|Criteria for applying data quality indicators to volume data|
|VOLUME DATA QUALITY INDICATOR|
|0||No isopach map or evidence to support cited volume OR assumed value.|
|1||Simple isopach map or thickness data (< 10 measurements) OR volume calculation with no methodology given OR volume derived from method other than isopach map (e.g. size of caldera; VEI estimate; duration and intensity of column heights).|
|2||Isopach map drawn from >10 and <30 measured thicknesses with calculation method described.|
|3||Isopach map drawn from >30 measured thicknesses with calculation method described.|
There is no standardised method for constructing isopach maps from thickness data and several methods of extrapolation beyond the areas with data have been devised. The diversity of methods means there can be significant volume differences even with the same datasets when different methods are applied. Volumes are reported directly from sources using whichever method they applied, but preference is given to those calculated using the Pyle or Fierstein methods (Pyle 2000, Fierstein and Nathenson 1992). However, there are other methods and pre-1989 literature with various ways of integrating the volume from isopach maps. Some volumes include pyroclastic flow deposits where isopach maps are not necessarily readily drawn. Here the number of thickness measurements as above is used to assign a volume data quality indicator.
Crosweller et al. Journal of Applied Volcanology 2012 1:4 doi:10.1186/2191-5040-1-4