ISO 24057:2022

Overview - ISO 24057:2022 (Array measurement of microtremors)

ISO 24057:2022 specifies requirements for planning, performing and reporting array measurement of microtremors to estimate a 1D shear wave (S‑wave) velocity profile. Focused on geotechnical applications, the standard covers equipment, survey procedure, data analysis and reporting for passive surface‑wave measurements using vertical ground vibration processed on the basis of the fundamental mode of Rayleigh waves. The method is a non‑destructive testing technique using an array of sensors deployed on the ground surface.

Key topics and technical requirements

• Equipment requirements: sensor selection (accelerometers/velocity meters), amplifiers, data loggers (with GNSS time), time calibration, distance/location instruments and protective products.
• Survey procedure: desk study, array design, sensor setting, huddle test (sensor consistency check), recording protocols and field quality control.
• Data analysis:
  • Phase velocity analysis to derive dispersion curves (phase velocity vs frequency).
  • Inversion analysis to convert dispersion curves into a 1D S‑wave velocity profile.
  • Assessment and reporting of uncertainty in phase velocity and S‑wave velocity results.
• Reporting: standardized field and analysis reports, data storage and documentation to support reproducibility.
• Scope limitations: explicitly addresses only vertical‑component microtremors and the fundamental Rayleigh mode. Analysis of higher Rayleigh modes and Love waves is out of scope.

Practical applications and intended users

ISO 24057:2022 is intended for:

• Infrastructure administrators (public and private), building constructors and house builders
• Geotechnical and seismic consultants, environmental engineers and survey contractors
• Academia and research institutions

Practical uses include:

• Site characterization for foundation design and construction
• Stability assessment and seismic ground‑motion evaluation
• Assessment of soil liquefaction potential
• Rapid, low‑impact investigations as an alternative or complement to boreholes, CPT/SPT and active source methods (e.g., sledgehammer)

The standard highlights that depth sensitivity depends on observed surface‑wave wavelengths and that combining array microtremor data with borehole or sounding information reduces inversion uncertainty. It also notes the value of H/V spectral ratio and active methods for improving shallow‑depth resolution.

Related standards and guidance

• Prepared by ISO/TC 182 (Geotechnics); users should consult national annexes and local geotechnical practice.
• Use in conjunction with borehole and sounding standards (CPT, SPT) and geophysical method guidance for comprehensive site characterization.

Keywords: ISO 24057:2022, array measurement of microtremors, shear wave velocity profile, S‑wave velocity, Rayleigh waves, geotechnics, passive seismic, dispersion curve, phase velocity, huddle test.