Caldera Collapse Volume Ring Fault

Calculate annular caldera subsidence geometry and independently supplied fill reduction; collapse void is not automatically erupted magma withdrawal and no ring-fault displacement model or mapping.

Description

Caldera subsidence can occupy an annulus around an uncollapsed core.

Caldera subsidence can occupy an annulus around an uncollapsed core. Geometric void volume differs from the amount of magma erupted.

Calculate annular caldera subsidence geometry and independently supplied fill reduction; collapse void is not automatically erupted magma withdrawal and no ring-fault displacement model or mapping.

When to use Caldera Collapse Volume Ring Fault

Use this tool to calculate annular caldera subsidence geometry and independently supplied fill reduction; collapse void is not automatically erupted magma withdrawal and no ring-fault displacement model or mapping.

Gather the relevant observations and fitted model parameters. Use the stated units and time basis; keep paired observations aligned.

How to use Caldera Collapse Volume Ring Fault and understand its results

Gather the relevant observations and fitted model parameters. Use the stated units and time basis; keep paired observations aligned.
Enter outerCollapseRadiusM, innerUncollapsedRadiusM, meanSubsidenceM, subsidedFillFraction using the field table and calculation rules, then run the tool.
Read annularCollapseVolumeM3, unfilledCollapseVolumeM3. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
outerCollapseRadiusM	Outer collapse radius m	number	Required
innerUncollapsedRadiusM	Inner uncollapsed radius m	number	Required
meanSubsidenceM	Mean subsidence m	number	Required
subsidedFillFraction	Subsided fill fraction	number	Required

Use positive outer radius, nonnegative inner radius strictly smaller than outer, nonnegative subsidence and fill fraction in [0,1]. Calculate annular volume and multiply by one minus fill for unfilled volume.^[1]

collapse volume = π(outer² − inner²) × mean subsidence

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
annularCollapseVolumeM3	Annular collapse volume m3	number
unfilledCollapseVolumeM3	Unfilled collapse volume m3	number

json

{
  "input": {
    "outerCollapseRadiusM": 10,
    "innerUncollapsedRadiusM": 5,
    "meanSubsidenceM": 2,
    "subsidedFillFraction": 0.2
  },
  "output": {
    "annularCollapseVolumeM3": 471.23889803846896,
    "unfilledCollapseVolumeM3": 376.9911184307752
  }
}

Limitations and assumptions

Uniform subsidence and supplied fill are assumed; no ring-fault mapping or withdrawal inference is made.

Numbers and computed results must be finite; overflow produces an error. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.

Alternative or Complementary methods

Use Ring Dike Thickness Estimate: Invert a full circular vertical ring-dike volume to radial thickness with a cancellation-safe annulus inversion; assumes uniform extent and complete ring, not a fault-stress estimate. For a complementary task, use DRE To Tephra Volume Conversion: Convert declared whole-deposit DRE to bulk tephra volume by mass conservation, splitting supplied juvenile/lithic mass share; packing, vesicles and interclast pores are already embodied in measured bulk density.

References

Caldera Collapse Volume Ring Fault — tool.io

Similar or alternative tools

Ring Dike Thickness Estimate
Invert a full circular vertical ring-dike volume to radial thickness with a cancellation-safe annulus inversion; assumes uniform extent and complete ring, not a fault-stress estimate.
DRE To Tephra Volume Conversion
Convert declared whole-deposit DRE to bulk tephra volume by mass conservation, splitting supplied juvenile/lithic mass share; packing, vesicles and interclast pores are already embodied in measured bulk density.