Use this geological calculation for a transparent first-pass interpretation of measured rock, soil, fluid, well, stratigraphic, isotopic, geophysical, or seismic data under an explicitly selected model.

Bulk volume

Bulk ejecta volume (tephra) in cubic meters.

Assign a Newhall-Self Volcanic Explosivity Index from bulk ejecta volume in cubic meters, including the non-log-uniform VEI 0, 1, and 2 volume thresholds. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

VEI

Volcanic Explosivity Index, integer 0 to 8.

Classification

Newhall-Self classification name.

• Classification diagrams and geochemical ratios require appropriate normalization, oxidation-state treatment, volatile basis, analytical quality, alteration screening, mineral or whole-rock context, and a composition within the method's calibration domain.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Compare independent measurements and models, retain units and analytical metadata, propagate uncertainty, and validate interpretations against logs, cores, maps, laboratory data, or field observations.

• VEI Lookup

  Newhall-Self (1982) Volcanic Explosivity Index lookup: classification name and lower-bound bulk ejecta volume for each VEI from 0 to 8; VEI 0 is below 10^4 cubic meters.

• Cooper Jacob Transmissivity Calculator

  Compute aquifer transmissivity in square meters per day from constant discharge in cubic meters per day and the semilog drawdown change per log cycle of time in meters.

• Core Porosity Helium Calculator

  Compute helium-pycnometry porosity from bulk volume and helium-measured grain volume, both in cubic centimetres.