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| Titel |
New developments in ambient noise analysis to characterise the seismic response of landslide-prone slopes |
| VerfasserIn |
V. Gaudio, J. Wasowski, S. Muscillo |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 13, no. 8 ; Nr. 13, no. 8 (2013-08-20), S.2075-2087 |
| Datensatznummer |
250085501
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| Publikation (Nr.) |
 copernicus.org/nhess-13-2075-2013.pdf |
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| Zusammenfassung |
| We report on new developments in the application of ambient noise analysis
applied to investigate the dynamic response of landslide-prone slopes to
seismic shaking, with special attention to the directional resonance
phenomena recognised in previous studies. These phenomena can be relevant
for seismic slope susceptibility, especially when maximum resonance
orientation is close to potential sliding directions. Therefore, the
implementation of an effective technique for site response directivity
detection is of general interest. In this regard methods based on the
calculation of horizontal-to-vertical noise spectral ratio (HVNR) are
promising. The applicability of such methods is investigated in the area of
Caramanico Terme (central Italy), where ongoing accelerometer monitoring of
slopes with different characteristics offers the possibility of validation
of HVNR analysis. The noise measurements, carried out in different times to
test the result repeatability, revealed that sites affected by response
directivity persistently show major peaks with a common orientation,
consistent with the resonance direction inferred from accelerometer data. In
some cases such a directivity turned out parallel to maximum slope
direction, but this cannot be considered a systematic feature of slope
dynamic response. At sites where directivity is absent, the HVNR peaks do
not generally show a preferential orientation, with rare exceptions that
could be linked to the presence of temporarily active sources of polarised
noise. The observed variations of spectral ratio amplitude can be related to
temporal changes in site conditions (e.g. groundwater level/soil water
content variations affecting P wave velocity and Poisson's ratio of
surficial layer), which can hinder the recognition of main resonance
frequencies. Therefore, we recommend conducting simultaneous measurements at
nearby sites within the same study area and repeating measurements at
different times in order to distinguish significant systematic polarisation
caused by site-specific response directivity from polarisation controlled by
properties of noise sources. Furthermore, an analysis of persistence in
noise recordings of signals with systematic directivity showed that only a
portion of recordings contains wave trains having a clear polarisation
representative of site directional resonance. Thus a careful selection of
signals for HVNR analysis is needed for a correct characterisation of site
directional properties. |
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