Geology Tephra Fall Thickness Exponential Decay Calculator
Declared fitted one-dimensional exponential tephra thicknessT0exp(−x/L). Actual applicable transect and independently fit T0, Lrequired; no eruption forecast, total volume or fallout hazard approval.
Description
An exponential tephra-thickness model relates downwind distance to fitted reference thickness and decay length.
An exponential tephra-thickness model relates downwind distance to fitted reference thickness and decay length.1
Its parameters describe an adopted deposit scenario rather than an eruption forecast. Use this tool to calculate the stated observation or conditional model from supplied measurements.
When to use Geology Tephra Fall Thickness Exponential Decay Calculator
Use this tool to calculate the stated observation or conditional model from supplied measurements. Establish the sample and coordinate basis, matching units, calibration source and applicable model assumptions.
How to use Geology Tephra Fall Thickness Exponential Decay Calculator and understand its results
- Establish the sample and coordinate basis, matching units, calibration source and applicable model assumptions.
- Enter actualDownwindDistanceMeters, callerFittedReferenceThicknessMeters, callerFittedDecayLengthMeters, using the field meanings and rules below, then run the tool.
- Read result.conditionalExponentialTephraThicknessMeters. Interpret each field using the units, signs and evidence rules below.
- If input validation fails, correct the reported field and run again. Before applying a successful result, check the stated reference scope, units, assumptions and any retained unknown evidence.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| actualDownwindDistanceMeters | Actual downwind distance meters | number | Required |
| callerFittedReferenceThicknessMeters | Caller fitted reference thickness meters | number | Required |
| callerFittedDecayLengthMeters | Caller fitted decay length meters | number | Required |
Require nonnegative downwind distance and reference thickness, with positive decay length in meters. Multiply thickness by exp(−distance/decayLength). The exponential must remain finite and nonzero; exact exponential underflow fails even when reference thickness is zero. No calibration fitting or deposit-area integration occurs.
thicknessMeters=T0Meters×exp(−distanceMeters/decayLengthMeters) Apply the field units and exact ordering, boundary and evidence rules above.
| Output field | Meaning | Value type |
|---|---|---|
| result | Structured result containing the calculation or selected reference fields below | object |
| result.conditionalExponentialTephraThicknessMeters | Conditional Exponential Tephra Thickness Meters; use the units, sign convention and calculation stated above | number |
{
"input": {
"actualDownwindDistanceMeters": 1,
"callerFittedReferenceThicknessMeters": 10,
"callerFittedDecayLengthMeters": 2
},
"output": {
"result": {
"conditionalExponentialTephraThicknessMeters": 6.065306597126334
}
}
}Limitations and assumptions
Its parameters describe an adopted deposit scenario rather than an eruption forecast. Results depend on the independently established measurement basis and the exact model assumptions above.
Every listed input requires an explicit value. Unexpected fields, incorrect value types, nonfinite numbers and sparse numeric arrays fail validation; tool-specific bounds and alignment rules apply as described above. Extremely large inputs or outputs can also be rejected. An input error is distinct from a successful calculation that reports a false comparison or retains unknown evidence.
Alternative or Complementary methods
Use Geology Pyroclastic Flow Runout Calculator to examine a related aspect: Pyroclastic-flow runout depends on topography and a qualified flow model.
Use Geology Lava Flow Length Jeffreys Calculator where its separate inputs and scope apply: Jeffreys-related lava-flow interpretation depends on the adopted geometry and rheological model.
References
Similar or alternative tools
- Geology Pyroclastic Flow Runout Calculator
Pyroclastic-flow runout depends on topography and a qualified flow model.
- Geology Lava Flow Length Jeffreys Calculator
Jeffreys-related lava-flow interpretation depends on the adopted geometry and rheological model.