As a result of an earthquake, thought to have been centred about 400 miles from Perth, Western Australia experienced yesterday probably its most severe earth tremor. The shock was felt in practically every part of the State and was recorded on seismographs as far away as Sydney. It is thought likely that the earthquake occurred in a seismic belt known to exist some distance off our west coast, but observations received from the Eastern States last night indicated a possibility that the centre was somewhere east of Geraldton. It will not be possible to fix the locality exactly until furhter information is received from other observatories. In the metropolitan area, buildings wee rocked, loose objects were rattled and suspended objects were left swaying for some time after the shock had passed. The shock was felt as a swaying motion rather than a tremor, and hundreds of people, feeling themselves swaying unaccountably, immediately jumped to the conclusion that they were fainting. After the occurrence numerous stories were told of people who felt themselves swaying and remarked "I don’t feel well" only to receive the reply "neither do I". On the other hand many people felt nothing unusual. In the taller city buildings the shock was magnified to such an extent that occupants of the upper floors left their offices in alarm and hurried downstairs into the street. In one or two cases windows were cracked by the shock. Seismograph Record The first intimation received by the Government Astronomer (Mr. H. S. Spigl) was a telephone message from an officer at Swan Barracks, who had noticed a distinct movement of the table at which he was sitting. So prompt was the notification that Mr. Spigi was able to reach the seismograph while the shocks were still being recorded.. The preliminary waves of the disturbance reached the Observatory at nine hours 37 minutes 4 seconds in the morning, and the long waves followed at 9.40 a.m. The maximum movement of the light spot was 12in, indicating a very severe shock. The instrument was still in violent commotion an hour after the first waves were received, although the actual shock only lasted probably two or three minutes. It was explained by Mr. Spigl that the movement of 12in was a very much magnified record of the actual earth movement, which would be only slight. The shock would be similarly magnified, he said, in a tall building, and a movement of half an inch on the ground could quite easily be three or four inches on the top floor. Location of Disturbance Referring to the probable centre of the disturbance, Mr. Spigl said that there was a definite seismic belt in the Indian Ocean extending from a position off North-West Cape to a position some distance west of Geraldton. The shocks were felt along the south coast and for distances 800 miles north and 500 miles east of Perth, but the most severe shocks occurred in the vicinity of Geraldton. The time taken between the reception of the preliminary waves and the recording of the long waves indicated that the earthquake occurred about 400 miles from Perth. This would appear to indicate that it was somewhere in the seismic belt referred to, but reports from Sydney and Adelaide((COPY UNREADABLE HERE) ---- there was a possibility ---east of Geraldton --- able to fix the location --- further observations -- from ManilaThe only comparable --- )recorded in Perth he continued, occurred in 1906, when an earthquake in the Indian Ocean was felt over an extensive area of Western Australia. In was difficult to compare the severity of the two earthquakes as the instrument in use then was much less sensitive than that being used today. It was fairly certain, however, that yesterday’s shock was at least as severe as that experienced in 1906. All the delicate instruments at the Observatory were affected, said Mr. Spigl, and the boom of a barograph in the Observatory porch was swung right off the cylinder. The main time clock, which sends out all the time signals, was stopped, and the transit instrument, which is mounted on stable granite pillars and protected from all surface movements, was affected. from The West Australian | | Many residents were alarmed and activities came to an abrupt, if momentary halt in Geraldton as the result of a severe earth tremor which shook the town at about 9.38 o’clock this morning. The morning was close and oppressive with a threat of further rain. People in business had comfortably established themselves at their various everyday tasks and another routine day had commenced. Suddenly attention was directed to a severe rumbling noise, which many at first mistook for the passage of some heavily laden vehicle past their premises. Curiosity quickly gave way in many instances to concern as windows commenced to rattle, followed by the distinct swaying of walls and buildings. Floors appeared to move disquieteningly as many rushed for the out of doors. In all streets of the town small crowds congregated to exchange their experiences and conjecture on the nature of the disturbance responsible for the shock. Others stood in mute astonishment waiting wonderingly to ascertain what the disturbance was all about. However, the shocks ceased as quickly as they had commenced and after a brief luff life was resumed and business proceeded as usual. No reports of serious damage are to hand, although the dislodgement of plaster from walls and ceilings and the cracking of window panes have been reported. The Geraldton Guardian and Express, Tuesday April 29, 1941 | |