Surface Soil Effects Study Using Short-period Microtremor Observations in Almería City, Southern Spain

Navarro, Manuel; Enomoto, Takahisa; Sánchez, Francisco Javier Alejandre; Matsuda, Iware; Iwatate, Takahiro; Posadas, A. M.; Luzón, Francisco; Vidal, F.; Seo, Kazuoh

doi:10.1007/978-3-0348-8177-7_12

Cited by 11 publications

(18 citation statements)

References 15 publications

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“…At all sites, variation in amplitude level of the noise H/V spectral ratio is present. Such a variation also has been observed by other researchers (e.g., TEVES-COSTA et al 1996;NAVARRO et al 2001;ALFARO et al 2001). Furthermore, for the majority of the sites the amplitude level of the fundamental frequency during the morning time period is smaller than for the night-time period.…”

Section: Diurnal Variation Of the H/v Spectral Ratio Of Ambient Noisesupporting

confidence: 62%

Reliability of Ambient Noise Horizontal-to-Vertical Spectral Ratio in Urban Environments: The Case of Thessaloniki City (Northern Greece)

Panou

Theodulidis

Hatzidimitriou

et al. 2005

Pure appl. geophys.

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In the framework of an ambient noise measurement project in the downtown district of the City of Thessaloniki (Northern Greece), several tests and evaluation of noise recordings were performed in selected sites. This data set was processed and compared with previous results for the same sites in terms of horizontal-to-vertical (H/V) spectral ratio obtained from weak and strong motion earthquake data. The recording system used was tested against a reference one. Finally, systematic ambient noise measurements were performed at eight sites in the city's downtown area, to evaluate diurnal and seasonal variations. It was concluded that the recording system used was reliable and the ambient noise H/V spectral ratios were in good agreement with relevant results previously obtained. Diurnal variation of the ambient noise H/V spectral ratio showed that it is preferable to perform measurements during the calm hours of the day, when man-made noise is relatively low. However, no systematic seasonal fluctuation effect on the ambient noise H/V spectral ratio was identified.

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Section: Diurnal Variation Of the H/v Spectral Ratio Of Ambient Noisesupporting

confidence: 62%

Reliability of Ambient Noise Horizontal-to-Vertical Spectral Ratio in Urban Environments: The Case of Thessaloniki City (Northern Greece)

Panou

Theodulidis

Hatzidimitriou

et al. 2005

Pure appl. geophys.

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“…Several studies show the relationship between the velocity structure beneath the recording site and the dominant frequency obtained from HVSR analysis (see for example NAVARRO et al, 2001). As a first-order approximation, we can apply a simple formula that relates the fundamental frequency to the thickness and seismic velocity of a medium composed of a single layer over a half-space:…”

Section: Discussionmentioning

confidence: 99%

Microtremor Analyses at Teide Volcano (Canary Islands, Spain): Assessment of Natural Frequencies of Vibration Using Time-dependent Horizontal-to-vertical Spectral Ratios

Almendros

Luzón

Posadas

2004

Pure and Applied Geophysics

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We use time-dependent horizontal-to-vertical spectral ratios (HVSR) of microtremors to determine the dominant frequencies of vibration of the geological structures beneath several recording sites in the vicinity of Teide volcano (Canary Islands, Spain). In the microtremors, the time-dependent HVSRs (ratiograms) are a useful tool to discriminate between the presence of real dominant frequencies linked to resonances of the subsurface structure and the spurious appearance of peaks due to local transients. We verified that the results are repeatable, in the sense that microtremors recorded at the same site but at different times yield a very similar HVSR function. Two types of results are found: (1) sites where there is no resonance of the propagating microtremors, and therefore no value of a dominant frequency can be assessed; and (2) sites where a stationary peak in the HVSR is found and a dominant frequency related to resonance of the shallow structure can be estimated. These resonant frequencies show substantial spatial variations even for nearby sites, which reflects the complexity of the shallow velocity structure in the Las Can˜adas area. Large dominant frequencies occur near the caldera walls and also at a few locations that coincide with the intersections of the inferred rims of the three calderas forming Las Can˜adas. Small dominant frequencies also occur near the caldera rim, and may be due to discontinuities in the caldera wall and/or to local velocity anomalies. Intermediate frequencies are mostly found in the eastern part of the caldera, where a tentative profile of the basement depth has been obtained. Intermediate frequencies have also been measured south of Ucanca and south of Montan˜a Blanca. In view of the present results, we conclude that the use of ratiograms constitutes an improvement of the HVSR method and provides an appropriate tool to investigate the shallow velocity structure of a volcanic region.

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“…A new grouping of soils in 32 classes was made later mainly through geological (lithology, genesis and age) and seismic-geotechnical criteria (hardness/compactness, shear wave velocity, tectonization, saturation, neotectonics and thickness) as well as considering the results of recent research conducted in Andalusian urban areas (e.g. Navarro et al 2001Navarro et al , 2007Alcalá-García et al 2002;Al Yuncha et al 2004;García-Jerez et al 2006). Then, those groups were classified considering their dynamic behaviour according to the average shear-wave velocity in the upper 30 m of soil, V 30 S .…”

Section: Geotechnical Classification and Amplification Factorsmentioning

confidence: 99%

A new seismic hazard assessment in the region of Andalusia (Southern Spain)

Benito

Navarro

Vidal

et al. 2010

Bull Earthquake Eng

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A probabilistic seismic hazard assessment of Andalusia (Southern Spain) in terms of peak ground acceleration, PGA, and spectral accelerations, SA(T), is presented in this paper. In contrast to most of the previous studies in the region, which were performed for PGA, making use of Intensity-to-PGA relationships, hazard was here calculated in terms of magnitude, using published spectral ground-motion models. Moreover, we considered different ground-motion models for the Atlantic sources, since the attenuation of those motions seems to be slower, as evidenced in the case of the extensive macroseismic areas of earthquakes like those occurred in the years 1755, 1969 and 2007. A comprehensive review of the seismic catalogue and of the seismogenic models proposed for the region was carried out, including those for Northern Africa, which is part of the influence area. Hazard calculations were performed following the Probabilistic Seismic Hazard Assessment (PSHA) methodology using a logic tree, which accounts for six different seismic source zonings and five different ground-motion attenuation relationships. Hazard maps in terms of PGA and SA (0.2 s) and SA (1 s) and coefficient of variation (COV) maps, for the 475-year return period were first obtained in rock sites. A geotechnical classification and amplification factors were proposed and new hazard maps including local effects were represented, showing PGA values ranging from 24 to 370 cm/s 2 for the whole Andalusian territory, with the highest expected values (PGA > 300 cm/s 2 ) in some parts of the Granada Province and in the town of Vélez Málaga. Lowest values (PGA < 50 cm/s 2 ) correspond to some towns of the Huelva 123 740 Bull Earthquake Eng (2010) 8: and Córdoba provinces. The inclusion of soil effects provides a more detailed picture of the actual hazard the region is subjected to.

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Surface Soil Effects Study Using Short-period Microtremor Observations in Almería City, Southern Spain

Cited by 11 publications

References 15 publications

Reliability of Ambient Noise Horizontal-to-Vertical Spectral Ratio in Urban Environments: The Case of Thessaloniki City (Northern Greece)

Reliability of Ambient Noise Horizontal-to-Vertical Spectral Ratio in Urban Environments: The Case of Thessaloniki City (Northern Greece)

Microtremor Analyses at Teide Volcano (Canary Islands, Spain): Assessment of Natural Frequencies of Vibration Using Time-dependent Horizontal-to-vertical Spectral Ratios

A new seismic hazard assessment in the region of Andalusia (Southern Spain)

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