Site effect evaluation in the basin of Santiago de Chile using ambient noise measurements

Abstract

S U M M A R YWe performed extensive ambient vibration measurements in the basin of Santiago de Chile (Chile), and we look for testing the reliability of the horizontal-to-vertical amplitude spectra ratio method (H/V ) as a tool to provide qualitative and quantitative information of site effects in complex geological media. The interpretation of the H/V data was carried out conformably to the SESAME project consensus criteria and outlines three major patterns: (1) clear peaked H/V curves related to sharp underground velocity contrast; (2) H/V peak of low amplitude and flat curve related to weak contrast and (3) broad H/V peak indicating the presence of strong lateral variations of underground structure. H/V measurements, however, reveal a discrepancy between the computed soil resonance frequencies and the expected building resonance, therefore not leading to a straight interpretation of the intensity distribution derived from observed damage to one storey houses in Santiago after the 1985 Valparaiso earthquake. Indeed, the H/V technique mostly maps the first fundamental frequency; however, it fails to show higher resonance modes. In the case of the city of Santiago, this method works well for assessing the seismic hazard for high-rise buildings, but is questionable for smaller structures as is the case of a great percentage of constructions in the city.

Estimation of Subsurface Soil Layers using H/V Spectrum of Densely Measured Microtremor Observations (Case Study: Yogyakarta City, Central Java-Indonesia)

“…The final H/V ratio and the associated standard deviation are obtained by averaging the H/V ratios from all windows. The standard deviations on H/V ratio curves are estimated considering the arithmetic average for all individual logarithms of the H/V ratio computed for each time window [10].…”

Seismic site characterization of the Kastelli (Kissamos) Basin in northwest Crete (Greece): assessments using ambient noise recordings

“…The results allow us to infer that the amplitude quality criteria of A>2 proposed by Sesame might be too restricted since neighboring sites presenting stability in the HVSR shape and frequencies show HVSR peak slightly below and beyond 2.0. Suggestions that the amplitude clarity criteria of A >2 might be too restricted have been also mentioned by Bonnefoy-Claudet et al (2008) and Pilz et al (2009).…”

“…The HVSR method has been used for site effects assessment in various geomorphological cases and microzonation studies (e.g Chavez-Garcia et al 1995;Teves-Costa et al 1996;Bard 1998;Mucciarelli et al 2003a;Cara et al 2003;Bindi et al 2009;Beroya et al 2009;Gallipoli et al 2011;Strollo et al 2011;Puglia et al 2011;Mucciarelli 2011). HVSR has been also applied in several Basins indicating the contribution of the local geomorphology on seismic ground motion (e.g Teves-Costa et al 1996;Gueguen et al 2000;Lebrun et al 2001;Gosar 2007;Bonnefoy-Claudet et al 2008;Özalaybey et al 2011 ;). …”

Profundidad del basamento derivado de la gravedad en la Cuenca de Santiago: implicancias para la evolución geológica, hidrogeológica, geotermia de baja entalpiía, caracterización de suelos y peligros geológicos.

“…As a background, the natural crustal seismicity (CHASE and ANILLO projects, (Pardo et al, , 2009; and NEIC and DGF data bases), and the Geological map 1:1,000,000 (Sernageomin, 2002). Pasten, 2007;Bonnefoy-Claudet et al, 2009). A compilation based on these results, and unpublished data from F. Leyton, personal communication, 2014, is presented in figure 13 in terms of fundamental frequency (F o ) and maximum peak amplitude (A o ).…”