All volcanic seamounts follow a particular pattern of growth , activity , subsidence and eventual extinction . The first stage of a seamount 's evolution is its early activity , building its flanks and core up from the sea floor . This is followed by a period of intense volcanism , during which the new volcano erupts almost all ( e.g. 98 % ) of its total magmatic volume . The seamount may even grow above sea level to become an oceanic island ( for example , the 2009 eruption of Hunga Tonga ) . After a period of explosive activity near the ocean surface , the eruptions slowly die away . With eruptions becoming infrequent and the seamount losing its ability to maintain itself , the volcano starts to erode . After finally becoming extinct ( possibly after a brief rejuvenated period ) , they are ground back down by the waves . Seamounts are built in a far more dynamic oceanic setting than their land counterparts , resulting in horizontal subsidence as the seamount moves with the tectonic plate towards a subduction zone . Here it is subducted under the plate margin and ultimately destroyed , but it may leave evidence of its passage by carving an indentation into the opposing wall of the subduction trench . The majority of seamounts have already completed their eruptive cycle , so access to early flows by researchers is limited by late volcanic activity
2009 eruption
2009 Tonga undersea volcanic eruption
Seamount