In general, Hawaiian volcanoes during their most-active tholeiite
shield stage can be characterized as having gentle slopes extending
from the sea floor up to a summit caldera. The submarine slopes
of Hawaiian volcanoes are steeper than the subaerial slopes but
even they rarely exceed 14º (Mark & Moore 1987).
In the alkalic stage the caldera is usually filled in and as noted
earlier the slopes become steeper. The greater proportion of explosive
activity provides a good deal of ash causing Hawaiian volcanoes
in their post-shield alkalic stage to resemble strato volcanoes
to some degree. The most prominent large-scale structures are
calderas and rift zones.
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