Dr Bianca Cavazzin discusses the science behind tsunamis as alerts are issued after major earthquake off Russia.

This week’s magnitude 8.8 earthquake off Russia’s Kamchatka Peninsula ranks among the most powerful ever recorded.

It occurred in one of Earth’s most seismically active regions, where similar events have struck in the past, including a magnitude 9.3 in 1737, 9.0 in 1841, 8.5 in 1923, and 9.0 in 1952.

This was a classic megathrust earthquake: a powerful rupture along a subduction zone where the Pacific tectonic plate is forced beneath the Kamchatka Peninsula. These collisions can be extremely violent.

As the plates lock together, they accumulate strain over centuries, in this case at a rate of ~80 mm/year. When the fault finally gives way, energy is released suddenly, with the fault slipping tens of metres in just a few minutes. Today’s rupture occurred at a relatively shallow depth (~19 km), which increased surface shaking and triggered tsunami waves up to 5 metres along the Russian coast, with tsunami warnings extending as far as Hawaii, Ecuador and Chile.

It’s important to understand that large earthquakes do not come from a single point. Instead, the fault rupture extends over hundreds of kilometres. This vast rupture area is what contributes to the earthquake’s high magnitude and potential to generate ocean-wide tsunamis, as enormous volumes of water are displaced when the rupture reaches or penetrates the seafloor.

This event follows earlier activity in the same region: a magnitude 7.4 quake on 20 July 2025, and a magnitude 7.1 in August 2024. In hindsight, these are now likely to be seen as foreshocks, early signs of the larger rupture to come. Scientific analysis in the coming months will help clarify the sequence and mechanics of this cluster of events. Megathrust earthquakes send long-period seismic waves around the globe. These waves can travel for days, causing the Earth itself to resonate, a bit like a giant gong struck with force.

A note on terminology: when tsunami reports refer to ‘wave height’, they typically mean the maximum elevation above sea level, not the vertical face of the wave!

I’m often asked whether climate change causes earthquakes. The short answer is no, earthquakes of this magnitude are driven by deep tectonic processes, not by atmospheric or surface-level factors.

While some emerging research links glacial melt to small “microquakes” in alpine regions, these are not connected to major subduction zone events like this, especially not in non-glaciated regions like Kamchatka.

The relationship between climate change and tsunamis is more complex. While today’s tsunami was caused by tectonic movement, rising sea levels driven by climate change can amplify the impacts of tsunamis, especially in low-lying coastal areas. Higher sea levels mean tsunamis can travel further inland, reach higher run-up elevations, and cause more widespread damage to communities, infrastructure, and ecosystems.

Dr Bianca Cavazzin is Senior Lecturer in Physical Geography at Canterbury Christ Church University.