BULLER SHOCK COMPARED

Hokitika Guardian, 26 February 1931, Page 2

BULLER SHOCK COMPARED

NEED FOR WISE BUILDING. MK H. F. BAIRD'S OBSERVATIONS An interesting comparison of the Hawke,s Bay and .Murchison earthquakes, together with much good advice to builders, was given by Mill. F. Baird, chief assistant at the Christchurch Magnetic Observatory on his return this week Irom Napier. “Considering the cabled reports oi seismologists together with the invetigations L have made both alter the Buller and after the Hawkes Bay earthquakes,” sad Mr Baird, “it seems to me that at the wrost phase the Hawkes Bay shake was shorter and more violent than the other. However, the Buller shake was much more prolonged and caused much more widely spread damage. Possibly the Hnwkes Bay shock originated at a greater depth. Observations made it appear that the centre of the worst disturbance ay seaward slightly to the north of Napier. The absence of mountainous country made it difficult to compare the earthquake with that at Murchison, hut records indicated that, although shorter, it was more severe At Murchison there was an uplift of 15 feet, while at Napier the greatest uplift that hail been established was seven feet. From personal impression.of the effect of different kinds of earthquake waves, he considered that most of the after-shocks came from a distance of 35 miles from Hastings. LESSONS IX BUILDING. “That wise building practice is of paramount impor'am ;■ io w /.■ a land is the point to which \ ;iUie most emphasis in an address on ’ H.■ Muller earthquake,” added Mr Baird. “My recent visit to Hawkes May lias convinced me more than ever on this point. One of the worthy objects of the Seismological Society of America comes to my mind. It is embodied in a statement emphasising and understanding of the facts that earthquakes are dangerous chiefly because we do not take adequate precautions against their effect where it is possible to ensure ourselves against damage by proper studies of their geographic distribution historical sequence, activities, and effect on buildings." .Mr Baird emphasised the need for adequate building regulations in areas likely to be affected by earthquakes. From his observations, he was sure that with fcrro-concrete buildings the risk of losing life was nil. The damage to brick buildings spoke for itself. WEAKNESSES OF ARCHITECTURE “Excessive window space, porches, and such other sacrifices to strength were much too prominent in the ground floors of many buildings. Unsupported, heavy gables were also too often to be seen. Poorly-tied roof trusses had frequently collapsed, while even ip wooden houses badly braced buildings had often battered one part against the other until the whole had disintegrated and almost collapsed.” Freeh, nil Austrian geologist, had suggested that the Byzantine stvlo o' church architecture was developed partly in relation to the pronounced seismicity of the eastern Mediterranean. In particular, the use of lateral half domes buttressing a central dome was an effective solution to the problem of stability in land subject to shook.

RECURRENCE UNLIKELY

Of earthquakes generally, Mr Baird said that it was well to remember that fortunately New Zealand was less disurbed seismically than were Japan or •south Italy. History showed that the possibility of a devastating earthquake recurring in identical places within a period of a few centuries was very remote. One of the few instances where such a recurrence lias been known was on the Bozo Peninsula, Japan where one disastrous shock occurred in 1703, and another in 1923. The South of Italy was another area where shocks were liable to recur after long intervals.

Mr Baird left for Wellington on the evening of the earthquake. Most of the survey was made by air. and he stressed the import:. ■ ■ r ' lnable and reliable information b n had re-

ceived from Squadron-Lc *> : i.uTf and other pilots at Hastings, it. > ev leaving Hastings, he established a .Tagger seismograph at the house of Mr Henry Dedenne, who had both the capability and the enthusiasm to look after the instrument.