Tsunami danger for Australia passed
29 March 2005
There have been concerns about the potential for a tsunami following a very large earthquake with a magnitude of 8.7 which occurred off the coast of northern Sumatra at 2:09am today (Australian Eastern Standard Time).
Dr Ray Canterford of the Bureau of Meteorology said a 25cm tsunami was measured by the Bureau's tide gauge at Cocos Island, compared to the Boxing Day tsunami which measured 35cm. He said emergency services organisations were advised by the Bureau's Perth office shortly after the event since this height can in some circumstances translate to problems for coastal activities including industrial operations.
On the Australian west coast, a 25 - 30cm wave was observed at Geraldton at approximately 6.00am Western Standard Time. Perth observed a wave of about 10 cm at 6:20 am (Western Standard Time). It is expected that there will be continuing irregularities in the tides and currents for at least the next 12 to 24 hours.
The earthquake's epicentre was located approximately 205 km west north-west of Sibolga, Sumatra, Indonesia, and 245 km southwest of Medan, Sumatra. This earthquake occurred off-shore at a depth of about 30 kilometres. This is south-east of the Boxing Day earthquake, and there were six after-shocks in the two hours following the earthquake.
"There are reports of deaths and damage as a result of the earthquake on Nias Island off Sumatra," said Dr Cummins. "Other regions in the Indian Ocean have recorded waves measuring up to 40cm, but there have been no reports thus far of any significant tsunami impacting on these regions."
This earthquake is the result of plate collision, caused by the Australian plate moving northwards beneath Sumatra at about 7cm per year.
For recent tsunami information, visit the Bureau of Meteorology website - www.bom.gov.au/marine/forecasts.shtml.
For a list of the most recent earthquakes or to report a felt event visit the Geoscience Australia website - www.ga.gov.au/earthquakes/.
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