Calculator Inputs
Use the fields below to estimate a seismic number from observed wave amplitude and optional correction terms.
Plotly Graph
The chart shows how the calculated number changes as observed amplitude changes while keeping the other selected inputs fixed.
Example Data Table
These sample values use a distance-corrected setup with Aref = 1 µm, dref = 100 km, α = 1.11, β = 0.00189, and station correction = 0.12.
| Observed Amplitude (µm) | Distance (km) | Frequency (Hz) | Wave Speed (m/s) | Estimated Number |
|---|---|---|---|---|
| 120 | 80 | 2.4 | 2800 | 2.054 |
| 350 | 120 | 3.5 | 3200 | 2.790 |
| 900 | 180 | 4.1 | 3600 | 3.509 |
| 2500 | 250 | 5.0 | 4200 | 4.243 |
Formula Used
1) Pure amplitude ratio number
N0 = log10(A / Aref)
2) Distance-corrected seismic number
N = log10(A / Aref) + α log10(d / dref) + β(d - dref) + S + C
Here, A is observed amplitude, Aref is reference amplitude, d is epicentral distance, dref is reference distance, α and β are attenuation terms, S is station correction, and C is a calibration constant.
3) Derived wave relations
T = 1 / f, λ = v / f, k = 2π / λ = 2πf / v
T is period, f is frequency, λ is wavelength, v is wave speed, and k is wavenumber. Regional observatories may use different correction coefficients, so this calculator is best used as a configurable educational and engineering tool.
How to Use This Calculator
- Choose whether you want a pure amplitude ratio number or a distance-corrected number.
- Enter the observed amplitude and select its unit.
- Enter the reference amplitude, distance values, and any correction terms you want to apply.
- Add wave frequency and wave speed to calculate period, wavelength, and wavenumber.
- Press Calculate to show the result above the form, review the graph, and export CSV or PDF files.
FAQs
1) What does this calculator estimate?
It estimates a logarithmic seismic number from measured wave amplitude. You can use a pure amplitude ratio or a distance-corrected form with attenuation, station correction, and calibration terms to approximate local-magnitude-style readings.
2) The number of cycles of a wave that passes a stationary point in one second is called its what?
It is called frequency. Frequency tells you how many complete oscillations pass a fixed point each second, and its standard unit is hertz, or cycles per second.
3) What is the number of wave cycles passing a point per unit of time?
That quantity is also frequency. It measures how quickly the wave repeats in time and is commonly written in hertz, which means one cycle per second.
4) What is wave number?
Wave number describes how rapidly phase changes through space. It equals 2π divided by wavelength in radians per meter, or one over wavelength when using cycles per meter.
5) This is the number of complete movements of a wave per second.
That quantity is frequency. A higher frequency means more complete vibrations each second and a shorter period, because period equals the reciprocal of frequency.
6) Why does distance matter in seismic amplitude calculations?
Amplitude weakens as seismic waves spread and lose energy. Distance corrections reduce unfair differences between nearby and distant recordings, making the reported number more comparable across stations.
7) Which amplitude units can I use?
Use nanometers, micrometers, millimeters, centimeters, or meters. The calculator converts units internally before applying logarithms, so the final number stays consistent when your observed and reference amplitudes are entered correctly.
8) Is frequency the same as wave number?
No. Frequency measures oscillations over time, while wave number measures oscillations over distance. They are linked through wave speed, because wavenumber equals 2πf divided by velocity.