THURSDAY’S EARTHQUAKE.

Hokitika Guardian, 23 June 1920, Page 4

THURSDAY’S EARTHQUAKE.

Dr 0. E. Adams, Government Astronoifie'r informed a “New Zealaiid Times” representative that the seismometer at the Observatory, Kelburn, had recorded the tremors experienced on Thursday last. lie had developed the photographic negative which registered the shocks, but the negative had not dried last evening. It was apparent, .however, that the earthquake was quite local in its origin. A peculiar result of the earthquake,, according to the seismograph, is that it has left the earth’s surface with a tilt of one second of an arc towards the westward. Dr Adams explained that the earth may slowly sudeide into its noma] level. As there are 324,000 seconds in the 'rs from the horizontal to a vertical point, the one second tilt is not likely to occasion inconvenience to local residents. No one, of course, has any desire for the phenomenon to make a habit of "his tiling process, as, if repeated too often it would put buildings out of plumb. The fact that two distinct- shocks are experienced generally is ascribed to two distinct waves moving out from the point of disturbance. What arg known as the waves of compression and distortion through the interior of the earth’' and they arrive at any locality more than seven hundred miles distant from the origin before the larger surface waves. The former arc felt as a series of preliminary tremors before the main earthquake shoeK, which has travelled around the stir, face. Scientists state there are between' 30,000 amf 40,000 earth-quakes every year, the greater majority being local in charqpter; a large lumber are known to have occurred only by records of the seismometer.