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.

a_i (m/s²)

Required list in m/s². Raw acceleration samples.

f_tail

Optional number. Tail fraction used to fit the baseline line.

The cited overview of Seismology supplies background for the terminology and domain context used by this tool.^[1]

Remove linear baseline drift fitted on the record tail and report the corrected peak. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

PGA_corr (m/s²)

Returned number in m/s². Peak absolute acceleration after detrending.

b₀ (m/s²)

Returned number in m/s². Baseline offset removed at sample zero.

b₁ (m/s²/sample)

Returned number in m/s²/sample. Linear drift removed per sample.

• 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.
• f_tail must be at least 0.1.
• f_tail must be no greater than 0.5.
• Use finite inputs in the displayed units, preserve source measurements and assumptions, and independently verify consequential decisions.

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.

• Clock Drift PPM Linear Regression Calculator

  Least-squares drift rate in parts-per-million from timing offsets versus elapsed days.

• Brune Displacement Spectrum Peak Frequency Note

  For the Brune model, displacement amplitude peaks exactly at the corner frequency.

• Catalog Depth Histogram Binner

  Bin hypocentral depths into fixed-width bins with an out-of-range tail count.