1. ET: micro-earthquakes and seismic noise
ET-ILIAS_GWA Joint Meeting
Cascina, 25th November 2008
ET: micro-earthquakes and
seismic noise
Gaetano De Luca and Wolfango Plastino
National Institute of Nuclear Physics - Gran Sasso National Laboratory – ERMES Experiment
Department of Physics “Edoardo Amaldi” – University of Roma Tre

2. G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise
ET-ILIAS_GWA Joint Meeting
Cascina, 25th November 2008
Introduction
Estimation of seismic risk assessment
Source and attenuation effects at local scale
Seismic ground motion in an underground environment (Gran Sasso National Laboratory – National Institute of Nuclear Physics)
G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise

3. G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise
ET-ILIAS_GWA Joint Meeting
Cascina, 25th November 2008
Lazaro Cardenas
G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise

4. G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise
ET-ILIAS_GWA Joint Meeting
Cascina, 25th November 2008
G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise

5. G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise
ET-ILIAS_GWA Joint Meeting
Cascina, 25th November 2008
G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise

6. G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise
ET-ILIAS_GWA Joint Meeting
Cascina, 25th November 2008
G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise

7. G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise
ET-ILIAS_GWA Joint Meeting
Cascina, 25th November 2008
26th September, 1997 – 00:33 UT
TIME (s)
26th September, 1997 – 00:33 UT
TIME (s)
G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise

8. G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise
ET-ILIAS_GWA Joint Meeting
Cascina, 25th November 2008
The spectral ratio method
Oij - Fourier spectrum of a seismic signal
Sij - source
Pij - path
Iij - instrument
Rij - site
where f is the frequency, j indicates the earthquake and i the station
G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise

9. G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise
ET-ILIAS_GWA Joint Meeting
Cascina, 25th November 2008
The Nakamura’s method
It consists in the evaluation of the spectral ratio between the horizontal and vertical component (H/V)
The Coda-wave method
Considering the Coda-waves in a time window centered at an elapsed time, measured from the origin time, which is at least twice the travel time of the S-waves, it is possible to disregard the effects of source radiation pattern and the travel path and to estimate the site transfer function for shear waves
G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise

10. G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise
ET-ILIAS_GWA Joint Meeting
Cascina, 25th November 2008
Spectral ratio at AQPK,
CASC, GDIF, STAZ
sites
SPECTRAL RATIO
FREQUENCY (Hz)
CASC
GDIF
SANG-MUSE
AQPK
STAZ
G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise

11. ET-ILIAS_GWA Joint Meeting
Cascina, 25th November 2008
H-V ratios at AQPK,
CASC, GDIF, STAZ and SANG-MUSE
sites
CASC
GDIF
SANG-MUSE
AQPK
STAZ
G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise

12. G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise
ET-ILIAS_GWA Joint Meeting
Cascina, 25th November 2008
G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise

13. G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise
ET-ILIAS_GWA Joint Meeting
Cascina, 25th November 2008
G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise

14. G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise
ET-ILIAS_GWA Joint Meeting
Cascina, 25th November 2008
[De Luca et al. (1998), Site response study in Abruzzo (central Italy): underground array versus surface stations , Journal of Seismology]
G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise

15. G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise
ET-ILIAS_GWA Joint Meeting
Cascina, 25th November 2008
[De Luca et al. (1998), Site response study in Abruzzo (central Italy): underground array versus surface stations , Journal of Seismology]
G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise

16. G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise
ET-ILIAS_GWA Joint Meeting
Cascina, 25th November 2008
Underground array results for S-waves (bold lines) and noise (dashed lines): (a) spectral ratios between horizontal and vertical components; (b) spectral ratios between parallel (to the tunnel) and vertical components; (c) spectral ratios between transversal (to the tunnel) and vertical components
[De Luca et al. (1998), Site response study in Abruzzo (central Italy): underground array versus surface stations , Journal of Seismology]
G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise

17. G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise
ET-ILIAS_GWA Joint Meeting
Cascina, 25th November 2008
The observation of several seismograms indicates that the North-South component of motion is larger than East-West component, independently on source location and mechanism
[De Luca et al. (1998), Site response study in Abruzzo (central Italy): underground array versus surface stations , Journal of Seismology]
G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise

18. G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise
ET-ILIAS_GWA Joint Meeting
Cascina, 25th November 2008
LATITUDE NORTH (°)
LONGITUDE EAST (°)
© ERMES – INFN Roma Tre and LNGS
G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise

19. G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise
ET-ILIAS_GWA Joint Meeting
Cascina, 25th November 2008
Very slow-moving crustal strain disturbances
Bella et al. (1990) – Tectonophysics
Aquifer induced seismicity in the central Italy
Bella et al. (1998) – Pure and Applied Geophysics
Diffusion in porous media with memory
Caputo and Plastino (2004) – Geophysical Journal International
G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise

20. G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise
ET-ILIAS_GWA Joint Meeting
Cascina, 25th November 2008
Conclusions
The obtained results confirm that the general trend of the spectral ratios for S-waves is quite uniform at different stations: almost flat for the entire band of frequency considered. As compared to the external stations there is still an amplification factor, in the frequency band 1–10 Hz.
The comparison of the signals observed at the surface stations and the underground array show that free surface effects and mostly the resonance due to surface layers influence significantly the spectral shape, particularly for events at distances smaller than about 50 km.
The observation of several seismograms indicates that the North-South component of motion is larger than East-West component, independently on source location and mechanism.
G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise

21. G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise
ET-ILIAS_GWA Joint Meeting
Cascina, 25th November 2008
G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise

22. G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise
ET-ILIAS_GWA Joint Meeting
Cascina, 25th November 2008
cm/s2
G. De Luca and W. Plastino – ET: micro-earthquakes and seismic noise