Physical stratigraphy and geotechnical properties controlling the local seismic response in explosive volcanic settings: the Stracciacappa maar (central Italy)

AbstractNowadays, policies addressed to prevention and mitigation of seismic risk need a consolidated methodology finalised to the assessment of local seismic response in explosive volcanic settings. The quantitative reconstruction of the subsoil model provides a key instrument to understand how the geometry and the internal architecture of outcropping and buried geological units have influence on the propagation of seismic waves. On this regard, we present a multidisciplinary approach in the test area of the Stracciacappa maar (Sabatini Volcanic District, central Italy), with the aim to reconstruct its physical stratigraphy and to discuss how subsoil heterogeneities control the 1D and 2D local seismic response in such a volcanic setting. We first introduce a new multidisciplinary dataset, including geological (fieldwork and log from a 45-m-thick continuous coring borehole), geophysical (electrical resistivity tomographies, single station noise measurements, and 2D passive seismic arrays), and geotechnical (simple shear tests performed on undisturbed samples) approaches. Then, we reconstruct the subsoil model for the Stracciacappa maar in terms of vertical setting and distribution of its mechanical lithotypes, which we investigate for 1D and 2D finite element site response analyses through the application of two different seismic scenarios: a volcanic event and a tectonic event. The numerical modelling documents a significant ground motion amplification (in the 1–1.5 Hz range) revealed for both seismic scenarios, with a maximum within the centre of the maar. The ground motion amplification is related to both 1D and 2D phenomena including lithological heterogeneity within the upper part of the maar section and interaction of direct S-waves with Rayleigh waves generated at edges of the most superficial lithotypes. Finally, we use these insights to associate the expected distribution of ground motion amplification with the physical stratigraphy of an explosive volcanic setting, with insights for seismic microzonation studies and local seismic response assessment in populated environments.

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Ground-motion amplification at the Colle di Roio ridge, central Italy: a combined effect of stratigraphy and topography

Geophysical Journal International ◽

10.1093/gji/ggw120 ◽

2016 ◽

Vol 206 (1) ◽

pp. 1-18 ◽

Cited By ~ 20

Author(s):

S. Hailemikael ◽

L. Lenti ◽

S. Martino ◽

A. Paciello ◽

D. Rossi ◽

...

Keyword(s):

Ground Motion ◽

Central Italy ◽

Combined Effect ◽

Ground Motion Amplification

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Are Synthetic Accelerograms Suitable for Local Seismic Response Analyses at Near-Field Sites?

Bulletin of the Seismological Society of America ◽

10.1785/0120210074 ◽

2021 ◽

Author(s):

Francesca Mancini ◽

Sebastiano D’Amico ◽

Giovanna Vessia

Keyword(s):

Seismic Response ◽

Seismic Waves ◽

Near Field ◽

Central Italy ◽

Propagation Path ◽

Soil Behavior ◽

Seismic Stations ◽

Seismic Input ◽

Local Seismic Response ◽

Finite Fault

ABSTRACT Local seismic response (LSR) studies are considerably conditioned by the seismic input features due to the nonlinear soil behavior under dynamic loading and the subsurface site conditions (e.g., mechanical properties of soils and rocks and geological setting). The selection of the most suitable seismic input is a key point in LSR. Unfortunately, few recordings data are available at seismic stations in near-field areas. Then, synthetic accelerograms can be helpful in LSR analysis in urbanized near-field territories. Synthetic accelerograms are generated by simulation procedures that consider adequately supported hypotheses about the source mechanism at the seismotectonic region and the wave propagation path toward the surface. Hereafter, mainshocks recorded accelerograms at near-field seismic stations during the 2016–2017 Central Italy seismic sequence have been compared with synthetic accelerograms calculated by an extended finite-fault ground-motion simulation algorithm code. The outcomes show that synthetic seismograms can reproduce the high-frequency content of seismic waves at near-field areas. Then, in urbanized near-field areas, synthetic accelerograms can be fruitfully used in microzonation studies.

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Reconstruction of a Reference Subsoil Model for the Seismic Microzonation of Gori (Georgia): A Procedure Based on Principal Component Analysis (PCA)

Bulletin of the Seismological Society of America ◽

10.1785/0120200341 ◽

2021 ◽

Author(s):

Silvia Giallini ◽

Enrico Paolucci ◽

Pietro Sirianni ◽

Dario Albarello ◽

Iolanda Gaudiosi ◽

...

Keyword(s):

Principal Component Analysis ◽

Seismic Response ◽

Principal Component ◽

Component Analysis ◽

Vibration Monitoring ◽

Ambient Vibration ◽

Geological Evidence ◽

Local Seismic Response ◽

Geophysical Surveys ◽

Single Station

ABSTRACT This article focuses on the full exploitation of geological and economically viable geophysical surveys for the seismic characterization of the shallow subsoil in the frame of microzonation studies in urban areas where economic resources for detailed seismic response analyses are scarce. In these conditions, the outcomes of inexpensive geophysical surveys (e.g., based on ambient vibration monitoring or surface-wave prospecting) must be fully exploited. To reduce the uncertainties related to these kinds of procedures, their joint interpretation in the light of geological evidence is mandatory. To this purpose, we propose the application of principal component analysis to combine the results of distributed single-station ambient vibration measurements (horizontal-to-vertical spectral ratio [HVSR] technique) to provide a preliminary zonation of the study area. The zones identified in this way are then characterized by considering the available geognostic boreholes, VS profiles deduced by the joint inversion of HVSR curves, and available Rayleigh-wave dispersion curves deduced from active seismic prospecting (multichannel analysis of surface-waves technique). The final outcome allows the definition of a preliminary seismic model of the study area, which is also constrained by the available geological data deduced from on-purpose surveys. The proposed approach has been applied to the city of Gori (Georgia). The proposed approach allowed a reliable assessment of buried geometries, geological domains, and the distribution of lithofacies, which can control the local seismic response. In detail, the major role of paleovalley infills and interfluve domains has been enlightened by adding in evidence concerning the peculiar stratigraphic relationships and buried morphologies, which may determine 1D and 2D resonance effects.

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Seismic characterization of Pizzoli (Central Italy) to estimate site effects induced by near-fault earthquakes

10.5194/egusphere-egu21-3169 ◽

2021 ◽

Author(s):

Marco Tallini ◽

Paola Monaco ◽

Marco Spadi ◽

Anna Chiaradonna ◽

Felicia Papasodaro

Keyword(s):

Ground Motion ◽

Active Fault ◽

Central Italy ◽

Soil Liquefaction ◽

Core Drilling ◽

Near Fault ◽

Near Fault Earthquakes ◽

Subsoil Model ◽

Near Fault Ground Motion

Most of the towns, villages and infrastructures settled in Central Italy are placed nearby active faults and, consequently, the ground motion evaluation and the ground failures characterization under near-fault earthquakes are noteworthy issues to be investigated. The Madonna delle Fornaci - MDF &#8211; site, close to Pizzoli village (L&#8217;Aquila in Central Italy), has been selected as an emblematic site for assessing the effects induced by near-fault earthquakes, because it is located very close to the Pizzoli-Barete active Fault accountable for the February 2, 1703 Mw 6.67 earthquake. After this historical earthquake, remarkable surface manifestations, attributed to soil liquefaction and coseismic ground sinkholes, were observed at the MDF site, occurred in the Holocene alluvial deposit of the Aterno River, as witnessed by several written sources (among which Uria De Llanos, 1703). As concerns the geological setting, the MDF site is placed in the Plio-Quaternary NW-SE elongated L&#8217;Aquila intramontane basins which is bounded by a framework of active NW-SE trending and SW-dipping extensional faults which includes also the above mentioned Pizzoli-Barete active Fault. A comprehensive geophysical, geological, and geotechnical campaign has been carried out at the MDF site with the goal to obtain the seismic site characterization and the shallow and deep subsoil model preparatory to the quantitative estimation of the near-fault ground motion and the evaluation of the soil liquefaction potential induced by the 1703 seismic event.The field survey consisted of three shallow continuous core drilling 15-20 m-deep boreholes; in one of the them, a down hole test and SPT measurements were conducted every 1 m depth; an open tube piezometer at the 11-12 m depth was installed in one of the boreholes; a couple of undisturbed samples were sampled for geotechnical laboratory tests; a MASW, Seismic refraction and ERT investigations were performed along two perpendicular 70-m long alignments; several single station microtremor measurements performed also in the neighbouring area. These data permitted preliminary to elaborate a quite confident 1-2D litho- and seismo-stratigraphic model for the MDF test site.The MDF site is characterized by mainly calcareous grain-supported Holocene alluvial deposit: sandy gravel and gravelly sand with a silty component, sometimes predominant, in the matrix with water table level about 8-12 m b.g.l. Moreover, the following horizons are noteworthy to mention: an orange sand level at 11-12 m b.g.l. which could be considered preliminary as a liquefaction-prone level and an organic reddish-brown silty clay at 14-15 m b.g.l., which could be used for C14 dating.Further, a 200 m-deep continuous core drilling borehole, executed nearby the MDF site by ISPRA for the mapping of the Italian geological sheet 348 &#8220;Antrodoco&#8221;, was also taken into consideration to obtain the complete 1D subsoil model for the near-fault ground motion amplification modelling.The near-fault ground motion evaluation of the MDF site, considered as paradigmatic of the Central Italy seismicity, will go on through the geotechnical characterization of the alluvial deposits, the shear wave velocity versus depth profile and the seismic input evaluation to use for the numerical modelling.

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Local Seismic Response in a Large Intra-mountain Basin as Observed from Earthquakes and Microtremor Recordings: The Avezzano Area (Central Italy)

Engineering Geology for Society and Territory - Volume 5 ◽

10.1007/978-3-319-09048-1_220 ◽

2014 ◽

pp. 1153-1157 ◽

Cited By ~ 1

Author(s):

Daniela Famiani ◽

Paolo Boncio ◽

Fabrizio Cara ◽

Rocco Cogliano ◽

Giuseppe Di Giulio ◽

...

Keyword(s):

Seismic Response ◽

Central Italy ◽

Local Seismic Response

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Developing effective subsoil reference model for seismic microzonation studies.

10.21203/rs.3.rs-804952/v1 ◽

2021 ◽

Author(s):

Pierluigi Pieruccini ◽

Enrico Paolucci ◽

Pier Lorenzo Fantozzi ◽

Duccio Monaci Naldini ◽

Dario Albarello

Keyword(s):

Ground Motion ◽

Reference Model ◽

Low Cost ◽

Methodological Approach ◽

Central Italy ◽

Seismic Microzonation ◽

Ground Motion Amplification ◽

Geophysical Model ◽

Geophysical Information ◽

Model C

Abstract A general methodological approach is here discussed to integrate geological and geophysical information in seismic microzonation studies. In particular, the methodology aims at maximizing the exploitation of low-cost data for extensive preliminary assessment of ground motion amplification phenomena induced by the local seismostratigraphical configuration. Three main steps are delineated: a) the combination of geological/geomorphological analyses to develop an Engineering-Geological Model of the study area; b) targeted geophysical prospecting to provide an Engineering-Geological/Geophysical Model; c) evaluating effectiveness of Engineering-Geological/Geophysical Model by estimating expected ground motion amplification phenomena by the use of suitable computational tools. The workflow is illustrated by a case-study based on a set of villages in the Umbro-Marchean Apennine (Central Italy) damaged during the Seismic sequence occurred in Central Italy during 2016–2017.

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Investigation of topographic site effects using 3D waveform modelling: amplification, polarization and torsional motions in the case study of Arquata del Tronto (Italy)

Bulletin of Earthquake Engineering ◽

10.1007/s10518-021-01270-2 ◽

2021 ◽

Author(s):

Julie Baron ◽

Ilaria Primofiore ◽

Peter Klin ◽

Giovanna Vessia ◽

Giovanna Laurenzano

Keyword(s):

Numerical Simulations ◽

Seismic Response ◽

Ground Motion ◽

Frequency Band ◽

Site Response ◽

Central Italy ◽

Surface Model ◽

Torsional Motion ◽

Near Surface

AbstractThe combined effect of topography and near-surface heterogeneities on the seismic response is hardly predictable and may lead to an aggravation of the ground motion. We apply physics-based numerical simulations of 3D seismic wave propagation to highlight these effects in the case study of Arquata del Tronto, a municipality in the Apennines that includes a historical village on a hill and a hamlet on the flat terrain of an alluvial basin. The two hamlets suffered different damage during the 2016 seismic sequence in Central Italy. We analyze the linear visco-elastic seismic response for vertically incident plane waves in terms of spectral amplification, polarization and induced torsional motion within the frequency band 1–8 Hz over a 1 km2 square area, with spatial resolution 25 m. To discern the effects of topography from those of the sub-surface structure we iterate the numerical simulations for three different versions of the sub-surface model: one homogeneous, one with a surficial weathering layer and a soil basin and one with a complex internal setting. The numerical results confirm the correlation between topographic curvature and amplification and support a correlation between the induced torsional motion and the topographic slope. On the other hand we find that polarization does not necessarily imply ground motion amplification. In the frequency band above 4 Hz the topography-related effects are mainly aggravated by the presence of the weathering layer, even though they do not exceed the soil-related effects in the flat-topography basin. The geological setting below the weathering layer plays a recognizable role in the topography-related site response only for frequencies below 4 Hz.

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Investigation of Topographic Site Effects using 3D Waveform Modelling: Amplification, Polarization and Torsional Motions in the Case Study of Arquata del Tronto (Italy)

10.21203/rs.3.rs-582452/v1 ◽

2021 ◽

Author(s):

Julie Baron ◽

Ilaria Primofiore ◽

Peter Klin ◽

Giovanna Laurenzano ◽

Giovanna Vessia

Keyword(s):

Numerical Simulations ◽

Seismic Response ◽

Ground Motion ◽

Frequency Band ◽

Structural Model ◽

Site Response ◽

Central Italy ◽

Torsional Motion ◽

Near Surface

Abstract The combined effect of topography and near-surface heterogeneities on the seismic response is hardly predictable and may lead to an aggravation of the ground motion. We apply physics-based numerical simulations of 3D seismic wave propagation to highlight these effects in the case study of Arquata del Tronto, a hamlet in the Apennines that suffered irregularly distributed damage during the 2016 seismic sequence in Central Italy. We analyze the linear visco-elastic seismic response for vertically incident plane waves in terms of spectral amplification, polarization and induced torsional motion within the frequency band 1–8 Hz over a 1 km2 square area, with spatial resolution 25 m. To discern the effects of topography from those of the sub-surface structure we iterate the numerical simulations for three different versions of the structural model: one homogeneous, one with a surficial weathering layer and a soil basin and one with a complex internal structure. The numerical results confirm the correlation between topographic curvature and amplification and support a correlation between the induced torsional motion and the topographic slope. On the other hand we find that polarization does not necessarily imply ground motion amplification. In the frequency band above 4 Hz the topography-related effects are mainly aggravated by the presence of the weathering layer, even though they do not exceed the soil-related effects in the flat-topography basin. The structure below the weathering layer plays a recognizable role in the topography-related site response only for frequencies below 4 Hz.

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