One thing that I've noticed is that there has been other quakes that precede and follow both the 1855 Ansei Edo quake and the 1894 Meiji Tokyo quake.
Is this significant? Well, I have no idea, to be honest, but I thought that it was worthy of noting, especially as northeast Japan had a massive one on 11th March.
One of the quakes, 15th June 1896 Meiji-Sanriku earthquake, was in a similar region, along the Japan Trench, to that of the March 2011 quake.
It must also be mentioned that the Japan Trench has regularly produced some huge quakes which can occur in locations extending from offshore Aomori Prefecture to offshore Ibaraki Prefecture,
Three of the top six quakes ever recorded worldwide, including the 2011 Tōhoku quake, appear to be clustered in a 6.2-year span between 2004 and 2011; however, experts construe this as a statistical anomaly or random chance.
Anyway, here's the quakes:
December 23, 1854 Ansei-Tōkai earthquake 8.4M
December 24, 1854 Ansei-Nankai earthquake 8.4M
November 11, 1855 Ansei Edo earthquake
April 9 1858, Hietsu Earthquake 7.0-7.1M
April 7, 1889 Kumamoto earthquake 6.3M
October 28, 1891 Mino-Owari Earthquake 8.0M
June 20, 1894 Meiji Tokyo Earthquake
June 15, 1896 1896 Meiji-Sanriku earthquake 8.5M