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.

VEI

Volcanic Explosivity Index, integer 0 to 8.

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. 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]

Classification

Newhall-Self classification name.

Min volume

Lower-bound bulk ejecta volume in cubic meters (0 for VEI 0, which is under 10^4).

• 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.

• Volcanic Explosivity Index Calculator

  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.

• Seismic Reflection Coefficient Calculator

  Normal-incidence P-wave reflection coefficient R = (Z2 - Z1) / (Z2 + Z1) from layer velocities in meters per second and bulk densities in kilograms per cubic meter, where Z is acoustic impedance.

• Core Porosity Helium Calculator

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