3 December 2007

Researchers from UQ’s Earth Systems Science Computational Centre (ESSCC) who were able to predict a series of three large Sumatran earthquakes that occurred in September, will present their ground-breaking research at the Fall Meeting of the American Geophysical Union (AGU), held from December 10 to 14.

In this, the Union’s 40th year, the meeting is expected to draw a crowd of over 15,000 of the leading geophysicists from around the world, to present and review the latest breakthroughs on issues affecting the Earth, the planets and their environments in space.

Research team leader, Dr Huilin Xing, said the AGU’s last-minute inclusion of the UQ research in an added special session entitled “The 2007 Sumatra Seismic Sequence” reflected the significance of the work.

The predictions were made using advanced computer simulation software developed as part of a research program under Dr Xing, with researchers utilising the ESSCC’s Altix supercomputer – one of the fastest in Australia – to model scenarios and determine the highest risk areas.

As a result of their simulations, Dr Xing and his colleagues identified the part of the subduction zone where the Eurasian and Indian/Australian tectonic plates meet between latitude S1° and S5.5° as having the highest earthquake risk – exactly the zone in which the series of quakes occurred.

Dr Xing said that in the wake of the 2004 Boxing Day tsunami, the Sumatra region was one of the first areas of application for the modelling software.

“Not too long after we developed the software the 2004 Boxing Day tsunami occurred and as a result, we began a project specially focused on the tsunami generation process induced by earthquakes and from there, we really began the research for the Sumatra area,” he said.

“The region had a lot of data and papers related to it as a very hot topic, and all that information was ideal for helping us conduct the simulations.

“We presented our results as early as last April in Hawaii, highlighting the high earthquake risk in this very specific area… and now already the event has happened with the three earthquakes occurring in exactly the place we had predicted – and this is why we’re very excited but in some ways quite shocked.

“This sort of event is very rare in earthquake history – to have three very large earthquakes occur so close together but also in a very narrow area.”

The three quakes, which occurred in the space of just two days, were measured on the Richter scale at magnitudes of 8.4 and 7.9 (September 12), and 7.0 (September 13) respectively. Residents living around the Indian Ocean were quick to register their shock at the magnitude of the tremors, which were felt as far away as Singapore and Malaysia.

Interestingly, the area was one of very few in the wider Sumatran region that had not experienced earthquake activity for some time. But the extended period of quiescence did not discourage Dr Xing and his colleagues from pinpointing it as high-risk zone.

“It was very strange that even in this region of high earthquake activity and in which the tsunami-inducing earthquake occurred, that this particular area seemed to be locked.

“But while on the one side this could have meant that perhaps this area was very safe because there was no slip, on the other side the lack of any slip meant a significant build-up of force and that the area had a large amount of energy to release.

“When we looked at the earthquake history around this area we found that about 170 years ago there were two very large earthquakes exactly in this area, so we began to think this area might have potential for a large, destructive earthquake in between the relatively long periods of quiet.”

Despite the accuracy of the UQ forecast, Dr Xing was quick to point out that the prediction of earthquakes is not an exact science and said the recent series of earthquakes have in many ways only added to the many questions surrounding the subject.

“For example, from research we know we can expect that if an earthquake is larger than magnitude 6.5 there may be a tsunami, and while this is not directly or linearly related to size, it is very important.

“But in this case the first earthquake was of magnitude 8.4, and there was almost no tsunami…and I think this means we really need to keep looking deeper to work out what kinds of earthquakes can generate tsunamis and how big the tsunami might be.

“If we continue this research, we can help to make the prediction of earthquakes and tsunamis a more accurate process, contributing some further understanding of the factors involved and with respect to this particular area, modelling where the next event might occur.”

And with the third anniversary of the Boxing Day tsunami fast approaching, Dr Xing said researchers were faced with a tragic and timely reminder of just how important any such advances could be.

In the meantime, his finite element crustal dynamics software is currently being applied in the supercomputer simulation of hot fractured rock geothermal reservoir systems in the field of alternative energy, and has demonstrated other significant potential applications in regards to modelling the deep geological disposal of nuclear waste and carbon dioxide.

Dr Xing said it was important to acknowledge the support he has received from the Australian Computational Earth Systems Simulator (ACcESS) – a major national research facility hosted by the ESSCC; as well as the Australian Research Council and industry collaborators, such as Geodynamics Ltd.

The ESSCC conducts research on the mechanics and physics of solid Earth processes on all scales using supercomputer simulation and by applying the methodologies of geophysical fluid and solid mechanics.

Media: For further information, please contact Lucy Manderson at UQ Communications (07 3365 2339 or l.manderson@uq.edu.au) or Dr Huilin Xing via email at h.xing@uq.edu.au.