EARTHQUAKE RISKS

Wairarapa Times-Age, 27 April 1943, Page 4

EARTHQUAKE RISKS

RECONSTRUCTION ADVOCATED TO REMOVE POTENTIAL DANGER. ARCHITECT'S RECOMMENDATIONS A nation-wide scheme of reconstruction, to lessen the potential danger from earthquakes in the Dominion, has been formulated by the New Zealand Institute of Architects. The proposals, which, it is suggested, could be used as part of post-war rehabilitation, call for the definition of earthquake danger zones, and a full survey of all buildings within these zones. “The two severe earthquakes in June and August last, followed by one of less but still severe intensity on December 2 in the Wellington Province, have served once again to bring to the foreground of most people’s thoughts the potential menace of collapsing structures,” states the report prepared by the institute which incorporates the proposals. “If these had occurred at a busy hour on a week day, the death roll in Masterton alone would have been high, and if the epicentre had been at Wellinton the death, roll would have been correspondingly higher. Furthermore, when we consider that the earthquakes of June and August had an acceleration of the order* of force 8 on the Rossi-Forel scale, and that a shake such as Napier experienced in 1931 would be 10 times as destructive, it is easy to conceive the damage that would be wrought in the city of Wellington on a busy shopping night. “The number of earthquakes of destructive intensity which have occurred in New Zealand in the last 100 years is considerably greater than has been generally recognised. But a comparison with statistics from other highly seismic countries reveals the fact that a large proportion of the New Zealand destructive earthquakes are of such an intensity that excessive damage may confidently be avoided only by careful attention to sound methods of building construction throughout the whole country.

BUILDING SCHEME. The report contends that in view of this, the Government should give immediate attention to the whole question, particularly with regard to “the existence of a vast majority of buildings which are unable to resist heavy earthquake shock.” The following action, it is recommended, should be taken: —

(1) That the extent of the earthquake danger zone be defined. (2) That a full and comprehensive survey be made of all buildings within these- zones and particularly those of brick construction.

(3) That all buildings within the danger zones be classified as follows: — (a) Buildings erected in compliance with any recognised earthquake code. (b) Buildings of unit brick construction with wooden floores, no reinforced concrete wall bands, inadequate cross wall bracing, and poorly constructed. (c) Buildings whose construction places them between the limits of classes (a) and (b). (4) That consideration be given to these classifications on the following lines:—Class (a) buildings should remain; class (b) buildings should be demolished; and class (c) buildings should be inspected and either demolished, strengthened, or allowed to remain; the demolition of class (b) buildings to being with those buildings lining the main thoroughfare. (5) That a rebuilding scheme be prepared to replace demolished buildings for all. cities and towns within these zones. ■ (6) That such rebuilding schemes be based on the soundest town planning, engineering and architectural principles. (7) That such schemes should form part of the post-war national rehabilitation.

_(8) It is envisaged that the scheme should be expansive as well as progressive in its application. That is to say, that the buildings forming the greatest menace near the centre of the most seismically active zone would be the first to be strengthened or demolished. Those forming a lesser menace in the same area would next be dealt with, while those dangerous buildings in the next less seismically active zone would be treated, and so on until all dangerous zones had been dealt with. (9) That a technical committe be engaged to consider the whole question which these proposals open up.

DRASTIC ACTION SUGGESTED The institute recommended that the proposed technical committee should be composed of a representative from each of the following:—The Public Works Department, the Housing Department, the Treasury, the Department of Scientific and Industrial Research, the Institute of Architects, the 1 Society of Engineers, the Town Planning Institute, an engineer representing municipal and county engineers, and the Government town planner. “These proposals may seem a very drastic course of action,” the report concludes, “but the Institute would remind the Government that it is only by sucli. a course that any degree of protection can be afforded to those people of New Zealand living in the earthquake danger zones. A force

Rossi-Forel 10 earthquake has twice rocked Wellington in the last 100 years, and should an earthquake of such force occur in Wellington today, the loss of life and damage would be fearful to contemplate. “The action now being taken in Wellington in removing parapets, and building in concrete bands, is of course a very considerable help in reducing the danger to the public for an earthquake of force Rossi-Forel 8, such as Wellington recently experienced, but will be of little value in preventing the collapse of such buildings in the case of a really bad earthquake. “By allowing towns and cities in the danger zones to remain as they arg apart from the reduction of parapets, etc., a very large sum will be invested each year in earthquake insurance. Such insurance will not prevent the collapse of buildings, but only provide the money for their rebuilding or patching after the catastrophe. The course advocated by this institute, that is a rebuilding scheme after the war, will reduce the necessity for such insurance, and in fact a large part of the interest cost of such rebuilding can be met by this saving. Towns and cities thus rebuilt would become safer, efficient, and beautiful centres.”