QUAKE AFTERMATH

Dominion, Volume 37, Issue 227, 22 June 1944, Page 4

QUAKE AFTERMATH

Damaged Buildings That “Work” HOW SMALL CRACKS GROW LARGER Recently at the reopening of the Regent Theatre ' after being closed for earthquake repairs for IS months, the then mayor of Wellington, Mr. T. C. A. Hislop, mentioned that damage done by the earthquakes of 1942 had already cost Wellington property-owners about £1,000,060. What it will ultimately cost no one knows, for there is enough work to continue, not only for the rest of tins year, but well into tbe next, if the repairs deemed necessary by experts are to be carried out. Damage to buildings by earthquake is not always visible. The eye cannot detect, on a casual look round, the extent to which any buildings may have been damaged, us the evidences are often concealed within the 'structure itselt, and sometimes only revealed by accident or diligent exploration. Officers of the city corporation who have had to make a careful study of earthquake damage to city buildings have collected a wealth ot information. This shows that builflings, when once partially damaged by earthwrench, do not remain static; they are inclined to “work," which means that the initial damage develops little by little, and becomes more apparent to the eye as time goes ou. “The adopted technique ol belting damaged buildings with bands of steel reinforced concrete, is not put forward as a preventive of all future earthquake damage,” said one expert. “No one living can guarantee freedom from earthquake damage to any building, no matter what the nature and strength of the structure. The reduction of top-hamper weight and waist and parapet belting, with stabilizing vertical piers, can oniy, at the best, make the building less vulnerable to damage from the lesser disturbances to which the country may be said to be subject. “It is known that New Zealand is one of the oscillating areas of land which ring the great basin of the Pacific Ocean. Oscillation (or tiny earthquakes) may be said to be of almost daily occurrence. People may not feel them, it is true, but none the less they do occur; and the combined effect of these tiny tremors, as well as slight earthquakes, are factors that account for the "working” of main or cross walls in buildings already damaged by a severe disturbance, similar in degree to those experienced in Wellington in June and August of 1942. “Observation on the part of the corporation’s officers indicates beyond all doubt that the apparent damage don? by a first shock may only be the beginning of more serious (and more costly) damage. There- is one instance which substantiates this. After the 1942 earthquakes an inspector was called on to examine for damage a very large central retail departmental store. No trouble was experienced in defining the nature and extent of the damage to the main back wall, which was attended to in the usual way. Though a careful inspection of the opposite wall (facing the main street) had been made at the same time, nothing was then visible that could be interpreted as signs of damage, yet a year Inter, when the building was again inspected, such signs appeared, an obvious indication that the structure was ‘working.’ "Another instance was in connexion with a large bulk store. Visible damage suggested further cracks in certain positions, which close search did not then reveal. Shortly after the commencement of development work, however, the other anticipated cracks became visible. The change, or development, in this case, may have been due to the vibration of pneumatic drills used in the demolition job. In still another case, where 50 people or more are still daily employed, there are ‘a cloud of witnesses’ to the damage which has been done to the structure; so bad that the outer walls have little relation to the cross walls, each of which has become an independent unit Another severe shake would be a real danger to this building.”