Scientific modelling reworked in the aftermath of Japan shows that Australia is at greater risk of tsunamis than previously assumed, according to several international experts on tsunamis and earthquakes. The Pacific Ring of Fire, an area renowned for earthquakes and volcanoes, is the biggest concern for tsunamis along the east coast of Oz.
The world’s top seismologists are currently in Melbourne for the International Union of Geodesy and Geophysics (IUGG) conference, where they are exploring the issues of earthquakes, early warning systems and tsunamis after the Japan quake.
The Japan earthquake in March also proved to be deeper and more damaging than any prior scientific modelling predicted, resulting in wide ramifications for the study of seismology.
Many scientific modelling and predictions — including examining how an earthquake, volcano or underwater landslide in the South Pacific could cause a tsunami in Australia — are now viewed as vast underestimates in light of the Japan quake and tsunami.
“The events of the last year show us the earth is still full of surprises,” said Professor Thomas Jordan, director of the Southern California Earthquake Center and Professor of Earth Sciences at the University of Southern California.
Despite years of research, scientists are still unable to pinpoint exactly when and where an earthquake will occur. “It’s a very vexing problem, one of the great unsolved problems in our science,” said Jordan. Instead, the best scientists can do is make predictions of where the earthquake is likely to occur and how big it is likely to be, based on historical data.
However, Australia and the South Pacific are particularly limiting in the historical records available, with only about 200 years of written records examining earthquakes in the region even though much of it lies in the notorious Pacific Ring of Fire region.
Not that those predictions are always accurate anyway. The city of Wellington on the north island of New Zealand was seen as a more likely spot for a large earthquake in an urban centre in NZ than Christchurch, which was only rated as low-risk.
Yet it was Christchurch that was destroyed in February by the aftershocks from a quake last December and it will suffer further aftershocks from that quake for years, explained Professor James Goff, co-Director of the Australian Tsunami Research Centre.
Although accurate predictions of when and where earthquakes will occur is difficult, there are other advances that can and should be made. Jordan spoke of the need for operational earthquake forecasting, meaning short-term modelling of seismic activity and predicting when aftershocks will occur post the initial quake.
Early warning systems have proved to be highly affective for tsunamis, as the waves take a while to form and there is time for public warning systems to be deployed. It’s more difficult with earthquakes due to the small amount of time. Jordan says with the right equipment, nearby regions could get around a minute of warning time before a significant quake hit, which although only a small amount of time is enough to stop bullet trains (which Japan has done in the past), get out of a lift in a tall building and stop a surgeon during surgery.
Another issue with warnings is how quickly the public flout them or don’t take them seriously, says Goff. He spoke of how frustrating it was to learn that thousands of people went to Bondi Beach when tsunami warnings were issued last year in the hope of ‘watching’ the tsunami. “The warning system is not the problem, the people are the problem,” said Goff.
Earthquakes are not the only tsunami trigger in the South Pacific. Other factors which don’t get as much attention but could be even more damaging include volcanoes — since most South Pacific islands are either active or dormant volcanoes, which are slowly falling away — underwater landslides and sediment slumping.
Although there are only 200 years of written records, examinations of the Futuna island in the South Pacific found a volcano and resulting tsunami that destroyed an entire community on the island just 500 odd years ago. Goff says this is just one example of many that scientists are beginning to discover, which are helping to plan for the likelihood and regularity of future disasters in the region.