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The earthquake in Russia's Kamchatka peninsula on July 30, 2025, may have been one of the most severe on record, with a magnitude of 8.8. But innovations in science and technology gave governments vital time to warn and evacuate their people from the resulting tsunami.

Millions of to higher ground before the tsunami hit.

The 2004 Boxing Day 9.3 magnitude earthquake and tsunami in Sumatra, which caused approximately , some as far away as Somalia on the other side of the Indian Ocean, shows how important these warnings are.

Early warning systems were not in place for the Indian Ocean in time for the 2004 disaster. But there is now a system in place, with .

The 2004 tsunami was particularly tragic because tsunami waves travel at a steady speed in the open ocean, about . This means they can take several hours to reach shore across an ocean, with plenty of time for warning.

An for the Pacific Ocean, based in Hawaii, was created in 1948 following a deadly tsunami two years before. On April 1, 1946, the magnitude 8.6 Aleutian Islands earthquake in the northern Pacific Ocean generated a tsunami that devastated parts of Hawaii hours later, leading to 146 fatalities.

The death toll was exacerbated by the . This happens in around 50% of tsunamis, and exposes the seashore in a similar way to when the tide goes out, but exposing a larger area than normal. People sometimes investigate out of curiosity, bringing them closer to the danger.

The accuracy and response times of early tsunami warnings have since 1948.

How tsunamis happen

To understand the work involved in protecting coastal communities, first you need to understand how tsunamis are generated.

Tsunamis are caused by after an earthquake, landslide or volcanic eruption. This provides an energy source to set off a wave in the deep sea, not just near the surface like in the ocean waves we see whipped up by the wind and storms. Most are small. The Japanese word tsunami translates somewhat innocuously as "harbor wave."

Detailed global , pioneered by US geologist Marie Tharpe between 1957 and 1978, helped establish the modern theory of plate tectonics. It also improved the for how the tsunami will travel in the ocean.

Wave height increases as it approaches the shore, and the topography of the sea floor can result in a complicated pattern of wave interference and concentration of the energy in . The establishment of sea-floor observatories led to better data for the pressure at the sea floor (related to wave height) and satellite networks now directly monitor wave height globally using .

One of the factors that has helped scientists predict the range of a tsunami includes the setting up of the worldwide standard station network of seismometers in 1963, which allowed better estimations of earthquake location and magnitude.

These were superseded by the digital broadband global network of seismometers in 1978, which allowed more detail on the source to be calculated quickly. This includes a better estimate of earthquake size, the source rupture area and orientation in three dimensions.

It also tells scientists about the slip, which controls the on the sea floor. This data is used to forecast the time of landing, the amplitude of the wave on the shoreline, and its height in areas where the wave travels further inland.

The Pacific Ocean warning system now has 46 countries contributing data. It also uses for estimating tsunami height. The models developed as scientists learned more about earthquake sources, mapped features on the sea floor and tested model forecasts against outcomes.

Today's technology

The early warning systems we have today are due to a decades-long commitment to global research collaboration and . Scientists have also improved their . Recently they started using which could improve the timeliness and accuracy.

Pioneered by the US Geological Survey, rapid data sharing is now used earthquake parameters and make them available to the public soon after the rupture stops. This can be within minutes for an initial estimate, then updated over the next few hours as more data comes in.

However, the forecast wave height is inherently , variable from place to place, and may turn out to be more or less than expected. Similarly, large earthquakes are rare, making it hard to estimate how likely they are on average, and therefore to design appropriate mitigation measures.

The 2011 Tohoku earthquake and tsunami in Japan that had been put in place based on such hazard estimates. There were over 19,000 fatalities. As a consequence, their height has been increased to 12-15 meters in some areas.

Early warning systems also rely on rapid communication to the public, including mass alerts communicated by mobile phone, coordination by the relevant authorities across borders, clear advice, and advance evacuation plans and occasional alarm tests or drills. Although tsunami waves as they approach the shore, it is impossible to outrun one, so it is better to act quickly and calmly.

The effectiveness of warnings also means accepting a degree of inconvenience in false alarms where the tsunami height is less than that forecast, because this is inevitable with the uncertainties involved. For good reason, authorities issuing alerts will err on the side of caution.

To give an example, nuclear power plants on Japan's eastern seaboard were shut down on July 30.

So far it looks like the Pacific early warning system—combined with effective levels of preparedness and action by service providers and decision makers—has worked well in reducing the number of casualties that might have happened without it.

There will always be a level of uncertainty we will have to live with. On balance, it is a small price to pay for avoiding a catastrophe.

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