Tsunami warning a first for me – April 3, 2007

The risk of earthquakes may be part of “life as usual” in California, but tsunami warnings are not commonplace in Australia.

So Monday morning’s urgent warnings that a tsunami could hit Australia were strange broadcasts to hear on the radio while driving to work or school. The instructions were to stay away from the water in any coastal area, and to be prepared for further evacuation instructions if they should become necessary.

My Canadian friends may be wondering what all the fuss was about, since news from the Pacific doesn’t often reach North America. Here is some background info (with thanks to The Age newspaper for some key details):

  • At 6.40am Queensland time, a large earthquake in the Solomon Islands triggered a tsunami. It swamped many of the Solomon Islands, causing tremendous damage and at least 20 deaths (beyond the mayhem of the quake, bad enough).
  • The Australian Bureau of Meteorology received the first bulletin from the Pacific Tsunami Warning Centre in Hawaii, when the quake measured 7.8 on the Richter scale. This level would not usually be enough to raise a tsunami concern beyond the northern coast of Queensland and the Willis and Barrier Reef islands.
  • But by 7.30am, the quake had been reassessed at 8.1! The tsunami alert was extended to cover Queensland’s east coast, and warnings were issued for the NSW coast, Lord Howe and Norfolk islands and Tasmania’s eastern coastline — that is effectively the entire eastern coast of Australia!

Fortunately, the tsunami’s impact on Australia was nowhere close to the expectation. The sea level rose 20-25 cm near the Torres Strait, Cairns and Townsville but there was no real impact to Willis Island (an early warning station) nor to Cooktown, Qld where it had been expected any big waves would first strike the mainland. Many Queenslanders on the front-lines, however, were not impressed by the tsunami warning centre’s communication with local authorities and residents — Some mayors and senior officials first heard about the tsunami warning when the Australian Broadcasting corp. called them for interviews!!

The seismological history of the Solomon Islands area indicates that there will be more earthquakes and aftershocks for several weeks — and I heard this morning that a large quake, often as large as the first, tends to follow. But keeping Monday’s quake in context, it was 40 times lower in terms of energy output than the 2004 Boxing Day quake and resulting tsunami. The ’04 version measured 9 on the Richter scale and killed more than 200,000 people, prompting the Australian government to commit $68.9 million to upgrades of the tsunami alert system and establishment of a public warning system.

In all, Aussies and temporarily-transplanted Canadians like us should get used to the idea of hearing tsunami warnings in the future!

Read more on the Solomon Islands quake and tsunami warnings in Australia: