Felt Radius Heuristic Log Scaling Calculator
User-parameterized log-linear felt-radius screen R = R₀·10^(kM). The default R₀=0.1 km and k=0.5 are illustrative and must be calibrated for regional attenuation, depth, and reporting conditions.
Description
User-parameterized log-linear felt-radius screen R = R₀·10^(kM). The default R₀=0.1 km and k=0.5 are illustrative and must be calibrated for regional attenuation, depth, and reporting conditions.
Felt Radius Heuristic Log Scaling Calculator is a focused tool for the following task. User-parameterized log-linear felt-radius screen R = R₀·10^(kM). The default R₀=0.1 km and k=0.5 are illustrative and must be calibrated for regional attenuation, depth, and reporting conditions. It reports R_felt, A from the values you provide rather than inventing measurements, coefficients, or professional judgment that are not part of the input.
When to use Felt Radius Heuristic Log Scaling
Use this seismology calculation to reproduce a stated convention, screen observations, or compare scenarios whose units, coordinate conventions, catalog selection, and model assumptions are known.
- M
- Required number. Event magnitude.
- R₀
- Optional number. Scaling prefactor at M=0.
- k
- Optional number. Log10 exponent per magnitude unit.
The cited overview of Fault (geology) supplies background for the terminology and domain context used by this tool.1
How Felt Radius Heuristic Log Scaling works
User-parameterized log-linear felt-radius screen R = R₀·10^(kM). The default R₀=0.1 km and k=0.5 are illustrative and must be calibrated for regional attenuation, depth, and reporting conditions. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.
- R_felt (km)
- Returned number in km. Estimated felt radius.
- A (km²)
- Returned number in km². Equivalent circular area.
Limitations and assumptions
- Earth structure, source geometry, path effects, site response, instrument response, catalog completeness, uncertainty, and the fitted range can dominate the accuracy of simplified seismic calculations.
- R₀ must be at least 0.
- k must be at least 0.
- Use finite inputs in the displayed units, preserve source measurements and assumptions, and independently verify consequential decisions.
Alternative or Complementary approaches
For analysis or hazard decisions, retain uncertainty and provenance and compare the result with waveform processing, calibrated regional models, and guidance from qualified seismologists or the responsible agency.
References
-
Fault (geology) — Wikipedia contributors
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