Passive Seismic

These kinds of surveys, based on measure and analysis of ambiental sesismic noise, that is generated from not controlled sources ( urban noise, vulcanics tremors, waves on coastline ) allow to obtain informations about stratigraphy and compactness of underground

HVSR technique needs seismic noise recordings obtained through an high dynamic seismograph with low noise, combined with a triassial velocimetric sensor properly connected to ground. Are recorded long time windows of ambiental noise as much as possible cleaned from local noise sources. These recordings allow to evaluate, through specific analysis, wich are the frequencies that can be amplified in case of earthquakes and then to attend in city structure.

Digital Seismographs:

- OYO McSeis SX; OYO McSeis 160; ECHO 2002 AMBROGEO;
- DAQlink n°serie 1121 SEISMIC SORURCE COMPANY; DAQlink n°serie 1131 SEISMIC SOURCE COMPANY

Sensors:

- OYO 3D with resonance frequency of 2 Hz;

Seismic sorces:

- Ground microtremors induced by anthropic and natural factors;

Software for data elaboration:

GeoPSY v. 2.5.0

Refraction Microtremors ( ReMi ) and Extended Spatial Auto Correlation (ESAC) are geophysical survey techniques that use the surface seismic waves of ambient noise to define the subsurface in terms of stratigraphy and compactness.
The instruments used are the same as those of the active seismic. The low frequencies that these techniques allow you to analyze, often allow raggiunere greater depths compared to traditional active seismic.

Digital Seismographs:

- OYO McSeis SX; OYO McSeis 160; ECHO 2002 AMBROGEO;
- DAQlink n°serie 1121 SEISMIC SORURCE COMPANY; DAQlink n°serie 1131 SEISMIC SOURCE COMPANY



- geophones with 4,5 Hz frequency
- seismic wires 'till 150m;

Seismic sources:

- Ground microtremors induced by anthropic and natural factors;

Software for data elaboration:

SeisImager/2D, GeoPSY v. 2.5.0