Which earthquake generated the strongest ground shaking ever measured by modern instruments?

The 11 March 2011 Tōhoku earthquake struck off the northeast coast of Honshu, Japan, with a magnitude of 9.0. It was one of the most powerful earthquakes ever recorded and caused intense shaking across a wide area. The quake generated a massive tsunami that devastated coastal communities and contributed to the Fukushima nuclear disaster. The event caused nearly 20,000 deaths and widespread damage. It changed tsunami preparedness and seismic engineering standards around the world.