Microtremor Array Measurements (MAM)

Microtremor Array Measurements (MAM)

GeoPhysi is at the forefront of Microtremor Array Measurements (MAM), a specialized geophysical technique used to assess the subsurface shear wave velocity structure. This method is particularly effective for seismic site characterization, soil classification, and earthquake hazard assessment. MAM is non-invasive and utilizes ambient seismic noise, making it ideal for urban areas where traditional seismic methods may be challenging to implement.

MAM involves deploying an array of sensors on the ground surface to record microtremors—low-amplitude vibrations caused by natural and human activities. By analyzing the dispersion of these surface waves, GeoPhysi can accurately determine the shear wave velocity profile of the subsurface. This information is crucial for understanding the dynamic behavior of soils and rocks, which is essential for designing earthquake-resistant structures and conducting seismic risk assessments.

One of the key advantages of MAM is its ability to provide reliable data in areas with low seismicity or where active seismic sources are impractical. This method is also cost-effective, easy to deploy, and can be conducted without disturbing the site or surrounding activities.

At GeoPhysi, we leverage our expertise and advanced technology to deliver precise and reliable MAM surveys. Our team of geophysicists is dedicated to providing accurate data that supports informed decision-making for engineering and construction projects. We tailor our surveys to meet the specific needs of each project, ensuring the best possible outcomes.

Choose GeoPhysi for your Microtremor Survey needs and experience the benefits of working with a leader in geophysical surveying. Contact us today to learn more about how we can support your project with our expert services.

Technical reference · MAM

What is Microtremor Array Measurement?

Microtremor Array Measurement (MAM) is a passive surface-wave method that uses ambient ground vibration recorded by an array of sensors to estimate subsurface shear-wave velocity structure. The result supports seismic site characterization and engineering interpretation; it is a measurement method, not a standalone ground model or a substitute for site-specific validation.

MAM is most useful when a non-invasive survey is preferred, active sources are impractical, or the project needs a broader view of near-surface stiffness before selecting complementary investigation methods.

What MAM measures and how engineers use it

MAM produces a surface-wave dispersion response that can be interpreted to estimate a shear-wave velocity profile. Engineers may use that information to support site characterization, preliminary ground models, seismic response assessment and the selection of complementary investigations.

• Useful output: a velocity-versus-depth interpretation with documented assumptions and uncertainty.
• Field decision: array layout, access, ambient noise and nearby activity affect usable bandwidth and data quality.
• Engineering decision: combine MAM with borehole, refraction, MASW, ERT or other evidence when the project requires independent constraints.

The appropriate array geometry and survey extent depend on the target depth, required resolution, site access and the frequency content of the recorded noise; no single layout is suitable for every site.

Limitations and selection criteria

MAM interpretation is affected by ambient noise, array geometry, lateral ground variation, mode identification, inversion assumptions and the available frequency range. It should not be presented as a precise material profile without quality checks and supporting evidence.

Method selection at a high level

Method	Typical strength	When to consider another method
MAM	Passive, non-invasive surface-wave characterization	Need stronger active-source control or independent depth constraints
MASW	Controlled active or passive surface-wave acquisition	Access, noise or target geometry makes surface-wave acquisition unsuitable
Seismic refraction	Travel-time constraints and identifiable refractors	Velocity inversions or ambiguous interfaces limit refraction interpretation

For related methods, see MASW, surface-wave seismic survey and the Technical Hub.

QA/QC, interpretation and responsibility

A defensible MAM result should document sensor layout, acquisition conditions, usable frequency range, processing choices, dispersion-curve picking, inversion assumptions and uncertainty. Field notes and repeatability checks help distinguish a stable engineering signal from site-specific noise.

Questions to record before using the result

• Was the array geometry appropriate for the target and site access?
• Were nearby traffic, machinery or transient sources identified?
• Is the interpretation consistent with borehole, refraction or other independent evidence?
• Are the limitations and uncertainty visible in the final report?

Page responsibility: GEOOE Technical Center. Technical claims should be checked against the project brief, field records and the responsible engineer’s review before use in design or safety decisions.