's views, and a vote of thanks was unanimously passed to Mr. Maskell.—New Zealand Times, Sept. 13, 1888.