Application Guide
Seismic Equipment for Site Characterisation (Refraction, MASW & HVSR)
Seismic methods measure the stiffness of the ground directly — depth to bedrock, rippability, shear-wave velocity profiles and Vs30 for seismic design.
Engineering seismology is the geophysics geotechnical engineers rely on most, because seismic velocities relate directly to ground stiffness. Refraction maps layers and rockhead; MASW derives shear-wave velocity profiles from surface waves; HVSR uses ambient vibration recorded by a single three-component sensor to estimate the resonance frequency and sediment thickness.
Modern projects increasingly combine active surveys with cable-free nodes for passive seismic, which makes long arrays and urban sites far easier to deploy.
Methods Compared
| Method | Detects | Typical Depth | Limitations |
|---|---|---|---|
| Seismic refraction / tomography | Layer boundaries, depth to bedrock, rippability | Tens of metres | Needs velocity to increase with depth |
| MASW / surface-wave methods | Shear-wave velocity (Vs) profiles, Vs30 | Up to ~30 m (active), deeper (passive) | 1D/2D averages; needs care in complex geology |
| HVSR (ambient noise) | Site resonance frequency, sediment thickness | Shallow to hundreds of metres | Single-station estimate; needs calibration for depth |
| Seismic reflection | Detailed stratigraphy and structure | Tens to hundreds of metres | More demanding acquisition and processing |
Depths are typical field values — actual performance depends on ground conditions, target size and survey design.
Cabled seismographs vs nodes
Cabled multichannel seismographs remain efficient for refraction and MASW lines on open ground. Autonomous nodes remove cables entirely — ideal for urban sites, long passive arrays and HVSR grids. Short-period and long-period seismometers extend HVSR to deeper basins.
Recommended Instruments
A selection from our catalog. We source many more models — tell us what you need.
Which Condition Tier?
Seismographs and geophones are durable, so Refurbished and Absolute Certified systems are a strong-value choice; legacy recorders and geophone strings in Surplus condition are useful to extend channel counts or for teaching.
See the condition tier guide for what New, Refurbished, Absolute Certified and Surplus each include, or the industries overview for related sectors.
Frequently Asked Questions
What is MASW used for?
MASW (multichannel analysis of surface waves) estimates the shear-wave velocity profile of the ground, used for Vs30 site classification, ground stiffness and compaction assessment.
What equipment do I need for HVSR?
A three-component seismometer or nodal sensor with a suitable low natural frequency (1 Hz or lower for most sites) and a digitiser/recorder.
Can I use exploration geophones for MASW?
Yes, but low-frequency vertical geophones (4.5 Hz or lower) are preferred for MASW so that longer wavelengths — and greater depths — are recorded.
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