South-west ocean landscape provides natural tsunami protection

New research from The University of Western Australia has found the subsurface ocean features in the eastern Indian Ocean provide natural protection from the impact of tsunami waves in south-west Australia. 

These natural topographic features play a critical role in shielding towns between Geraldton and Busselton where more than 90 per cent of the population is located. 

The WA coastline experiences tsunamis through underwater earthquakes that originate from offshore Indonesiafrom the Sunda Trench, an oceanic trench in the Indian Ocean.

Professor Chari Pattiaratchi from UWA’s Oceans Institute carried out a range of numerical simulations of earthquakes to understand the transmission of tsunami waves to the region.

“It’s critical to understand how tsunamis travel in order to implement effective tsunami warning and mitigation.”

Professor Chari Pattiaratchi

The study, published today in the Journal of Marine Science and Engineering, examined the role of the surface and subsurface ocean topography that influenced the distribution of tsunami wave heights, propagating speed and direction.

Professor Pattiaratchi said the ocean features, seamounts and plateaus, including the Cuvier and Exmouth plateaus, acted as a natural shield by deflecting the tsunami waves.

“These ocean features influence the energy distribution of a tsunami following an earthquake event,” Professor Pattiaratchi said.

“If one of these features is struck, the tsunami will dissipate and scatter energy and reduce its impact on the south-west.”

“However, locations to the north of Shark Bay will experience higher waves.”

Professor Pattiaratchi said the offshore features each played a unique role in scattering and refracting the tsunami waves.

“For instance, the Exmouth plateau acts as a focusing feature to increase wave heights between North West Capeand Barrow Island while the Cuvier plateau deflects the wave energy towards the coast at Shark Bay,” Professor Pattiaratchi said.

“It’s critical to understand how tsunamis travel in order to implement effective tsunami warning and mitigation.”