Key takeaway
A blast’s three component peaks and its frequency evidence answer a specific criterion. An averaged peak or a norm of noncoincident peaks cannot replace that record.
Name the selected ground-vibration criterion
A blast-monitor export contains one number labeled peak_velocity and a pass flag. Before using it, ask which directions were measured, how the single number was formed and which criterion the original reviewer selected. A summary can lose the component that controls the stated comparison.
Within the cited US surface-coal-mining rule, 30 CFR 816.67(d) provides different ground-vibration routes and recognizes the approved blasting plan and regulatory authority. Its maximum-PPV route applies the stated limit to each of three mutually perpendicular measurements. The alternative blasting-level chart has separate frequency-record and approved-analysis requirements. Choosing one route is part of the evidence, not an export formatting choice.
Keep the component that changes the comparison
Hypothetical example: assume the paragraph (d)(2) route, an applicable protected structure 1,000 feet from the blast, no paragraph (e) exception and no lower authority-imposed limit. Under those stipulated conditions the selected table comparison is 1.00 in/s for each component. These premises are invented; no mine, structure or blast is assessed.
The fictional monitor has the following peaks at different instants. Longitudinal and vertical remain below the selected 1.00 in/s comparison, while transverse is 1.05 in/s. The isolated transverse comparison exceeds that selected value by 0.05 in/s. Averaging the three peaks to approximately 0.817 in/s would hide it and would not apply the per-component rule.
| Invented direction | Peak particle velocity | Time of that component peak | Selected isolated comparison |
|---|---|---|---|
| Longitudinal | 0.80 in/s | 0.10 s | 0.80 ≤ 1.00 |
| Transverse | 1.05 in/s | 0.20 s | 1.05 > 1.00 |
| Vertical | 0.60 in/s | 0.15 s | 0.60 ≤ 1.00 |
A norm of three separate maxima is another derived quantity
Taking the square root of 0.80² + 1.05² + 0.60² yields 1.45 in/s. That arithmetic combines the separate peaks in the table. Because those peaks occur at different times, it does not establish the maximum instantaneous vector magnitude of the actual waveform. That calculation would need simultaneous components across the retained time history.
Keep a derived metric’s definition rather than calling every summary PPV. The completed example neither substitutes the 1.45 value for the rule’s component measurements nor treats the component average as a compliance test. A reviewer can inspect the original three channels and the specific comparison without reverse-engineering a vendor’s unexplained single-value export.
Frequency is evidence for the chosen route
The historical OSMRE manual distinguishes particle motion from the much faster propagation of a seismic wave and discusses frequency content in complex blast waveforms. It helps explain the quantities; its 1987 transmittal is not a current site authorization. Preserve the quantity name, velocity unit, waveform, sensor orientation and processing history together.
If someone instead proposes the rule’s blasting-level-chart alternative, request the required velocity and vibration-frequency record and the authority-approved predominant-frequency method. A frequency number found in a dashboard does not establish that method or approval. The example supplies neither and therefore makes no chart-based conclusion. The component comparison above cannot be silently relabeled as that different analysis. Retain the selected provision with the original reviewer’s decision; a later export should preserve which route supported that historical statement.
Finish with a bounded monitoring statement
The fictional review records one exceeded isolated component comparison under explicitly stipulated conditions. It does not determine overall blasting compliance, property damage or causation. Airblast, flyrock, protected structures, local requirements and the actual approved plan are outside this calculation. A real assessment belongs with the responsible blasting specialist and regulatory process.
For archive preparation, identify whether full waveforms, component summaries, selected criteria and review decisions survive. Link each monitor location and blast identity internally; do not expose sensitive locations or operational blasting details merely to explain the schema. Preserve distance-to-protected-structure evidence separately from the monitor’s map position. Readiness can assign missing criterion or processing evidence before anyone describes the archive as a set of verified ground-vibration decisions.