’QUAKES OF 1932

Gisborne Times, Volume LXXIII, Issue 11828, 9 January 1933, Page 4

’QUAKES OF 1932

HUNDREDS RECORDED

AIMS OF RESEARCH WORK.

Hundreds of earthquakes were recorded in Christchurch during 1932 at the Magnetic Observatory, the places ol origin of which were widely distributed over the entire wo-rld, states ‘The Press’ (Christchurch). As a result of these recordings and work done in co-operation with similar stations in scores of countries the work of seisinological research is making as steady advance as that in any other branch of science.

To the average citizen there is much that is terrifying in earth tremors of any violence, but to the seis mologist the course and type of the tremor are interesting and important Earthquake research work promotes public safety: aims to enlist the interest of engineers, architects, contractors insurance men and property owners in the obligation to protect the community against disasters dne to earthquakes and earthquake fires by showing that it is reasonably practicable and economical to build for security ; and promotes a better understanding of the fact- that - earthquakes are dangerous chiefly because adequate precautions are not taken against their effects, whereas it is possible to insure against damage by proper studies of their geographic dn tribution. historical sequence activities and effects on buildings. The first record of a shock is caused by the fastest waves, which cause oscillation of the instruments and in an interval of some minutes there is a similar recording which is due to the reflection of the waves at thc<®g§p

centre of origin and the centre of recording. Sometime; there i; a double reflection.

Later evidences of shocks are recorded as slower waves which help to determine the origin of a disturbance : and the final characteristic which is made np of long cr large waves which are generated only along - the earth's outer mantle. There is f no limit to the distance that surface or long waves can travel if the earth quake is sufficiently severe, and it is not- uncommon for them to be record- , * ed at tbc one observatory two or tnree times. As an instance, the Solomon Island upheaval in October, 1931. was recorded at the Christchurch observatorv more than once. Then the Duller earthquake wa £ readily identified in Spain by surface waves.

ASCERTAINING THE STRUCTURE OF: THE EARTH.

Seismology enaTJles deductions to be made as to the structure of t-he earth This is a very active line of research in modern seismology and already seismologists talk of subdivisions of the surface layer, which is of great importance in locating the exact een tre of a near earthquake- It is possible to ascertain at what depth a shock originated. Some are near the surface and others as much as 125 miles down in the earth.

New Zealand as a whole lies in an active seismic zone, while during the last 100 years shock centres have been well distributed. To quote a few. there wa s the tremendous earthquake in the fiord region in Southland in 1827. the earthquakes in Auckland in 1834 ami 1535. the fairsized shocks which alarmed Wellington in 1855. the Amuri earthquake in ISSS, the Cheviot earthquake in 1901, the Buller shock in 1929. and the Hawke’s Bay earthquake in 1930. There is an altogether different aspect of the science also. Already seismology ha s proved of use in locating valuable ores and oil in many parts of the world. The great, oil companies use seismology extensively for investigating the underground structure of likely areas. The method used is to cause small earthquakes by firing explosives underground and the results are recorded. The decision of an oil company to spend £40.000 in research in oil fields in New Zealand is another instance of how knowledge gained by research is being put to practical use.