Sanriku (三陸) is a region of Japan. It is on the northeastern side of the island of Honshu. Sanriku combines the area of Aomori, Iwate and parts of Miyagi Prefecture. It was sometimes called Rikushū (陸州).

Map of Japanese provinces with the Sanriku region highlighted

Sanriku has an irregular coastline with 36 small bays. Each bay focuses impact power of ocean waves.[1] This was shown by the damage caused by the 2011 Tōhoku earthquake and tsunami.


In 1869, the provinces of Mutsu and Dewa were divided.

Mutsu was split into new five provinces: Rikuōku,[2] Rikuchū,[3] Rikuzen,[4] Iwashiro[5] and Iwaki.[6] The first three of these collectively known as the "Three Riku", or Sanriku.[7]

The new provinces were abolished in July 1871; however, the regional name is still in use as the Sanriku Coast from Aomori to the Oshika Peninsula in Miyagi.[8]


  1. Satake, Kenji. (2005). Tsunamis: Case Studies and Recent Developments, p. 99.
  2. Nussbaum, Louis-Frédéric. (2005). "Rikuōku" in Japan Encyclopedia, p. 790.
  3. Nussbaum, "Rikuchū" at p. 790.
  4. Nussbaum, "Rikuzen" at p. 790.
  5. Nussbaum, "Iwashiro" at p. 410.
  6. Nussbaum, "Iwaki" at p. 408.
  7. Nippon-Kichi, "Saw-tooth Sanriku Coastline"; retrieved 2012-1-12.
  8. Japan-i, Sanriku Coastline/Kamaishi Daikannon; retrieved 2012-1-12.