Writing for Bloomberg Business, Gearoid Reidy reports that "an earthquake with a magnitude of 7.8 struck deep underground about 1,000 kilometers (621 miles) off Japan..." His story notes that "the agency [i.e. the Japan Meteorological Agency] reported an earlier preliminary magnitude reading of 8.5."
The Japan Meteorological Agency (JMA) has consistently reported a magnitude reading of 8.5 from the beginning and has not been stirred to lower the figure. It's the US Geological Survey that is reporting the lower magnitude reading of 7.8 and not the JMA.
The Bloomberg Newsroom contacted me via email to inform me that it got my message about the error and that the reporter updated the story.