Mokuyō Seamount

Mokuyo is one of the Shichiyo Seamounts, named for the seven days of the week. Mokuyo ("Thursday") is a basaltic andesite submarine volcano that rises 1,780 m from the sea floor to within less than 1,000 m of the surface. The summit crater is 3 x 2.3 km and about 450 m deep with a 180-m-high lava dome in its center. Major hydrothermal activity was observed in July 1990, and the volcano was reclassified as active by the Japan Meteorological Agency.