Magnitude, whilst normally comparable to VEI (Crosweller et al. 2012), provides a more precisely defined quantitative measure of eruption size as a function of erupted mass, using Equation 1 (Pyle 2000): M = lo g 10 erupted mass kg - 7 (1).
M thus provides a continuous measure of eruption magnitude based on estimates of erupted mass; more common is the use of the Volcanic Explosivity Index (VEI), which is discrete and assigned on the basis of either erupted volume or eruption intensity (average mass eruption rate).
During the past 1,500 years, the Younger Oshima Group has experienced 12 major eruptions with a total volume of erupted magma of >0.6 km3 dense rock equivalent (DRE; Nakamura 1964).
Precise estimation of erupted volume and discharge rate of each eruption was conducted by Kozono et al. (2013).
The random shapes of the Ember Ridge domes are the result of erupted lava taking advantage of former ice pockets, eruptions taking place on uneven surfaces, subsidence of the domes during volcanic activity to create rubble and separation of older columnar units during more recent eruptions.
(a)–(c) are "fresh lava" (corresponding to either lava accumulated in the crater during the 2011 eruptive activity (Section 2) or vesicle-poor part of erupted magma), while (d) is "partly altered lava".
"The Grimsvotn eruption of 2011 was much larger in terms of volume of erupted material.
Ash fallout modelers make assumptions about eruption parameters, such as particle size distribution, particle density and mass of erupted material (Mastin et al. 2009).
Physical samples and field measurements of typically ephemeral deposits used to calculate mass and volume of erupted material are important to more accurate estimates of the size of an eruption.
LaMEVE contains data on Quaternary (the last 2.58 Myr as defined in Gibbard et al. 2010) explosive eruptions of magnitude (M) 4 and above, where magnitude is a function of erupted mass (Pyle 2000).
As they reached the place where the two men were seen digging in the night, a tremendous explosion echoed off the hills and the trucks vanished in a geyser of erupted earth.
