Today, an 8.7 magnitude earthquake occurred off the eastern coast of Kamchatka in Russia, leading to tsunamis in various parts of Russia and Japan. In Hawaii’s Maui Island, a tsunami wave exceeding 1.5 meters was observed. What type of earthquake is this? And why has it caused such widespread impact?
Gao Mengtan, a distinguished expert at the Earth Physics Research Institute of China Seismological Administration, explained that the eastern part of the Kamchatka Peninsula is an important component of the Pacific Ring of Fire. Here, the Pacific Plate plunges westward and northwestward towards the lower crust of North America at a rate of 7.7 centimeters per year, accumulating a lot of energy and releasing it as earthquakes. This region has always been a place with strong seismic activity; in 1952, a 9.0 magnitude earthquake occurred here. Therefore, major earthquakes in this area are normal tectonic activities.
It was introduced that the 8.7 magnitude earthquake in Kamchatka is also the strongest earthquake globally since the 9.0 magnitude earthquake in Japan in 2011. According to the China Earthquake Network Center, the depth of the earthquake was 10 kilometers. With a large magnitude and shallow source, it is highly likely to trigger a transoceanic tsunami.
Gao Mengtan stated that the type of earthquake in this event is a shallow-focus reverse thrust earthquake. Such earthquakes occur close to the seabed. Additionally, reverse thrust earthquakes can cause deformation on the seabed. In fact, tsunamis are triggered by sudden seabed deformation. An 8.7 magnitude earthquake is more likely to trigger a tsunami, capable of crossing oceans.
Gao Mengtan mentioned that there would be no tsunami impact on our country due to this earthquake. In Japan’s southern region, the tsunami has already subsided below 10 centimeters, so there will not be any larger tsunami further away.
Is it common for earthquake magnitude revisions after strong quakes?
After the Kamchatka earthquake, China’s Earthquake Network first officially measured it at 7.9 magnitude, which was later revised to 8.7 magnitude. Seismic detection agencies from countries like the United States, Germany, and Russia have also revised the earthquake magnitude. Experts say that revising the magnitude of a strong earthquake is very common.
Sun Li, a researcher at the China Earthquake Network Center, said that during the earthquake reporting process, it is important to strive for as accurate and timely a release of basic information about the earthquake as possible, using only some of the information from the seismic waves. As more information is received from global stations over time, the measurement of the earthquake’s magnitude can become more precise and reflect the energy released by the earthquake more accurately. The difference between an 8.7 magnitude and a 7.9 magnitude can affect the analysis of seismic activity and disaster assessment, hence the revision of the magnitude was initiated.
A strong earthquake occurred off the eastern coast of Kamchatka