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| Titel |
Seismic local site effects characterization in the Andarax River Valley (SE Spain) from ambient seismic noise |
| VerfasserIn |
Enrique Carmona, Antonio García-Jerez, Francisco Luzón, Francisco Sánchez-Martos, Francisco J. Sánchez-Sesma, José Piña |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250097766
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| Publikation (Nr.) |
 EGU/EGU2014-13375.pdf |
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| Zusammenfassung |
| This work is focused on the characterization of seismic local effects in the Low Andarax
River Valley (SE Spain). The Low Andarax River valley is located in an active
seismic region, with the higher seismic hazard values in Spain. The landform is
composed mainly by sedimentary materials which increase its seismic hazard due to
the amplification of the seismic inputs and spectral resonances. We study seismic
local effects in the Low Andarax River by analyzing the Horizontal-to-Vertical
Spectral Ratio (HVSR) of ambient noise records. The noise data were recorded
during two field campaigns in 2012 and 2013. There have been a total of 374 noise
measurements with 15 and 30 minutes duration. The acquisition was performed
with a Digital Broadband Seismometer Guralp CMG-6TD. The distance between
measurements was about 200 meters, covering an area around 40 km2. There have been
6 significant peak frequencies between 0.3 Hz and 5 Hz. It was possible to find
interesting areas with similar spectral peaks that coincide with zones with similar
microgravimetric anomalies at the alluvial valley. It is also observed a decrease
in the frequency peaks from West to East suggesting increased sediment layer.
We also compute the soil models at those sites where geotechnical information
is available, assuming that the seismic noise is diffuse. We invert the HVSR for
these places using horizontally layered models and in the imaginary part the Green
functions at the source. It is observed that the S wave velocity inverted models are
consistent with the known geotechnical information obtained from drilled boreholes. We
identify the elastodynamic properties of the limestone-dolomite materials with a
formation of phyllites and quartzite that form the basement of the depression, and those
properties of the Miocene and Pliocene detrital deposits (marls, sandy silts, sands
and conglomerates) that fill the valley. These results together with the observed
resonant frequencies along the Andarax valley allow the construction of microzonation
maps, which are very useful for public administrations and private geotechnical
companies.
ACKNOWLEDGEMENTS. This research has been partially supported by the MINECO
research project CGL2010-16250, Spain, by the EU with FEDER, by DGAPA-UNAM under
Project IN104712, and the AXA Research Fund. |
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