Unforeseeable timing of megatsunamis: Explanation of the uncertainties involved
In a dramatic turn of events on July 30, 2023, at 12:25am BST, a massive earthquake with a magnitude of 8.8 struck off the coast of the Kamchatka Peninsula, Russia. This earthquake, a megathrust quake, is the sixth-largest in recorded history.
The epicentre of the earthquake was located in a region that is sparsely populated, which may affect efforts to model the region. However, the magnitude, location, and depth of the earthquake were factors used in issuing tsunami warnings, with more than two million people across the Pacific ordered to evacuate.
Tsunami warning systems, consisting of multiple centres worldwide, use data from past quakes and complex computer models to decide whether to sound the alarm. Seismic waves travel around 100 times faster than tsunamis, allowing for early warnings. The first alerts for a tsunami can go out just five minutes after the ground stops shaking.
The July 30 earthquake is not an isolated event. Alison Raby, a professor in environmental fluid mechanics at the University of Plymouth, UK, states that each earthquake brings fresh understanding and fresh questions for seismologists and earthquake engineers. Megathrust earthquakes, such as the one in Kamchatka, occur in subduction zones where one tectonic plate is forced under the other. They are also responsible for the 2004 Indian Ocean earthquake and the 2011 Tōhoku earthquake in Japan, which produced towering tsunamis with waves more than 30m (100ft) high.
Despite improvements in predicting tsunamis, there is a delicate balance between triggering evacuations for potential tsunamis and avoiding false warnings. People may become cynical about evacuations due to potential losses and traffic accidents, which could pose a danger of too many false warnings. Alison Raby remains optimistic that improvements are being made but acknowledges that they are not in a perfect prediction situation.
Raby's research on tsunamis has been published in peer-reviewed journals such as the International Journal of Disaster Risk Reduction and Marine Geology. Her work aims to improve our understanding of how tsunamis form and how they can be predicted more accurately.
The tsunami warnings for most coastal areas after the July 2021 Kamchatka Peninsula earthquake were lifted because, although the earthquake was very large, the resulting tsunami waves beyond Kamchatka were smaller than initially feared, causing less damage than expected. This serves as a reminder of the complex nature of tsunamis and the ongoing efforts to improve our ability to predict and respond to them.
In conclusion, the July 30 earthquake off the Kamchatka Peninsula is a stark reminder of the power of nature and the importance of robust tsunami warning systems. While progress is being made, there is still much to learn about predicting and responding to megathrust earthquakes and the tsunamis they can generate.
