On the role of stiff soil deposits on seismic ground shaking in western Liguria, Italy: Evidences from past earthquakes and site response

2017 ◽  
Vol 226 ◽  
pp. 172-183 ◽  
Author(s):  
Roberto De Ferrari ◽  
Gabriele Ferretti ◽  
Simone Barani ◽  
Giacomo Pepe ◽  
Andrea Cevasco
Keyword(s):  
Site Response ◽  
Ground Shaking ◽  
Soil Deposits ◽  
Stiff Soil

The site response of two rock and soil station pairs to strong and weak ground motion

1991 ◽  
Vol 81 (5) ◽  
pp. 1885-1899
Author(s):  
Robert B. Darragh ◽  
Anthony F. Shakal
Keyword(s):  
Ground Motion ◽  
Site Response ◽  
Soft Soil ◽  
Ground Acceleration ◽  
Ground Shaking ◽  
Soil Site ◽  
Rock Site ◽  
Loma Prieta ◽  
Strong Ground ◽  
Stiff Soil

Abstract The site response to strong and weak ground motion depends largely on the subsurface conditions at the soil site for the two rock-soil station pairs studied. The first station pair consists of a soft-soil site (Treasure Island) and a sandstone and shale site (Yerba Buena Island). These stations recorded strong ground shaking from the Loma Prieta mainshock and weak ground motion from four aftershocks. The range of peak ground acceleration is from approximately 0.00006 to 0.07 g at the rock site. Compared to the rock site, the strong ground motion at the soft-soil site is amplified by a factor of about 3 over a frequency range from 0.5 to 2.0 Hz. The amplification is much higher for weak motion and suggests a dependence on signal amplitude. For example, near 1 Hz, the site response shows an increasing amplification as magnitude (and the peak velocity at the rock site) decreases. For events of local magnitude 7.0, 4.3, 4.1, 3.5, and 3.3, the maximum soil-site amplifications are 4, 12, 17, 19, and 25, respectively. A second station pair consisting of a stiff-soil site (Gilroy #2) and a sandstone site (Gilroy #1) was also studied with contrasting results. These two stations recorded strong ground shaking from the 1979 Coyote Lake, 1984 Morgan Hill, and 1989 Loma Prieta mainshocks. Weak ground motion was recorded at these stations after the Loma Prieta mainshock. The range of peak ground acceleration is from 0.006 to 0.43 g at the rock site. Unlike the results for the soft-soil study above, the estimated stiff-soil site responses are not significantly different for strong and weak motion from 0.5 to 2.0 Hz. Near 0.7 Hz, the stiff-soil site responses range from 2.5 to 4.5 for strong ground shaking from three mainshocks and from 1.5 to 4.0 for weak ground shaking from thirteen aftershocks.

Simplified Criteria to Select Ground Response Analysis Methods for Seismic Building Design: Equivalent Linear versus Nonlinear Approaches

2021 ◽  
Author(s):  
Mauro Aimar ◽  
Sebastiano Foti
Keyword(s):  
Seismic Waves ◽  
Site Response ◽  
Building Design ◽  
Soil Conditions ◽  
Response Analysis ◽  
Depth Range ◽  
Ground Response Analysis ◽  
Equivalent Linear ◽  
Acceleration Time Histories ◽  
Soil Deposits

ABSTRACT The possible amplification of seismic waves in soil deposits is crucial for the seismic design of buildings and geotechnical systems. The most common approaches for the numerical simulation of seismic site response are the equivalent linear (EQL) and the nonlinear (NL). Even though their advantages and limitations have been investigated in several studies, the relative field of applicability is still under debate. This study tested both methods over a wide population of soil models, which were subjected to a set of acceleration time histories recorded from strong earthquakes. A thorough comparison of the results of the EQL and the NL approaches was carried out, to identify the conditions in which the relative differences are significant. This assessment allowed for the definition of simplified criteria to predict when the two schemes are or are not compatible for large expected shaking levels. The proposed criteria are based on simple and intuitive parameters describing the soil deposit and the ground-motion parameters, which can be predicted straightforwardly. Therefore, this study provides a scheme for the choice between the EQL and the NL approaches that can be used even at the preliminary design stages. It appears that the EQL approach provides reliable amplification estimates in soil deposits with thickness up to 30 m, except for very deformable soils, but this depth range may be extended at long vibration periods. This result reveals a good level of reliability of the EQL approach for various soil conditions encountered in common applications, even for high-intensity shaking.

scholarly journals Government Administrative Control Tower in Crisis Management System: Definition, Issues, and Policy Implications

2015 ◽  
Vol 30 (3) ◽  
pp. 125-145
Author(s):  
Lee Dalgon
Keyword(s):  
Decision Making ◽  
Crisis Management ◽  
Management System ◽  
Prime Minister ◽  
Site Response ◽  
Management Control ◽  
Policy Implications ◽  
Administrative Control ◽  
Site Control

A number of scholars and media in South Korea have recently raised questions regarding the necessity of a "government administrative control tower" (GACT) for dealing with crises. This paper aims to conceptualize GACT as a crisis management system and suggests administrative methods for improving this model by examining issues raised by its operation. Since the control tower is critical in times of crisis, this paper limits its focus to the role of GACT as a crisis management control tower. In crisis, an on-site control tower focuses especially on prevention, and on-site response and management must be synchronized with a higher-level administrative decision making control tower for the system to operate properly. While a fully authorized on-site control tower should serve as the central agent, a higher-level administrative decision making control tower should mobilize additional organizations and resources to support on-site capability. The operating principle for the latter should be to create an environment in which heterogeneous parties work together to make decisions about what to do rather than the president or the prime minister directly making orders and taking control.

scholarly journals Basement Mapping of the Fucino Basin in Central Italy by ITRESC Modeling of Gravity Data

Geosciences ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 398
Author(s):  
Federico Cella ◽  
Rosa Nappi ◽  
Valeria Paoletti ◽  
Giovanni Florio
Keyword(s):  
Seismic Activity ◽  
Site Response ◽  
Gravity Data ◽  
A Priori ◽  
Central Italy ◽  
Gravity Anomalies ◽  
Gravity Modeling ◽  
Ground Shaking ◽  
Sedimentary Evolution ◽  
Fucino Basin

Sediments infilling in intermontane basins in areas with high seismic activity can strongly affect ground-shaking phenomena at the surface. Estimates of thickness and density distribution within these basin infills are crucial for ground motion amplification analysis, especially where demographic growth in human settlements has implied increasing seismic risk. We employed a 3D gravity modeling technique (ITerative RESCaling—ITRESC) to investigate the Fucino Basin (Apennines, central Italy), a half-graben basin in which intense seismic activity has recently occurred. For the first time in this region, a 3D model of the Meso-Cenozoic carbonate basement morphology was retrieved through the inversion of gravity data. Taking advantage of the ITRESC technique, (1) we were able to (1) perform an integration of geophysical and geological data constraints and (2) determine a density contrast function through a data-driven process. Thus, we avoided assuming a priori information. Finally, we provided a model that honored the gravity anomalies field by integrating many different kinds of depth constraints. Our results confirmed evidence from previous studies concerning the overall shape of the basin; however, we also highlighted several local discrepancies, such as: (a) the position of several fault lines, (b) the position of the main depocenter, and (c) the isopach map. We also pointed out the existence of a new, unknown fault, and of new features concerning known faults. All of these elements provided useful contributions to the study of the tectono-sedimentary evolution of the basin, as well as key information for assessing the local site-response effects, in terms of seismic hazards.

scholarly journals The Role of Seismological Networks in Civil Protection in Low and High Seismic Hazards

2021 ◽  
Author(s):  
Erzsébet Győri ◽  
Arman Bulatovich Kussainov ◽  
Gyöngyvér Szanyi ◽  
Zoltán Gráczer ◽  
Kendebay Zhanabilovich Raimbekov ◽  
...  
Keyword(s):  
Early Warning ◽  
Early Warning Systems ◽  
Economic Losses ◽  
Civil Protection ◽  
Warning Systems ◽  
Ground Shaking ◽  
Research Areas ◽  
Seismic Networks ◽  
Strong Ground

Earthquakes are one of the most devastating natural disasters on Earth, causing sometimes huge economic losses and many human casualties. Since earthquake prediction is not yet possible, the purpose of civil protection is to reduce damage and protect human lives, in which the seismological networks of different countries play a very important role. Special applications of seismic networks are the early warning systems that can be used to protect vulnerable infrastructures using automated shutdown procedures, to stop high velocity trains and to save lives if the general public is notified about imminent strong ground shaking. In this paper, we describe the aims and operation of seismological networks, covering in more detail the early warning systems. Then we delineate the seismotectonic settings and seismicity in Hungary and Kazakhstan, furthermore, describe the operating seismological networks and the related scientific research areas with emphasis on civil protection. Hungary and Kazakhstan differ not only in the size of their territory, but also in their seismicity, therefore, in addition to the similarities, there are also significant differences between the aims and problems of their seismological networks.

Comparison of Invasive and Non-Invasive Methods in Site Response, Case Study: Soil Deposits of La Estrella

2021 ◽  
Vol 906 (1) ◽  
pp. 012119
Author(s):  
Daniel Largo ◽  
César Hidalgo ◽  
Juan Olarte
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Spectrum Analysis ◽  
Site Response ◽  
Response Spectrum ◽  
Response Spectrum Analysis ◽  
Non Invasive ◽  
Soil Deposits ◽  
Relative Differences

Abstract A great part of the Colombian territory is under medium to high seismic hazard due to the complex tectonic condition, which in turn affects, particularly, areas where the population density is highest. A response spectrum analysis of the ground is currently required by seismic design codes for site response analysis. For this, the shear wave velocity (Vs) profile must be established. The use of seismic invasive methods such as Down Hole or Cross Hole for the determination of the shear wave velocity (Vs), has been typically recommended. In recent years, significant progress has been made in non-invasive seismic methods such as MasW (Multichannel Analysis of Surface Waves) and ReMi (Refraction Microtremor), in order to estimate the Vs profile from surface waves analysis. Due to the accessibility and low cost, these methods represent a viable alternative to determine the profile of Vs. In this project, the seismic response of soil deposits was evaluated in the La Estrella municipality located in the south of The Aburrá Valley. One-dimensional (1D) models were simulated by characterizing the soil profile through the shear wave velocity with MasW and ReMi seismic tests. The results were compared with models based on shear wave characterization through Down Hole methods. The 1D response spectrums were determined with an equivalent linear model in DEEPSOIL and GTS NX software. The resulting spectra were compared through relative difference and correlation coefficient. Final results demonstrated that the spectra present low relative differences for long periods, moderate relative differences for moderate periods, and low to moderate relative differences for short periods. The general correlation coefficients were 0.6. This was evidence that non-invasive seismic methods allow an appropriate response spectrum analysis.

Evaluation of stratigraphic effects on seismic site response over large areas: the case study of Italy

2021 ◽  
Author(s):  
Gaetano Falcone ◽  
Gianluca Acunzo ◽  
Amerigo Mendicelli ◽  
Federico Mori ◽  
Giuseppe Naso ◽  
...  
Keyword(s):  
Ground Motion ◽  
Site Effects ◽  
Risk Mitigation ◽  
Site Response ◽  
Free Field ◽  
Response Spectra ◽  
Seismic Intensity ◽  
Site Condition ◽  
Ground Shaking ◽  
Seismic Site Response

<p>Estimation of site effects over large areas is a key-issue for land management and emergency system planning in a risk mitigation perspective. In general, site-conditions are retrieved from available global datasets and the ground-shaking estimation is based on ground motion prediction equations.</p><p>An advanced procedure to estimate site effects over large areas is here proposed with reference to the Italian territory. Site-condition were defined for homogenous morpho-geological areas in accordance to the borehole logs and the geophysical data archived in the Italian database for seismic microzonation (https://www.webms.it/). Ground motion modifications were determined by means of about 30 milion of one-dimensional numerical simulations of local seismic site response. Correlations between amplification factors (i.e. the ratio between free-field and outcrop response spectra), AF, and site-condition (i.e. harmonic mean of the shear wave velocity in the upper 30 m of the deposit, V<sub>S30</sub>) were determined for each morpho-geological homogeneous area depending on the reference seismic intensity (i.e. referred to the outcropping stiff rock characterised by V<sub>S30</sub> ≥ 800 m/s). The AF-V<sub>S30</sub> correlations were proved to satisfactory forecast the site effects when compared with the results of site specific estimation of local seismic site response.</p>

Evaluation of the seismic response at the Arquata Del Tronto hamlet through 3D numerical analyses

2020 ◽  
Author(s):  
Ilaria Primofiore ◽  
Julie Marie-Pierre Baron ◽  
Giovanna Laurenzano ◽  
Peter Klin ◽  
Cristina Muraro ◽  
...  
Keyword(s):  
Seismic Response ◽  
Earthquake Engineering ◽  
Site Response ◽  
Central Italy ◽  
Seismic Microzonation ◽  
Numerical Analyses ◽  
Topographic Effects ◽  
Ground Response ◽  
Relevant Role

<p><sub>([email protected]; </sub><sub>[email protected]; [email protected]; [email protected]; </sub><sub>[email protected]; [email protected])</sub></p><p> </p><p>The 2016 Italian seismic sequence showed, once again, the relevant role of the differentiated seismic effects at short distance in varied geological environments. In the case study of Arquata del Tronto hamlet, several response analyses have been performed in order to reproduce the ground response through 2D finite element numerical codes (Primofiore, 2019; Pagliaroli et al., 2019). According to the Italian Guidelines for Seismic microzonation ICMS (2010), in the case of hills, the topographic effects of seismic amplification must be studied by numerical methods. In those cases, when the relieves are made up of soil deposits, 2D numerical analyses are used, indeed. Instead, when rocky hills are considered, the amplification effects due to the topography are considered by means of 1D simplified analyses or at most, 2D ground response analyses. The recent damages of old settlements located on the top of rocky hills, such as Arquata del Tronto hill, put in evidence the relevant role of three-dimensional movements of asymmetrical isolated rocky reliefs in generating heavy disruptions during the seismic shaking. In addition, on surface there are commonly fracturing layers of rocks, which played an important role in amplifying seismic waves according to their thicknesses. 3D numerical analyses at Arquata del Tronto hill have been carried out through the spectral element method implemented in SPECFEM3D code. Results suggested that an accurate simulation of the topographic effects of isolated asymmetrical rocky hills can be appreciated only through 3D numerical analyses, because they capture the out-of-plane bending moment (torsional effect) that asymmetry induces. The results showed that seismic behaviour of articulated morphology of the isolated relieves cannot be simulated by means of 2D seismic response analyses.</p><p> </p><p><sub>References</sub></p><p> </p><p><sub>Pagliaroli, A., Pergalani, F., Ciancimino, A., et al. (2019). Site response analyses for complex geological and morphological conditions: relevant case-histories from 3rd level seismic microzonation in Central Italy. </sub></p><p><sub>Bulletin of Earthquake Engineering, 1-37.</sub></p><p> </p><p><sub>Primofiore, I. (2019). Studio della risposta sismica in località Arquata del Tronto mediante modellazioni numeriche 3D. Master Degree thesis (in Italian), University “G. d’ Annunzio” of Chieti-Pescara.</sub></p><p> </p><p><sub>Working group M. S. (2010). ICMS - Indirizzi e Criteri per la Microzonazione Sismica. In Conferenza delle Regioni e delle Provincie autonome. Dipartimento della protezione civile, Roma (Vol. 3).</sub></p><p> </p>

Sign in / Sign up

Export Citation Format

Share Document