Publication Date:
2021-06-22
Description:
In this work, we analyse continuous measurements of microseisms to assess the reliability of
the fundamental resonance frequency estimated by means of the horizontal-to-vertical (H/V)
spectral ratio within the 0.1–1 Hz frequency range, using short-period sensors (natural period
of 1 s). We apply the H/V technique to recordings of stations installed in two alluvial basins
with different sedimentary cover thicknesses—the Lower Rhine Embayment (Germany) and
the Gubbio Plain (Central Italy). The spectral ratios are estimated over the time–frequency
domain, and we discuss the reliability of the results considering both the variability of the
microseism activity and the amplitude of the instrumental noise. We show that microseisms
measured by short period sensors allow the retrieval of fundamental resonance frequencies
greater than about 0.1–0.2 Hz, with this lower frequency bound depending on the relative
amplitude of themicroseism signal and the self-noise of the instruments. In particular,we show
an examplewhere the considered short-period sensor is connected to instruments characterized
by an instrumental noise level which allows detecting only fundamental frequencies greater
than about 0.4 Hz. Since the frequency at which the peak of the H/V spectral ratio is biased
depends upon the seismic signal-to-instrument noise ratio, the power spectral amplitude of
instrumental self-noise should be always considered when interpreting the frequency of the
peak as the fundamental resonance frequency of the investigated site.
Description:
Published
Description:
175-184
Description:
4.1. Metodologie sismologiche per l'ingegneria sismica
Description:
JCR Journal
Description:
open
Keywords:
site effects
;
fourier analysis
;
04. Solid Earth::04.06. Seismology::04.06.01. Earthquake faults: properties and evolution
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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