Curtin University has completed installation of 20 new ocean-bottom seismometers off Western Australia’s coast, significantly improving earthquake detection capabilities in a geologically active region that poses tsunami risks to coastal communities.

The seismometers sit on the seafloor at depths of 3,000-5,000 metres along the Australian-Indonesian plate boundary, where the Australian plate subducts beneath the Eurasian plate. This zone generates earthquakes regularly, including the magnitude 9.1 quake that triggered the devastating 2004 Indian Ocean tsunami.

Professor Phil Cummins, who leads Curtin’s earthquake research program, said the offshore instruments provide much better data than land-based monitoring. “Seismic waves travel through the ocean floor faster and with less distortion than through continental crust. We can detect earthquakes minutes sooner and more accurately determine their magnitude and location.”

Those minutes matter for tsunami warning. The 2004 tsunami reached northern Sumatra within 15-20 minutes of the earthquake. Faster, more accurate detection means people get more time to evacuate.

Australia’s tsunami warning system relies on a network of seismometers, ocean buoys, and tide gauges operated by Geoscience Australia and the Bureau of Meteorology. The system has improved substantially since 2004, but offshore seismic monitoring in the eastern Indian Ocean remained sparse until now.

The new instruments include pressure sensors that can detect tsunami waves directly by measuring minute pressure changes as waves pass overhead. Combined with seismic data, this helps distinguish between earthquakes that generate tsunamis and those that don’t.

Not all undersea earthquakes create tsunamis. The earthquake needs to displace significant volumes of water, which typically requires vertical seafloor movement. Shallow thrust earthquakes where one tectonic plate pushes under another tend to generate tsunamis, while deeper earthquakes or strike-slip events often don’t.

Determining an earthquake’s mechanism quickly enough to predict tsunami generation is technically challenging. The new offshore instruments provide better data about fault geometry and rupture characteristics, improving real-time assessments.

The seismometer network cost $18 million to design, build, and deploy. Funding came from the Natural Disaster Resilience Program and the Australian Research Council. Additional funding supports data analysis and maintenance over the instruments’ expected 5-7 year operating life.

Maintaining subsea instruments is expensive and logistically complex. The seismometers sit unattended on the seafloor recording data continuously. Every 12-18 months, a research vessel must retrieve them, download data, replace batteries, and redeploy them.

That means data is not available in real-time, limiting the instruments’ utility for tsunami warning. However, the data is invaluable for understanding regional seismicity patterns, earthquake frequency and magnitude distributions, and long-term changes in tectonic stress.

Curtin is developing next-generation instruments that transmit data acoustically to subsea nodes connected by fiber-optic cables to shore. That would enable real-time data access while maintaining the superior detection capabilities of seafloor instruments. But undersea cable installation costs millions per kilometre, limiting where this approach is practical.

The seismic network also serves research purposes beyond tsunami warning. Understanding earthquake processes in subduction zones helps scientists assess seismic hazards and develop better building codes and emergency response plans.

Western Australia is generally not considered highly seismic, but the offshore plate boundary produces regular earthquakes, occasionally exceeding magnitude 7. While these pose limited direct shaking risks to Australian cities, they create tsunami potential.

Geoscience Australia’s probabilistic tsunami hazard assessment, published in 2024, identified several WA coastal towns where tsunami risk exceeds acceptable thresholds. That assessment informed updated emergency planning and triggered discussions about coastal infrastructure resilience.

The offshore seismometer data will refine those hazard assessments. Better understanding of how often different magnitude earthquakes occur, and which ones generate tsunamis, leads to more accurate risk estimates.

One interesting finding from early data is that the plate boundary experiences many more small earthquakes than previously detected by land-based monitoring. Improved detection of small events helps scientists understand the stress state of the plate boundary and potentially identify areas accumulating stress that could rupture in larger earthquakes.

Some researchers believe that patterns of small earthquake activity can provide early warning of larger events, though this remains controversial. The idea is that changes in the frequency, location, or characteristics of small earthquakes might indicate increasing stress before a major rupture.

The offshore network is coordinated with similar Indonesian monitoring systems through bilateral research agreements. Indonesia has invested heavily in earthquake and tsunami monitoring since 2004, deploying hundreds of seismometers and ocean buoys.

Data sharing between Australian and Indonesian monitoring systems improves tsunami warning for both countries. A tsunami triggered off Indonesia could reach WA within 2-3 hours, while a tsunami triggered off WA could reach Indonesia even faster.

Regional cooperation on natural hazard monitoring is one area where scientific collaboration works well despite occasional diplomatic tensions. Both countries recognise the mutual benefits of shared early warning capabilities.

The seismometer project is part of broader efforts to improve Australia’s natural disaster monitoring and warning systems. Similar investments are being made in bushfire detection satellites, flood monitoring networks, and severe weather forecasting capabilities.

Whether these investments reduce disaster impacts depends partly on how communities respond to warnings. The best warning systems are useless if people don’t understand them or don’t take protective actions. That requires public education and regular emergency exercises, not just technical infrastructure.

The subsea seismometer network will operate through at least 2032, providing a decade of high-quality data about one of Australia’s most significant but under-monitored natural hazard zones.