Microtremors as a Geophysical Exploration Tool: Applications and Limitations

Delgado, José; Casado, Carlos López; Giner, J. J.; Estévez, Antonio; Cuenca, A.; Molina, Sergio

doi:10.1007/pl00001128

Cited by 145 publications

(86 citation statements)

References 7 publications

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“…Each H/V spectral ratio line corresponds to a discrete hour with a 5 min measurement. measurements were performed, as has also been observed by other researchers (DUVAL et al 1995;SUZUKI et al 1995;BOUR et al 1998;DELGADO et al 2000;LEBRUN et al 2001). …”

Section: Seasonal Variation Of the H/v Spectral Ratio Of Ambient Noisementioning

confidence: 51%

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: Seasonal Variation Of the H/v Spectral Ratio Of Ambient Noisementioning

confidence: 51%

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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“…Since the 1990s, several authors have introduced the H / V method as suitable for exploration studies (e.g. Ibs-von Seht and Wohlenberg, 1999;Delgado et al, 2000;Benjumea et al, 2011). These studies benefit from the relationship between the soil resonance frequency (υ 0 ) and bedrock depth (H ) to delineate bedrock geometry on basins (Gabàs et al, 2014).…”

Section: H / V Techniquementioning

confidence: 99%

Characterization of a complex near-surface structure using well logging and passive seismic measurements

Benjumea¹,

Macau²,

Gabàs³

et al. 2016

Solid Earth

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Abstract. We combine geophysical well logging and passive seismic measurements to characterize the near-surface geology of an area located in Hontomin, Burgos (Spain). This area has some near-surface challenges for a geophysical study. The irregular topography is characterized by limestone outcrops and unconsolidated sediments areas. Additionally, the near-surface geology includes an upper layer of pure limestones overlying marly limestones and marls (Upper Cretaceous). These materials lie on top of Low Cretaceous siliciclastic sediments (sandstones, clays, gravels). In any case, a layer with reduced velocity is expected. The geophysical data sets used in this study include sonic and gamma-ray logs at two boreholes and passive seismic measurements: three arrays and 224 seismic stations for applying the horizontal-to-vertical amplitude spectra ratio method (H/V). Well-logging data define two significant changes in the P -wave-velocity log within the Upper Cretaceous layer and one more at the Upper to Lower Cretaceous contact. This technique has also been used for refining the geological interpretation. The passive seismic measurements provide a map of sediment thickness with a maximum of around 40 m and shear-wave velocity profiles from the array technique. A comparison between seismic velocity coming from well logging and array measurements defines the resolution limits of the passive seismic techniques and helps it to be interpreted. This study shows how these low-cost techniques can provide useful information about near-surface complexity that could be used for designing a geophysical field survey or for seismic processing steps such as statics or imaging.

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“…The H/V method has been used for microzonation studies to predict site response to earthquake seismicity (e.g. Nakamura, 1989;Konno and Ohmachi, 1998;Rial et al, 1992) and as a method to estimate unconsolidated sediment thickness, map the bedrock surface, and infer fault locations (e.g., Ibs-von Seht and Wohlenberg, 1999;Delgado et al, 2000;Parolai et al, 2002). The resonance frequency, f rn , of the n mode is related to sediment thickness Z can be determined from the relation:…”

Section: Ambient Noise For Determination Of Site Dynamic Properties Amentioning

confidence: 99%

Ambient noise for determination of site dynamic properties at Hurghada and Safaga cities, Red Sea, Egypt

Toni¹

2016

Acta Geodynamica Et Geomaterialia

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Recording ambient noise at the surface is increasingly used for the assessment of site response and has become a fundamental task for seismic risk reduction in urbanized areas. Methods based on the measurement of seismic noise, which typically are fast, non invasive, and low cost, have become a very attractive option in microzonation studies. In the current work, we use the ambient noise recordings collected by single seismic stations and two-dimensional arrays to determine the response of the near-surface soil at the two touristic cities of Hurghada and Safaga which are located at the Red Sea coast in Egypt. Based on the horizontal-to-vertical (H/V) spectral ratio Nakamura's technique, recordings of the single stations are analyzed to estimate the fundamental site frequency (f 0 ). Using the raw noise signals recorded by two arrays, we present a joint inversion scheme for surface wave dispersion curves. In particular, the Rayleigh wave dispersion curves and the H/V curves are combined in a joint inversion procedure. We present inversion procedure based on the computation of high-frequency correlation functions between arrays' stations. The calculation of Rayleigh wave phase velocities is based on the frequency-domain SPatial AutoCorrelation (SPAC) and frequency-wavenumber (f-k) methods. Constitutively, a tomographic inversion of the travel-times estimated for each frequency is performed, allowing the vertically varying 1-D shear wave velocity structure below the array to be retrieved. Following the relationship between resonance frequency (f 0 ) and thickness of sediments, the thickness of unconsolidated sediments at the investigated sites are determined. ARTICLE INFO

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Microtremors as a Geophysical Exploration Tool: Applications and Limitations

Cited by 145 publications

References 7 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)

Characterization of a complex near-surface structure using well logging and passive seismic measurements

Ambient noise for determination of site dynamic properties at Hurghada and Safaga cities, Red Sea, Egypt

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