The Earth's Got The Shakes

Did you know that Gisborne experiences at least one earthquake per day?... of insufficient strength to be felt by a human being. So the records of the seismometer at the Massey Road sub-station tell us.

Installed by the D.S.I.R., of Wellington, several months ago, to form a triangle of units centreing on the proposed Motu River hydro dam site, to record earth movements in the area, the seismometer operates by exposing a needle of light onto a revolving roll of bromide paper. Each day the paper is changed and developed, and almost without exception, at least one tremor is apparent.

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A small quake, recorded by the machine, is evident by the erratic line running across the sheet. It is of interest to note that the quake builds up to a climax and diminishes over a period of several minutes.

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Brian adjusts a portion of the elaborate timing device. The radio at right is tuned to 2YA to receive time pips.

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Sub-station operator Brian Walters changes a roll of paper on the galvamometer (recording machine)