SEISMOLOGICAL ENGINEERING

Press, Volume LXXXIX, Issue 27047, 23 May 1953, Page 9

SEISMOLOGICAL ENGINEERING

RESEARCH BY D.S.I.R. INFORMATION TO BENEFIT BUILDING CODE The Department of Scientific and Industrial Research has for some years been carrying cut research in engineering seismology, both at the Seismological Observatory and the Dominion Physical Laboratory. It is hoped that the investigations will give the structural engineer and the architect information that will enable them to design better earthquakeresistant structures, and so minimise the loss of life and damage to property from earthquakes.

A Report from the department says that engineering seismology is important in New Zealand because the Dominion lies within one of the world’s earthquake zones. It deals with the effects of earthquakes on manmade structures—buildings, bridges, dams and chimneys. The first step in improving the New Zealand Building Code is to find out more about the stronger earthquakes in the country, says the report. The ordinary observatory seismograph, which is used for recording weak and distant earthquakes, is not suitable for this purpose. A special instrument called a strong-motioned seismograph, designed to record the heaviest shocks, is used for recording these earthquakes.

One of these instruments wag imported from the United States and installed at the Seismological Observatory, Wellington, towards the end of 1948, and since then has recorded the stronger earthquakes that have occurred. There havd been six of these, and from their records useful information has been obtained. Information is also required about the characteristics of strong earthquakes in other parts of New Zealand, and for this purpose the Dominion Physical Laboratory is designing and building six strong-motion seismographs, which will be located in Hawkes Bay, Wairarapa, Wellington (on reclaimed land), Hutt Valley, Buller and North Canterbury. A cheap and simple seismograph that will give limited but still useful information is also being designed. It is hoped to make a larger number of these and locate them so as to fill in the gaps between the more expensive instruments.

Buildings can be set into vibration by the wind, traffic, or earthquakes, and the period of vibration of a building,—the time taken to complete one swing back and forth—is of importance when estimating its resistance to an earthquake. The Dominion Physical Laboratory has designed and built instruments which will record the smallest movement of a building on a moving chart so that its period of vibration can be found. A machine called a building vibrator has also been built. This can be used to subject a building to a small scale earthquake so that its response can be studied and recorded.