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Arch dam and valley site under seismic instrumentation

HVSR — Seismic site characterization

HVSR site characterization.

Included in Core, Pro, and Ultimate. Analyze horizontal-to-vertical spectral ratios, review SESAME curve and peak criteria, and inspect directional variation and peak-frequency stability.

Buy now See the SESAME criteria
0CRITERIA SESAME reliability + clarity checks, itemized pass/fail. f₀STABILITY Fundamental frequency tracked across windows and azimuths. H/VDIRECTIONAL Azimuthal H/V for directional site response. .V2+ SMC · SAF Strong-motion formats ingested natively.
SESAME, itemized

SESAME criteria.

The SESAME Guidelines (2004) provide criteria for H/V curve reliability and peak clarity. Review the measured values against the individual thresholds below.

Curve reliability 3 criteria — all required
  1. The peak frequency exceeds ten cycles per window: f₀ > 10 / L​w — a minimum cycle count per window.
  2. A significant cycle count across the whole record: n​c(f₀) > 200 — a minimum total cycle count.
  3. Bounded amplitude scatter near the peak: σ​A(f) < 2 over 0.5 f₀–2 f₀ (relaxed to < 3 for f₀ below 0.5 Hz).
Peak clarity 6 criteria — at least 5 required
  1. A trough below the peak: some f⁻ in [f₀/4, f₀] with amplitude under A₀/2.
  2. A trough above the peak: some f⁺ in [f₀, 4 f₀] with amplitude under A₀/2.
  3. Peak amplitude: A₀ > 2.
  4. The peak stays put under its own uncertainty band: f​peak[A(f) ± σ​A(f)] = f₀ ± 5%.
  5. Frequency scatter within the SESAME bound: σ​f < ε(f₀), with the threshold taken from the guideline's frequency class.
  6. Amplitude scatter within the SESAME bound: σ​A(f₀) < θ(f₀), likewise class-dependent.

Lw is the window length; f₀ is the selected peak frequency. SESAME criteria support interpretation of the H/V curve; passing them alone does not establish site safety or a design amplification factor.

Beyond the single curve

Directional variation
and peak stability.

DIRECTIONAL H/V

Directional H/V

Compare H/V curves across azimuths to inspect direction-dependent peaks.

  • AzimuthalH/V evaluated across rotation angles, not just the geometric mean.
  • AnisotropyDirectional peaks flagged and visualized for the report.
f₀ STABILITY

Peak frequency over time

Track the selected peak across time windows and inspect scatter, drift, and inconsistent windows before reporting f₀.

  • WindowedPer-window peak tracking across the full record.
  • ScatterDispersion shown against the SESAME bounds, alongside the mean.
The data you actually have

Measurement formats.

Import supported strong-motion and SAF files alongside ambient vibration measurements. Review channel metadata and units before analysis.

.V2 / .V2CProcessed strong-motion records, read as delivered by the network.
.SMCStrong-motion CD format, ingested with its station metadata.
SAFSimple ASCII Format — import and export, for interchange with the ambient-vibration ecosystem.
AmbientThe same session handles TDMS, CSV/TXT, and XLSX ambient data — site and structure side by side.
One instrument

Compare site and
structural frequencies.

Review structural modal frequencies alongside the H/V peak frequency. Interpretation requires the measurement context, site information, and engineering judgement.

SCREENING

Frequency comparison

Compare identified structural frequencies with the selected H/V peak.

f₁ vs f₀ ⋅ one view
MICROZONATION

Site investigations

Retain H/V curves, window selection, and criteria results as evidence for further site interpretation.

SESAME ⋅ itemized
HERITAGE

Heritage surveys

Combine ambient vibration analysis with H/V measurements when both are part of the survey scope.

structure + site ⋅ one visit

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Choose your Modal Master edition.

Compare Core, Pro, and Ultimate to find the features you need. Contact us for edition guidance or technical support.

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Technical evaluations · Edition guidance · Licensing enquiries

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