Dense-rock equivalent is a
volcanologic calculation used to estimate
volcanic eruption volume. One of the widely accepted measures of the size of a historic or prehistoric eruption is the volume of
magma ejected as
pumice and
volcanic ash, known as
tephra during an explosive phase of the eruption, or the volume of
lava extruded during an effusive phase of a volcanic eruption. Eruption volumes are commonly expressed in cubic kilometers (km
3).