What is Vs30 and How to Measure It (SNI 1726)
Vs30 is the basis of seismic site classification in SNI 1726. Learn how to measure it with MASW, refraction, and PS logging (OYO McSEIS-PS).
What is Vs30?
Vs30 is the average shear-wave velocity in the top 30 meters of ground. It reflects soil stiffness and is a key parameter for assessing how a site responds to earthquake shaking.
Why it matters (SNI 1726)
In earthquake-prone Indonesia, SNI 1726 uses Vs30 to classify the site class (hard rock to soft soil). This classification drives the design seismic load on buildings — making Vs30 measurement essential for safe structural and infrastructure design.
How to measure Vs30
There are several approaches: (1) MASW and seismic refraction at the surface using seismographs such as the Geometrics Geode or OYO McSEIS — fast and non-invasive; and (2) suspension PS logging inside a borehole using the OYO McSEIS-PS — providing a direct, highly accurate Vs/Vp profile to great depth, the standard for detailed site characterization.
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