DESTRUCTIVE QUAKES

Dominion, Volume 35, Issue 289, 4 September 1942, Page 4

DESTRUCTIVE QUAKES

Wellington Ranks High In Dominion

REPORT BY N.Z. INSTITUTE OF ARCHITECTS

Following study of the effects of the recent two big earthquakes in the Wellington province by a sub-committee of the executive of the New Zealand Institute of Architects, a report has been issued emphasizing the need for a farreaching programme of rebuilding which would form part of post-war national rehabilitation schemes in areas subject to earthquake. “After the Napier earthquake,” the report states, “some local authorities brought in regulations designed to render any future building reasonably safe, but nothing was done about the vast aggregation of existing unsafe buildings. The retention of these is a constant menace to life and should not be allowed to remain any longer than is absolutely necessary.” It is mentioned that the two recent earthquakes were of force 8 intensity on the Rossi-Forel scale. “If one of them had been of force 10 (of which Wellington has had two during the past century) and had occurred on a busy shopping night, the death roll in the capital would have run to thousands and the property losses would have amounted to millions of pounds.” Quakes of a Century.

Leading up to a series of recommendations, the report gives abstracts from several bulletins issued by the Department of Scientific and Industrial Research concerning surveys of earthquakes (ranging from 6 to 10 on the Rossi-Forel scale) from 1834 to 1935, by the staff of the Dominion Observatory. No. 6 is big enough to cause alarm; No. 8 is destructive; No. 10 is disastrous. An analysis of the table given in the report shows that Wellington city, in the period reviewed, had 21 shocks of intensity 6, five of 7, 11 of 8, one of 9, and two of 10. Wanganui, in the same period, had 28 of intensity 6, four of 7, seven of 8, two of 9, and one of 10. Gisborne had 18 of 6, two of 7, five of 8 and one of 9. New Plymouth experienced 17 of 6, three of 7, five of 8, and one of 9. Napier had 27 of 6, six of 7, three of 8, and one each of 9 and 10. Masterton. had 14 of 6, four of 7. five of 8, none of 9, and one of 10 Palmerston North experienced la of 6, seven of 7, three of 8, and one of 9. Thus Wellington had a total of 14 destructive shocks (intensities 8,9, and 10), Wanganui had 10, Gisborne J, New Plymouth 6, Masterton 6, Napier 5 and Palmerston North 4. Sound Building Methods.

“A comparison with statistics from other highly seismic countries,” the report continues, “reveals that a large proportion of New Zealand’s destructive earthquakes are only of such an intensity that excessive damage may confidently ‘be avoided by careful attention to sound methods of buildin» construction throughout the whole country. Very special attention should be paid to construction in Wellington city. The rebuilding scheme should, be based on the soundest engineering, town-planning and architectural pnncl pl os. “Surveys made of the whole of NewZealand show that Gook (Strait is the centre of the highest seismicity and that the epicentres of major shocks (R.-F. 9 and 10), tend to congregate toward the eastern and southern parts of the' region. The earthquake frequency for Wellington city is given .as an average of 7 to 8 shocks of all intensities a year.” After a discussion of the sub-com-mittee’s report the executive set up a committee of five (including members who have specialized in town-planning and engineering) to make a further investigation and formulate a practicable policy suitable.for adoption by the Government.