Microtremors=Nakamura method

[Mccoy]

Dear all,
I wonder if the Nakamura geophysical method to measure the microtremor field in a site is of common use in other places of the world. Here in Italy it's pretty popular and I myself am a regular user.
MAin goal is the definition of the resonance period of the site, with a quantitative measure of its frequency (or frequencies if multiple resonance exists) and a qualitative index of its amplitude.

A very brief reference can be found in wikipedia

http://en.wikipedia.org/wiki/Microtremor

 

[moe333]

Mccoy,
ReMi is commonly used in California to estimate VS30 for seismic site class.

 

[Mccoy]

Hi moe, Remi is another microtremors method but it is an array method with an output similar to the MASW surveys:

The nakamura or HVSR method is a single-station survey with a typical output like this:

where the peak in the frequency domain corresponds to the resonance frequency of the site, you can sometimes invert the signal to build a VS profile but this is not the main purpose of the method, which is to find the resonant frequencies and try to avoid to build a structure with the same frequency (double-resonance ).