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Almost two weeks after the earthquake and ensuing tsunami that devastated huge areas of Asia, the Earth is still ringing like a bell, according to ANU scientists. Dr Herb McQueen, from the Research School of Earth Sciences, operates a gravity meter at Mt Stromlo Observatory and is still recording vibrations generated by the Boxing Day earthquake. "The main signal we now see is a steady oscillation of a few parts in 10 billion of normal gravity, which corresponds to about a millimetre of vertical motion of the Earth," Dr McQueen said. "The early signals were much stronger. The Earth is regularly deformed by the daily passage of the Sun and Moon, raising a tide in the Earth of about 20 centimetres, and the vibrations we saw on Boxing Day shortly after the earthquake off the Indonesian coast were of a similar magnitude on our instruments." "This is a relatively rare seismic event, which could still be making the Earth reverberate for another couple of weeks." The Superconducting Gravimeter is Australia's most sensitive gravity measuring instrument and is located at Mt Stromlo Observatory. It relies on the exotic superconducting properties of metals at extremely low temperatures to detect faint changes in gravity caused by tides and major earthquakes. These signals are used to map the structure of the interior of the Earth.
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More Than 2,500 Aftershocks In Wake Of Asia Tsunamis
Vienna, Austria (AFP) Jan 06, 2005More than 2,500 aftershocks have been recorded in the wake of the 8.9 magnitude earthquake which triggered devastating tidal waves in south Asia 11 days ago, the body set up to monitor nuclear tests said Thursday. |
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