ArticlePublisher preview available

Geological and geotechnical investigation of the seismic ground response characteristics in some urban and suburban sites in Chile exposed to large seismic threats

August 2022
Bulletin of Earthquake Engineering 20(3)

August 2022
20(3)

DOI:10.1007/s10518-022-01401-3

Authors:

Jose Maringue

Pontificia Universidad Católica de Chile

Esteban Sáez

Pontificia Universidad Católica de Chile

Gonzalo Yanez

Pontificia Universidad Católica de Chile

Show all 13 authorsHide

The central area of Chile’s Valparaiso Region has been classified as a seismic gap for a major earthquake, which makes it very important to understand the seismic hazard of the zone. Generally, seismic codes consider a qualitative classification of sites to estimate the possible damage in the case of an earthquake scenario. Estimating the values of acceleration could be very important to prevent damages and increase preparedness for these rare events. In this research, a qualitative and quantitative estimation of seismic hazard is performed in the study area (Valparaiso region between Papudo and San Antonio 32°–34° S). This is achieved through an integrated and relatively economical approach which considers the information from Geology, Geophysical experiments (Gravity and seismic methods), and Geotechnical analyses. The results of the geophysical survey and geology information allow dividing the zone into five site types through a new proposal of site classification that depends not only on the Vs30, but also on the sites predominant period (T0), which is an innovation of this work for the Chilean code. The Peak Ground Acceleration (PGA) values in the study zone were estimated using a Ground Motion Predictive Equation developed for the Chilean subduction zone. Additionally, we consider three different seismic scenarios according to the history of events in Central Chile. The results of this quantitative analysis show PGA values up to 0.52 g for the median and 1.2 g for the 84th percentile of the scenarios. Overall, the highest accelerations (PGA) are in zones with low shear wave velocities (< 500 m/s), a long predominant period (> 0.4 s) and where geology establishes the presence of low stiffness soils. The comparison of response spectra from the model against records from 2010 Maule and 1985 Valparaiso earthquakes shows available models tend to overpredict the intensities.

Integrated approach diagram used in this investigation

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Large earthquakes of central Chile. Solid bars represent the estimated rupture length and the grey shaded area represents the seismic gap in the region ( Modified from Bravo et al. 2019 and references in). White rectangles represent the three seismic asperities near the study zone used in this work. Here, these asperities are named as I, II and III

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a Location of Geophysical test in the study area. b Geological map with the detailed location of geophysical test in Valparaíso and Viña del Mar. c Vs profile and H/V curve for red circle in panel (b). d Vs profile and H/V curve for green circle in panel (b)

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Example of the integrated analysis of a site. a Summary of the dispersion curves with different analysis for a single seismic measurement. The right portion of the figure corresponds to the active f-k analysis, while the left portion corresponds to SPAC analysis. The red curve is the result of the passive linear array. b Adjustment of the dispersion curve between observed (black curve) and the model from the inversion (colorful curve). c Vs-depth profile from the 1-D inversion. d HVSR analysis

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Digital elevation model (DEM, https://www.aw3d.jp/en/products/standard/) for a The whole study area and b the Valparaiso-Viña zone

…

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Vol.:(0123456789)

Bulletin of Earthquake Engineering (2022) 20:4895–4918

https://doi.org/10.1007/s10518-022-01401-3

1 3

ORIGINAL ARTICLE

Geological andgeotechnical investigation oftheseismic

ground response characteristics insome urban andsuburban

sites inChile exposed tolarge seismic threats

JoseMaringue1· LauraMendoza1,2· EstebanSáez1,2 · GonzaloYañez1·

GonzaloMontalva3,4· ValeriaSoto1,2· FelipeAyala1,2· NicolasPerez‑Estay1·

RonnyFigueroa1· NataliaSepúlveda5· CarlosGálvez5· PaolaRamírez5·

CarlosOvalle1,6

Received: 6 July 2021 / Accepted: 3 April 2022 / Published online: 16 May 2022

Abstract

The central area of Chile’s Valparaiso Region has been classiﬁed as a seismic gap for a

major earthquake, which makes it very important to understand the seismic hazard of the

zone. Generally, seismic codes consider a qualitative classiﬁcation of sites to estimate the

possible damage in the case of an earthquake scenario. Estimating the values of accelera-

tion could be very important to prevent damages and increase preparedness for these rare

events. In this research, a qualitative and quantitative estimation of seismic hazard is per-

formed in the study area (Valparaiso region between Papudo and San Antonio 32°–34° S).

This is achieved through an integrated and relatively economical approach which considers

the information from Geology, Geophysical experiments (Gravity and seismic methods),

and Geotechnical analyses. The results of the geophysical survey and geology information

allow dividing the zone into ﬁve site types through a new proposal of site classiﬁcation that

depends not only on the Vs30, but also on the sites predominant period (T0), which is an

innovation of this work for the Chilean code. The Peak Ground Acceleration (PGA) values

in the study zone were estimated using a Ground Motion Predictive Equation developed for

the Chilean subduction zone. Additionally, we consider three diﬀerent seismic scenarios

according to the history of events in Central Chile. The results of this quantitative analysis

show PGA values up to 0.52g for the median and 1.2g for the 84th percentile of the sce-

narios. Overall, the highest accelerations (PGA) are in zones with low shear wave veloci-

ties (< 500m/s), a long predominant period (> 0.4 s) and where geology establishes the

presence of low stiﬀness soils. The comparison of response spectra from the model against

records from 2010 Maule and 1985 Valparaiso earthquakes shows available models tend to

overpredict the intensities.

Keywords Seismic methods· Site ampliﬁcation attenuation models· Seismic

microzoning· Seismic hazard

* Esteban Sáez

esaez@ing.puc.cl

Extended author information available on the last page of the article

Content courtesy of Springer Nature, terms of use apply. Rights reserved.

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