Which earthquake was the first to be measured at magnitude 9 or higher by modern instruments?

The 4 November 1952 Kamchatka earthquake in Russia was one of the earliest great earthquakes measured with modern seismographs at magnitude 9.0. It generated a Pacific tsunami and caused damage along distant coastlines. Because global seismic networks were less developed than today, it is important as an early benchmark in instrumental seismology. The event showed that very large subduction-zone earthquakes could occur in remote parts of the world and still affect entire ocean basins. It helped shape later tsunami warning and earthquake research.