The Japanese government says at least 100 hectares across two municipalities of Ishikawa Prefecture were flooded by tsunami following Monday's massive earthquake.

The land ministry conducted an analysis of Suzu City and Noto Town on the Noto Peninsula, along the Sea of Japan, using aerial imagery provided by a prefectural rescue helicopter.

Areas confirmed as flooded include 15 hectares of Iida Port in Suzu City; and 27 hectares in Nunoura and Kurikawashiri in Noto Town.

The extent of the damage to houses or the depth of the flooding remains unknown.

Tsunami hit wide areas following the quake. Ministry officials say the true extent of the flooding will likely be larger.