Effects of Surface Geology on Seismic Ground Motion Deduced from Ambient-Noise Measurements, in the Town of Avellino, Irpinia Region (Italy)

The effects of surface geology on ground motion
provide an important tool in seismic hazard studies. It is well
known that the presence of soft sediments can cause amplification
of the ground motion at the surface, particularly when there is a
sharp impedance contrast at shallow depth. The town of Avellino is
located in an area characterised by high seismicity in Italy, about
30 km from the epicentre of the 23 November 1980, Irpinia
earthquake (M = 6.9). No earthquake recordings are available in
the area. The local geology is characterised by strong heterogeneity,
with impedance contrasts at depth. We present the results
from seismic noise measurements carried out in the urban area of
Avellino to evaluate the effects of local geology on the seismic
ground motion. We computed the horizontal-to-vertical (H/V)
noise spectral ratios at 16 selected sites in this urban area for which
drilling data are available within the first 40 m of depth. A Rayleigh
wave inversion technique using the peak frequencies of the
noise H/V spectral ratios is then presented for estimating Vs
models, assuming that the thicknesses of the shallow soil layers are
known. The results show a good correspondence between experimental
and theoretical peak frequencies, which are interpreted in
terms of sediment resonance. For one site, which is characterised
by a broad peak in the horizontal-to-vertical spectral-ratio curve,
simple one-dimensional modelling is not representative of the
resonance effects. Consistent variations in peak amplitudes are seen
among the sites. A site classification based on shear-wave velocity
characteristics, in terms of Vs30, cannot explain these data. The
differences observed are better correlated to the impedance contrast
between the sediments and basement. A more detailed investigation
of the physical parameters of the subsoil structure, together with
earthquake data, are desirable for future research, to confirm these
data in terms of site response.

ARAI, H., and TOKIMATSU, K. (2004), S-wave velocity profiling by
inversion of microtremor H/V spectrum, Bull. Seism. Soc. Am.,
94, 53–63.
BARD, P.Y. (1999), Microtremor measurements: a tool for site
effect estimation?, Proc of the 2nd Int. Symp. on Effects of
Surface Geology on Seismic Motion, Yokohama, Japan, 1-3
December, 3, 1251–1282.
BONNEFOY-CLAUDET, S., CORNOU, C., BARD, P.Y., and COTTON, F.
(2006), H/V ratio: a tool for site effects evaluation. Results from
1-D noise simulations, Geophys. J. Int., 167, 827-837.
BONNEFOY-CLAUDET, S., KO¨ HLER, A., CORNOU, C., WATHELET, M.,
and BARD, P.Y. (2008), Effects of Love waves on microtremor
H/V ratio, Bull. Seism. Soc. Am., 98, 288–300.
BONNEFOY-CLAUDET, S., BAIZE, S., BONILLA, L.F., BERGE-THIERRY,
C., PASTEN, C., CAMPOS, J., VOLANT, P., and VERUGO, R. (2009),
Site effect evaluation in the basin of Santiago de Chile using
ambient noise measurements, Geophys. J. Int., 176, 925-937.BORCHERDT, R.D., WENTWORTH, C.M., JANSSEN, A., FUMAL, T., and
GIBBS, J. (1991), Methodology for predictive GIS mapping of
special study zone for strong ground motion in the San Francisco
Bay region, CA., In Proc. Fourth Int. Cont. on Seismic Zonation,
Earthquake Engineering Research Institute, Oakland, California,
545–552.
CANDELA, M., and VIGGIANI, C. (1988), The effects of the Irpinia
earthquake in the ancient centre of Avellino, Italy, Proc. Inter.
Symp. IAEG, Athens, Greece, 1988.
CASTELLARO, S., and MULARGIA, F. and ROSSI P.M. (2008), VS30:
proxy for seismic amplification?, Seism. Res. Lett. 79, 540–542.
CASTELLARO, S., and MULARGIA, F. (2010), How far from a building
does the ground-motion free-field start?, Bull. Seism. Soc. Am.,
100, 2080–2094.
CLARK, S.P. (1966), Handbook of physical constants, Geol. Soc.
Am., Mem., 97.
COCCO, M, CHIARABBA, C., DI BONA, M., SELVAGGI, G., MARGHERITI,
L., FREPOLI, A., LUCENTE, F.P., BASILI, A., JONGMANS, D., and
CAMPILLO, M. (1999), The April 1996 Irpinia seismic sequence:
evidence for fault interaction, Journ. Seismol., 3, 105–117.
DI GIULIO, G., CORNOU, C., OHRNBERGER, M., WATHELET, M., and
ROVELLI, A. (2006), Deriving wavefield characteristics and
shear-velocity profiles from two-dimensional small-aperture
arrays analysis of ambient vibrations in a small-size alluvial
basin, Colfiorito, Italy, Bull. Seism. Soc. Am., 96, 1915–1933.
DI GIULIO, G., IMPROTA, L., CALDERONI, G., and ROVELLI, A. (2008),
A study of the seismic response of the city of Benevento (southern
Italy) through a combined analysis of seismological and geological
data, Engin. Geol., 97, 146–170.
DI NOCERA, S., MATANO, F., PESCATORE, T., PINTO, F., QUARANTIELLO,
R., SENATORE, M.R., and TORRE, M. (2006), Schema geologico del
transetto Monti Picentini orientali—Monti della Daunia meridionali:
unita` stratigrafiche ed evoluzione tettonica del settore
esterno dell’Appennino meridionale, Boll. Soc. Geol. It., 125,
39–58.
FA¨ H, D., KIND, F., and GIARDINI, D. (2001), A theoretical investigation
of average H/V ratios. Geophys, J. Int., 145, 535–549.
FA¨ H D., KIND F., and GIARDINI D. (2003), Inversion of local S-wave
velocity structures from average H/V ratios, and their use for the
estimation of site-effects, Journ. Seismol. 7, 449–467.
GIULIVO, I., and SANTO, A. (1997), Stratigrafia del sottosuolo e
problemi geomorfologico-applicativi della citta` di Avellino,
‘‘Geologia delle grandi aree urbane’’—Progetto strategico CNR.
HERAK, M. (2008), ModelHVSR—a Matlab tool to model horizontal-
to-vertical spectral ratio of ambient noise, Computers
Geosci., 34, 1514–1526.
HORIKE, M., ZHAO, B., and KAWASE, H. (2001), Comparison of site
response characteristics inferred from microtremors and earthquake
shear waves, Bull. Seism. Soc. Am., 91, 1526–1536.
IBS-VON SEHT, M., and WOLHENBERG, J. (1999), Microtremor measurements
used to map thickness of soft sediments, Bull. Seism.
Soc. Am., 89, 250–259.
KO¨ HLER A., OHRNBERGER M., SCHERBAUM F., STANGE S., and KIND F.
(2004), Ambient vibration measurements in the southern Rhine
Graben close to Basle, Ann. Geophys., 47, 1771–1781.
KO¨ HLER, A., OHRNBERGER, M., and SCHERBAUM, F. (2006). The relative
fraction of Rayleigh and Love waves in ambient vibration
wave fields at different European sites, in 3rd Int. Symposium on
the Effects of Surface Geology on Seismic Motion, Grenoble,
France, Abstract 83.KONNO, K., and OHMACHI, T. (1998), Ground-motion characteristics
estimated from spectral ratio between horizontal and vertical
components of microtremors, Bull. Seism. Soc. Am., 88,
228–241.
KRAMER, S.L. (1996), Geotechnical Earthquake Engineering (Prentice
Hall, 1996).
LACHET, C., HATZFELD, D., BARD, P.Y., THEODULIDIS, N., PAPAIOANNOU,
C., and SAVVAIDIS, A. (1996), Site effects and microzonation
in the city of Thessaloniki (Greece). Comparison of different
approaches, Bull. Seism. Soc. Am., 86, 1692–1703.
LUZI, L., PUGLIA, R., PACOR, F., GALLIPOLI, M. R., BINDI, D., and
MUCCIARELLI, M. (2011), Proposal for a soil classification based
on parameters alternative or complementary to Vs,30. Bull
Earthquake Eng., doi:10.1007/s10518-011-9274-2.
MALISCHEWSKY P.G., and SCHERBAUM F. (2004), Love’s formula and
H/V-ratio (ellipticity) of Rayleigh waves, Wave Motion, 40,
57–67.
MARESCA R., GALLUZZO D., and DEL PEZZO, E. (2006), H/V spectral
ratios and array techniques applied to ambient noise recorded in
the Colfiorito Basin, central Italy, Bull. Seism. Soc. Am., 96,
490–505.
MELETTI, C., and MONTALDO, V. (2007), Stime di pericolosita` sismica
per diverse probabilita` di superamento in 50 anni: valori di
ag. Progetto DPC-INGV S1 (2006), Deliverable D2, http://
esse1.mi.ingv.it/d2.html.
MUCCIARELLI, M., and GALLIPOLI, M.R. (2006), Comparison
between Vs30 and other estimates of site amplification in Italy,
Conference on Earthquake Engineering and Seismology, Geneva,
3–8 Sept., no. 270.
NAKAMURA, Y. (1989), A method for dynamic characteristics estimation
of subsurface using microtremor on the ground surface,
Q. Rept. Railway Tech. Res. Inst., 30, 25–33.
NOGOSHI, M.,and IGARASHI, T. (1970), On the amplitude characteristics
of microtremors (Part 1), J. Seism. Soc. Japan, 23,
264–280.
NOGOSHI, M., and IGARASHI, T. (1971), On the amplitude characteristics
of microtremor (Part 2), J. Seism. Soc. Japan, 24, 26–40.
PAROLAI, S., BORMANN, P., and MILKREIT, C. (2002), New relationships
between Vs, thickness of sediments, and resonance
frequency calculated by the H/V ratio seismic noise for the
Cologne area (Germany), Bull. Seism. Soc. Am., 92, 2521–2527.
PILZ, M., PAROLAI, S., LEYTON, F., CAMPOS, J., and ZSCHAU, J. (2009),
A comparison of site response techniques using earthquake dataand ambient seismic noise analysis in the large urban areas of
Santiago de Chile, Geophys. J. Int., 178, 713–728.
PILZ, M., PAROLAI, S., PICOZZI,M., WANG, R., LEYTON, F., CAMPOS, J.,
and ZSCHAU, J. (2010), Shear wave velocity model of the Santiago
de Chile basin derived from ambient noise measurements: a
comparison of proxies for seismic site conditions and amplification,
Geophys. J. Int., 182, 355–367.
RODRIGUEZ, V.H.S., and MIDORIKAWA, S. (2002), Applicability of the
H/V spectral ratio of microtremors in assessing site effects on
seismic motion, Earthq. Eng. Struct. Dynamics, 31, 261–279.
SCHERBAUM F, HINZEN, K.G, and OHRNBERGER, M. (2003), Determination
of shallow shear wave velocity profiles in the Cologne/
Germany area using ambient vibrations, Geophys. J. Int. 152,
597–612.
SESAME (2004), Guidelines for the Implementation of the H/V
Spectral Ratio Technique on Ambient Vibrations. Measurements,
Processing and Interpretation. SESAME European Research
Project WP12—D23.12. http://sesame-fp5.obs.ujf-grenoble.fr/
Papers/HV_User_Guidelines.pdf.
SOURIAU, A., ROULLE´ , A., and PONSOLLES, C. (2007), Site effects in
the city of Lourdes, France, from H/V measurements: implications
for seismic-risk evaluation, Bull. Seism. Soc. Am., 97,
2118–2136.
TOKIMATSU, K., and MIYADERA, Y. (1992), Characteristics of Rayleigh
waves in microtremors and their relation to underground
structures, J. Struct. Constr. Eng. AIJ 439, 81–87 (in Japanese,
English abstract).
WATHELET, M., JONGMANS, D., OHRNBERGER, M., and BONNEFOYCLAUDET,
S. (2008), Array performances for ambient vibrations
on a shallow structure and consequences over Vs inversion, J.
Seismol., 12, 1–19.
WEBER, E., CONVERTITO, V., IANNACCONE, G., ZOLLO, A., BOBBIO, A.,
CANTORE, L., CORCIULO, M., DI CROSTA, M., ELIA, L., MARTINO,
C., ROMEO, A., and SATRIANO, C. (2007), An advanced seismic
network in the southern Apennines (Italy) for seismicity investigations
and experimentation with earthquake early warning,
Seism. Res. Lett., 78, 622–634.
WILLS, C.J., PETERSEN, M., BRYANT, W.A., REICHE, M., SAUCEDO,
G.J., TAN, S., TAYLOR, G., and TREIMAN, J. (2000), A site-conditions
map for California based in geology and shear-wave
velocity, Bull. Seism. Soc. Am., 90, S187–S208.