Subaqueous volcano

[4] Some understanding of subaqueous volcanoes can be inferred from knowledge of volcanic processes based on ancient successions.

Unfortunately, paleo-depth constraints[clarification needed] for sedimentary strata are poor and subject to conflicting interpretations.

In determining the characteristics of pyroclastic flows in subaerial versus subaqueous deposits, it is commonly believed that water fluidized volcaniclastic flows become normally graded in terms of all components except for large, buoyant pumice blocks which settle to form large pumice layers.

Characteristics can be sorted[clarification needed] to infer subaqueous eruption or emplacement of silicic pyroclastic deposits.

Larger pumice blocks rise for a more extended period of time (minutes to hours) in comparison to smaller pumice fragments because of gases trapped within vesicles and the very fine ash fragments may become entrained into the rising plume of gas and heated water because of the low density and weight.

Seafloor exploration has discovered that more volcanic eruptions occur at the bottom of the sea than on land.

Studies of subaqueous volcanoes in Japan have concluded that clear evidence for eruption and/or emplacement of pyroclastic flows continues to require examination of these deposits, although inferential evidence such as grain morphology, sorting and grading can be used to identify and document ancient subaqueous volcanic deposits.