Tsunami event summary - Sunday, 28 February 2010

Details of earthquake:

Magnitude 8.8, centred off the central coast of Chile, South America at 5:34pm EDT on Saturday 27 February 2010.

Australia's warning response:

Saturday, 27 February 2010

  • 5:51pm EDT: Geoscience Australia releases initial earthquake magnitude assessment of 8.5.
  • 6:21pm EDT: No Threat Bulletin for Australia issued by Joint Australian Tsunami Warning Centre.
  • 7:45pm EDT: Tsunami watch issued, based on revised earthquake magnitude assessment of 8.8.
  • 8:48pm EDT: Tsunami Marine Threat Warning issued for Queensland (Point Danger to Double Island Point), New South Wales (Broken Bay to Point Danger), Lord Howe and Norfolk Islands.

Sunday, 28 February 2010

  • 4:00am EDT: Tsunami Marine Threat Warning expanded to cover Australia's East Coast from southern Tasmania (Low Rocky Point to Flinders Island), Victoria (Lakes Entrance to Gabo Island), all of the New South Wales coast, Queensland (Point Danger to St Laurence), as well as Lord Howe and Norfolk Islands.

Impacts on Australia

The tsunami was estimated to take approximately 15 to 18 hours to travel across the Pacific Ocean, and first began being observed on tide gauges at Australian locations on Sunday 28 February 2010 at:

  • Spring Bay, Tasmania - tsunami effects observed from 7:55am EDT, highest wave: 19 cm.
  • Southport, Tasmania - tsunami effects observed from 8:45am EDT, highest wave: 28 cm.
  • Norfolk Island - tsunami effects observed from 8:54am EDT, highest wave: 50 cm.
  • Portland, Vic - tsunami effects observed from 10:22am EDT, highest wave: 11 cm.
  • Eden, NSW - tsunami effects observed from 11:19am EDT, highest wave: 21 cm.
  • Port Kembla, NSW - tsunami effects observed from 11:20am EDT, highest wave: 29 cm (see image below).
  • Gold Coast, QLD - tsunami effects observed from 12:38pm EDT, highest wave: 42 cm.
  • Esperance, WA - tsunami effects observed from 1:45pm EDT, highest wave: 15 cm.

Sea level fluctuations outside normal conditions were recorded at many locations around Australia for more than 12 hours after the initial arrival of the tsunami.

Graph of sea level fluctuations at Port Kembla, NSW from a tsunami on 28 February 2010.

Figure 1: Changes in sea level at Port Kembla, New South Wales. The tsunami effects can be seen by the wider than normal fluctuations in sea level depicted by the blue line. The main effects of the tsunami were reported from the waves that travelled around the north of New Zealand, rather than from the waves that travelled around the south of New Zealand.