On November 16th, a big 8.8 magnitude earthquake shook the Kamchatka Peninsula in Russia. It was an impressive seismic act as the ever-northwestward-moving Pacific plate got crammed under the North American plate at the Canada-Alaska border. This amazing geologic process is called subduction. The quake, as it is known, was a megathrust earthquake and one of the largest ever recorded. It has set off tsunami warnings and caused evacuations across the Pacific, affecting areas as far away as Chile, Hawaii, and Ecuador.
The Kamchatka earthquake is remarkable for what that size quake has wrought on the numerous countries encircling the Pacific Ocean. It was responsible for maximum wave heights of five meters in Kamchatka itself, with waves reaching an estimated 1.7 meters in Hawaii. Miraculously, though the earthquake had the makings of a truly devastating quake, not too much structural damage was done and there were no reported fatalities. If confirmed, this would be the biggest quake since the 2011 magnitude-9.1 quake followed by tsunami that struck off Japan’s northern coast.
Understanding Megathrust Earthquakes
Megathrust earthquakes, like the Kamchatka quake, happen when tectonic plates slip and slide under and over one another. These violent ruptures can in turn cause extremely large tsunamis. Dr. Stephen Hicks highlighted the scale of these phenomena, stating they “cause some of the world’s largest ruptures and trans-ocean tsunamis.”
The geological setting of Kamchatka has made the region particularly vulnerable to such seismic events. Here, the Pacific plate very gradually grinds alongside the North American plate, drifting a few centimeters a year. Friction slowly causes these plates to become latched. Over time, that pressure continues to accumulate and is eventually released in a much more noticeable form—an earthquake.
When megathrust earthquakes do strike, they can send out tsunami waves with enough height and energy to cover long distances across entire oceans. “They can be very small at sea,” Dr. Lisa McNeill shared, discussing what waves might look like. They can rapidly increase in height as they approach the deeper waters of the continental shelf. She noted that “a tsunami can have varied heights on one coastline,” leading to potentially surprising wave heights.
Tsunami Preparedness and Evacuations
The earthquake prompted immediate tsunami warnings across multiple countries, demonstrating the effectiveness of preparedness measures established in the Pacific since the 1960s. These seemingly simple systems save countless lives by giving communities early and actionable warnings that let them evacuate before it’s too late. One expert mentioned, “This has been established in the Pacific since the 1960s, and people therefore receive warnings about the tsunami and can evacuate.”
For people who live closest to the epicenter, they experience a set of challenges. When an earthquake hits, they don’t have much time to respond. The quake itself is their first and often their best warning of potential tsunami danger. One expert stated, “It is harder for those living close to the earthquake as they have less time, but the earthquake is their warning of a tsunami and [the] prompt to move to higher ground.”
As with any tsunami, the distance from the earthquake to the likely impacted areas makes all the difference in the tsunami’s dynamic. Meghan Miller pointed out that for the tsunami generated by the 2011 Japan earthquake, “the distances [to land] were much closer,” making the impact more immediate compared to the Kamchatka event.
