Short answers, pulled from the story.
The 2011 Tohoku earthquake measured magnitude 9.1 on the moment magnitude scale, as confirmed by the USGS in a final upgrade issued on the 11th of July 2016. It was the most powerful earthquake ever recorded in Japan and the fourth most powerful recorded anywhere in the world since modern seismography began in 1900.
Tsunami waves reached estimated heights of up to 40.5 m in Miyako, Iwate Prefecture. At the Aneyoshi fishery port on the Omoe peninsula in Miyako, the measured run-up height was 38.9 m, cited as a record in Japan, exceeding the 38.2 m from the 1896 Sanriku earthquake.
Official figures released in 2021 confirmed thousands of deaths, with Miyagi Prefecture recording 10,567, Iwate 5,145, and Fukushima 3,920. Drowning accounted for 90.64% of deaths, and people aged over 60 made up 65.8% of all fatalities.
Tsunami waves overtopped Fukushima Daiichi's sea walls and destroyed the diesel backup power systems. Without electricity, cooling systems halted, heat built in the reactors, and hydrogen gas accumulated and exploded in the refueling hall, leading to meltdowns in three of the plant's reactors.
Estimated economic damage exceeded $300 billion, making it the costliest natural disaster in history at the time. Early estimates placed insured losses from the earthquake alone at US$14.5 to $34.6 billion, and a 2020 study found the disaster caused a 0.47 percentage point decline in Japan's real GDP growth in the following year.
The tsunami propagated across the entire Pacific Ocean, reaching coastlines from Alaska to Chile. Chile's coast, approximately 17,000 km from Japan, was struck by waves 2 m high. The tsunami also broke icebergs from the Sulzberger Ice Shelf in Antarctica, 13,000 km away, releasing a total of 125 km2 of ice.