Seismic Site Effects Research Articles

Correction: Kim, H.; et al. Geospatial Assessment of the Post-Earthquake Hazard of the 2017 Pohang Earthquake Considering Seismic Site Effects. ISPRS Int. J. Geo-Inf. 2018, 7, 375

We have recently been made aware of errata and omissions in the introduction section for describing the seismological characteristics of the 2017 Pohang earthquake as stated in the title of this article, which was recently published in ISPRS [...]

Site-Specific Zonation of Seismic Site Effects by Optimization of the Expert GIS-Based Geotechnical Information System for Western Coastal Urban Areas in South Korea

Earthquake-induced disasters are often more severe over soft soils than over firm soils or rocks owing to the seismic site effects related to the amplification of ground motion. On a regional scale, such differences can be estimated by spatially predicting the subsurface soil thickness over the entire target area. Generally, soil deposits are deeper in coastal or riverside areas than in inland regions. In this study, the seismic site effects in the coastal metropolitan areas of Incheon and Bucheon, South Korea, were assessed to provide information on seismic hazards. Spatial prediction of geotechnical layers was performed for the entire study area within an advanced GIS framework. Approximately 7500 existing borehole records in the Incheon and Bucheon areas were gathered and archived into a GIS database. Surface geotechnical data were acquired from a walk-over survey. Based on the optimized geo-data, spatial zoning maps of site-specific seismic response parameters, based on multiscale geospatial modeling, were created and presented for use in a regional seismic mitigation strategy. Seismic zonation was also performed to determine site coefficients for seismic design over the entire target area and to compare them with each other. We verified that the geotechnical data based spatial zonation would be useful for seismic hazard mitigation.

Geospatial Assessment of the Post-Earthquake Hazard of the 2017 Pohang Earthquake Considering Seismic Site Effects

The 2017 Pohang earthquake (moment magnitude scale: 5.4) was South Korea’s second strongest earthquake in decades, and caused the maximum amount of damage in terms of infrastructure and human injuries. As the epicenters were located in regions with Quaternary sediments, which involve distributions of thick fill and alluvial geo-layers, the induced damages were more severe owing to seismic amplification and liquefaction. Thus, to identify the influence of site-specific seismic effects, a post-earthquake survey framework for rapid earthquake damage estimation, correlated with seismic site effects, was proposed and applied in the region of the Pohang earthquake epicenter. Seismic zones were determined on the basis of ground motion by classifying sites using the multivariate site classification system. Low-rise structures with slight and moderate earthquake damage were noted to be concentrated in softer sites owing to the low focal depth of the site, topographical effects, and high frequency range of the mainshocks.

Derive empirical fragility functions for Nepali residential buildings

Fragility functions are the key components of damage analysis for the next generation performance-based earthquake engineering (PBEE-2) framework. Despite being widely discussed and researched topic in almost all seismically active regions, fragility functions for Nepali buildings are not widely researched to date. This paper derives empirical fragility functions for residential buildings using more than a million damage data from the 1934 Bihar-Nepal earthquake (MW ∼8.4), 1980 Chainpur earthquake (MW 6.5), 1988 Eastern Nepal earthquake (MW 6.8), 2011 Eastern Nepal earthquake (MW 6.9), and 2015 Gorkha seismic sequence (MW 7.8). A new damage classification system is proposed in this study and fragility functions for reinforced concrete, brick masonry, and stone masonry building classes are derived. As seismic site effects is one of the leading factor contributing damage in the case of Himalayan earthquakes, fragility functions considering seismic site effects are also derived for all three building classes. Finally, fragility functions derived in this study are compared with existing fragility functions and discussion regarding the discrepancies is presented. Together with the fragility functions, building taxonomy and vulnerability of all existing buildings in Nepal are outlined in this paper.

Empirical seismic site effect analysis for the city of Tehran using H / V and methods

This paper presents empirical seismic site effect analysis for Tehran city, the capital of Iran. Empirical methods using both spectral ratio of the horizontal components of sedimentary site to rocky site (/) (site/reference) and horizontal to vertical spectral ratio (H / V) are considered. To estimate the seismic site effect parameters using the empirical methods, recorded motions from Firozabad-Kojour (2004) and Kahak-Qom (2007) earthquakes are analysed. The recorded motions in rocky stations are used for the / method. Site amplification ratios in various frequency ranges are extracted from the results of both / and H / V methods. The peak surface accelerations are computed using the site amplification ratios, for different frequency ranges, and compared with the recorded peak accelerations. Based on the values of the least square relative errors, the results from the method for the 1–10 Hz frequency range show a good agreement between the calculated and recorded peak surface accelerations, and thus, this frequency range can be considered a reliable range for the results of this study to be used for seismic design purposes in the study area.

Correlation between earthquake damage and seismic site effects: The study case of Lentini and Carlentini, Italy

On December 13th 1990 a magnitude 5.6 seismic event, felt throughout Sicily, and having maximum seismic intensity VII-VIII, occurred. Although, it is classified as moderate magnitude, it caused causalities and the collapse of a few buildings. Two of the most struck cities were Carlentini and Lentini, located in south-eastern Sicily at about 20 km from the instrumental epicenter. In order to evaluate the influence of ground features on the damage distribution, both vulnerability and damage maps were drawn using information collected in about 6000 forms coming from official ascertainments. Significant damage observed in some portions of the investigated areas, appears related to the modest quality of the buildings that were classified as medium to high vulnerability. To evaluate the role played by the geologic setting, two sites were instrumented to measure shear-wave velocity of the main lithotypes. Sixty-three ambient vibrations measurements were also performed both in free field and inside some buildings. Moreover, using information coming from geological and geophysical surveys, 1D numerical modelling were done to achieve information about the main ground motion parameters. The results highlight the occurrence of significant site effects and the potential presence of resonance phenomena between site and structure during the occurrence of a seismic event. Seismic site amplifications together with the buildings' vulnerability, observed through damage surveys, contributed to enhance the inherent seismic risk of the investigated area.

Geo-Proxy-Based Site Classification for Regional Zonation of Seismic Site Effects in South Korea

Seismic site effects and topographic effects related to ground motion occur during an earthquake due to site-specific geotechnical or geological characteristics, including the geological or geographical structure and the characteristics of near-surface sub-soil layers. Site-specific site effects due to geological conditions have been confirmed in recent earthquake events. Earthquake-induced damage has mainly occurred at accumulated soft soil layers under basins or along coasts and rivers. An alternative method has recently been proposed for evaluating regional seismic site effects and amplification factors using digital elevation models (DEM). High-quality DEMs at high resolutions may be employed to resolve finer-scale variations in topographic gradients and consequently, correlated site response parameters. Because there are many regions in South Korea lacking borehole datasets, which are insufficient for site classification only using borehole datasets, a DEM-based proxy for seismic zonation can be effective. Thus, in this study, geo-proxy-based site classification was proposed based on empirical correlations with site response parameters and conducted for regional zonation of seismic site effects to identify the amplification of characteristics in the western metropolitan areas of South Korea, depending on the site-specific geo-spatial conditions.

Analysis of nonlinear soil-structure interaction effects: 3D frame structure and 1-Directional propagation of a 3-Component seismic wave

In this paper, a finite element modeling technique, taking into account the effects of soil-structure interaction (SSI) is proposed for structural analysis and design. The one-dimensional model of a nonlinear multilayered soil profile is assembled with a multi-story multi-span frame model and the dynamic equilibrium problem is solved directly. The one-directional propagation of three-component seismic waves (1D-3C) is modeled taking into account the SSI, in the case of rigid shallow foundation and negligible rocking effects.The 1D-3C wave propagation model provides the three components of motion at the base of the frame structure, allowing the reduction of mesh size and computation time, compared with a fully three-dimensional model, and avoiding modeling difficulties to realize a reliable three-dimensional soil domain, related among others to boundary conditions.The proposed model allows the analysis of those structural dynamic features, seismic wave and local soil stratigraphy, that produce changes in the ground motion at the surface. The model reproduces well expected phenomena, in the case of layered soil with increasing nonlinearity and for different inertia distribution in the frame structure. SSI combined with seismic site effects is analyzed in a Japanese soil profile, using as seismic loading a 3C record of 2011 Tohoku earthquake.

Soil classification for seismic site effect using MASW and ReMi methods: A case study from western Anatolia (Dikili -İzmir)

The study area is located in the northern part of Izmir, Western Turkey, prone to an active tectonic extensional regime and includes typical features of sedimentary basins, horst-grabens surrounded by a series of normal and strike-slip faults. In September 1939 the Dikili (Kabakum) earthquake with a magnitude of Mw: 6.6 occurred and after this phenomenon, residents moved from the west of Dikili to the east (i.d. soft sediments to relative to rock area). A proper estimate of the earthquake-related hazard for the area is the main objective of this study. The site effect and soil engineering problems for estimating hazard parameters at the soil surface need to be carefully analyzed for seismic site classification and geo-engineering problems like soil liquefaction, soil settlement, soil bearing capacity and soil amplification. To solve the soil static and dynamic problems, shear-wave velocities have been used in a joint interpretation process; Multichannel Analysis of Surface Waves (MASW) and Refraction Microtremor (ReMi) analyses were conducted on 121 sites with 300×300 m grid size in an area of 60km2. It has been proposed that the probability of an earthquake with a magnitude of Mw: 6 occurring within 10years is 64%, when considering the Gutenberg-Richter model. This puts the region under an important earthquake risk. The estimated Vs30 values are ≤180m/s in the central and the northernmost part of the study area are showing an E type soil after the classification of NEHRP, where alluvial deposits are dominant. Vs30 values in the north and central part are between 180≤Vs≤360m/s suggesting a D type soil. In the southernmost part of the study area where volcanic rocks are widely distributed, Vs30 values range between 360 and 908m/s, corresponding to a C type and B type soil. The results show that soil liquefaction induced settlement and soil amplification are the most important problems in the south and the northernmost part of the study area, which is densely populated and encompasses the urbanized part of the study region.

Regional Assessment of Seismic Site Effects and Induced Vulnerable Area in Gyeonggi-do, South Korea, Using GIS

Regional Assessment of Seismic Site Effects and Induced Vulnerable Area in Gyeonggi-do, South Korea, Using GIS

Application of microtremor HVSR method for preliminary assessment of seismic site effect in Ngipik landfill, Gresik

This paper presents an investigation based on affected areas of earthquakes based on the micro-tremor horizontal-to-vertical ratio (HVSR) method around the Ngipik Landfill, Gresik. Ngipik landfill applies an Open dumping system with no protective layer to prevent groundwater pollution. Hence, the effect of the earthquake was investigated for preliminary assessment of leachate’s leakage. The micro-tremor measurements were performed by dividing the area into a grid with a 25m distance. The predominant frequency (f0) ranges between 1.1 and 3.65 Hz and the peak of HVSR (Am) varies from 2.04 to 7.16. The vulnerability index (kg) displayed the level of soil damage due to ground motions; the highest kg values signified the weaker zones during earthquakes and also indicated the leachate spread. The result of this paper might consider to seismic stability analysis of leachate recirculation landfill.

Introducing a New Method for Ground Structure Estimation using Microtremor Array Observation Technique

Ground structure characteristic is an important parameter in seismic site effect evaluation for earthquake structural design. Many geophysical methods can be used to estimate ground structure. The best field measurement option that requires least field effort and yet producing accurate estimation is the main concern of this study. This study applies microtremor array observation method to investigate the accuracy of dispersion curve estimated using Centerless Circular Array (CCA) methods of 5m radius. The dispersion curve observed was assessed by comparing to theoretical dispersion curve generated from proposed shear wave velocity (VS) profile of sites. The observed dispersion curve shows good agreement with theoretical dispersion curve over a wide frequency range, which is ranging from 3 - 10 Hz. This segment of dispersion curve can be utilized to estimate ground structure by means of inversion of dispersion curve. CCA method is capable to be used to estimate ground structure in term of VS profile.

Seismic site effect analysis for the city of Tehran using equivalent linear ground response analysis

Equivalent linear ground response analysis is conducted to evaluate seismic site effects in Tehran, Iran. Recorded bedrock motions in acceleration stations within Tehran are scaled based on the peak bedrock acceleration distribution map for a 475-year return period. The seismic responses of sites categorised as class C, based on Building Seismic Safety Council classification system, are obtained using the equivalent linear ground response analysis and available geotechnical and geophysical data. The results of site response analysis are presented in terms of site response spectra and amplification factors, computed in period ranges of 0.1–0.5 s and 0.1–2.5 s. The estimated site response spectra are compared with the suggested spectra in the Iranian Code (Standard No. 2800) and International Building Code (IBC 2015). While the comparison reveals an acceptable agreement between the estimated response spectra and IBC 2015, a significant discrepancy is observed with respect to the Iranian Code.

Local site effect of a clay site in Shiraz based on seismic hazard of Shiraz Plain

Propagation of seismic waves through soil layers would drastically change the frequency content and amplitude-based features of ground motions at the surface. These alterations are known as seismic site effects. Computation of site effects of high-populated areas such as large cities is of great importance (e.g., it is used in development of seismic microzonation of a region). Shiraz is one of the most populous cities of Iran and is located in a high seismic hazardous region. A representative clay site in this city is selected to assess local site effects. The time series and random vibration theory procedure in the frequency domain are implemented to analyze the aforementioned site. Furthermore, the nonlinear dynamic soil behavior is simulated by the equivalent linear method and the nonlinear method via DEEPSOIL program. Three types of soil column uncertainties such as shear wave velocity, modulus reduction, and damping ratio of soil layers as well as depth of underlying rock half-space (D bed) are considered herein. The mean amplification and standard deviation of natural logarithm of amplification factors are computed for a variety of analysis types. The results of the current study show that the computed mean and standard deviation of amplification factor in ln units by considering only V S uncertainty are in good agreement with the corresponding ones by considering V S and modulus reduction and damping ratio variabilities simultaneously for the studied site. Furthermore, it seems that the effect of bedrock depth in definition of spectral shapes of the Iranian seismic building code should be taken into account.

Numerical Modeling of Seismic Site Effects in a Shallow Alluvial Basin of the Northern Apennines (Italy)

Research Article| September 25, 2017 Numerical Modeling of Seismic Site Effects in a Shallow Alluvial Basin of the Northern Apennines (Italy) Claudia Madiai; Claudia Madiai aDipartimento di Ingegneria Civile e Ambientale, Università degli Studi di Firenze, via Santa Marta 3, 50139 Florence, Italy, claudia.madiai@unifi.it Search for other works by this author on: GSW Google Scholar Johann Facciorusso; Johann Facciorusso aDipartimento di Ingegneria Civile e Ambientale, Università degli Studi di Firenze, via Santa Marta 3, 50139 Florence, Italy, claudia.madiai@unifi.it Search for other works by this author on: GSW Google Scholar Elisa Gargini Elisa Gargini aDipartimento di Ingegneria Civile e Ambientale, Università degli Studi di Firenze, via Santa Marta 3, 50139 Florence, Italy, claudia.madiai@unifi.it Search for other works by this author on: GSW Google Scholar Author and Article Information Claudia Madiai aDipartimento di Ingegneria Civile e Ambientale, Università degli Studi di Firenze, via Santa Marta 3, 50139 Florence, Italy, claudia.madiai@unifi.it Johann Facciorusso aDipartimento di Ingegneria Civile e Ambientale, Università degli Studi di Firenze, via Santa Marta 3, 50139 Florence, Italy, claudia.madiai@unifi.it Elisa Gargini aDipartimento di Ingegneria Civile e Ambientale, Università degli Studi di Firenze, via Santa Marta 3, 50139 Florence, Italy, claudia.madiai@unifi.it Publisher: Seismological Society of America First Online: 27 Sep 2017 Online Issn: 1943-3573 Print Issn: 0037-1106 Bulletin of the Seismological Society of America (2017) 107 (5): 2094–2105. https://doi.org/10.1785/0120160293 Article history First Online: 27 Sep 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Claudia Madiai, Johann Facciorusso, Elisa Gargini; Numerical Modeling of Seismic Site Effects in a Shallow Alluvial Basin of the Northern Apennines (Italy). Bulletin of the Seismological Society of America 2017;; 107 (5): 2094–2105. doi: https://doi.org/10.1785/0120160293 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyBulletin of the Seismological Society of America Search Advanced Search Abstract The main purpose of this work is to investigate the basin‐edge effects on a cross section of an alluvial basin in the northern Apennines (Italy) and to compare the results with those obtained by applying existing approximate criteria to account for valley effects in cases of simple geometrical and stratigraphic conditions. The combined influence of geometry and layering of the basin was evaluated by performing 1D and 2D numerical analyses. The examined site is located in one of the highest seismicity zones of Tuscany. Geological, geophysical, and geotechnical information is obtained from extensive surveys carried out in the area as part of a pioneering Italian project (1998–2004) promoted and supported by the Regional Government of Tuscany to address microzoning studies on an urban scale. Five actual accelerometric signals were adopted in the analyses, consistent with a site reference spectrum defined according to Italian building code. To estimate the additional valley effects on the ground surface of the basin, numerical results from a 2D model were compared with the corresponding 1D numerical results obtained for an isolated soil column at the same location. A large number of vertical soil profiles were analyzed along the cross section, and different types of amplification factors were computed with reference to both peak ground accelerations and elastic response spectra. The results obtained were compared with those of existing approximate approaches for estimating basin effects on basic geometric and geological conditions (sine‐ or trapezoidal‐shaped valley, homogeneous soil deposits), fitting the actual cross section by a simplified symmetrical trapezoidal scheme. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Spatial distribution of soil shear-wave velocity and the fundamental period of vibration – a case study of the Saguenay region, Canada

ABSTRACTThe spatial distribution of soil shear-wave velocity and the fundamental period of vibration were selected as input parameters for the determination of potential seismic site effects in the Saguenay region, Canada. The methodology used in this study involved three clear steps. First, a 3D geological model of the surficial deposits was built taking into consideration the type, spatial distribution and thickness of the deposits. Second, representative average Vs values were determined for each of the major soil units. Finally, the average shear-wave velocity from the ground surface to bedrock (Vsav), the shear-wave velocity of the upper 30 m (Vs30) and the fundamental site resonance period (T0) were calculated over a regular grid for the study area. The results include the spatial distribution of the fundamental site resonance period, the average shear-wave velocity in the first 30 m of the ground and the spatial distribution of National Building Code of Canada seismic soil classes for the Saguenay region.

Toward an integrated seismic risk assessment for nuclear safety improving current French methodologies through the SINAPS@ research project

The Tohoku earthquake and associated tsunami in March 2011 caused a severe nuclear accident at the Fukushima Daiichi Nuclear Power Plant, where level 7 (International Atomic Energy Agency (IAEA) – INES scale) meltdown at three reactors occurred. The underestimation of the seismic and tsunami hazards has been recognized and the seismic margins assessment of the nuclear plants remains a priority for the whole nuclear community. In this framework a five-year research project called SINAPS@ (Earthquake and Nuclear Installations: Ensuring and Sustaining Safety) is currently on-going in France. A reliable estimate of seismic margins is possible only if all uncertainties, epistemic and aleatory, are effectively identified, quantified and integrated in the seismic risk analysis. SINAPS@ brings together a multidisciplinary community of researchers and engineers from the academic and the nuclear world. SINAPS@ aims at exploring the uncertainties associated to databases, physical processes and methods used at each stage of seismic hazard, site effects, soil and structure interaction, structural and nuclear components vulnerability assessments, in a safety approach: the main objective is ultimately to identify the sources of potential seismic margins resulting from assumptions or when selecting the seismic design level or the design strategy. The whole project is built around an “integrating” work package enabling to test state-of-the-art practices and to challenge new methodologies for seismic risk assessment: the real case of Kashiwazaki-Kariwa Japanese nuclear plant, shocked by the severe earthquake in 2007 provided a rich dataset which will be used to compare with the predictions. The present paper proposes for each step of the seismic risk analysis a review of the state of practice in France in the nuclear field and then precise the objectives and research strategy of SINAPS@ to overcome identified limitations or weaknesses. Scientific issues are illustrated through preliminary results of the project.

GIS-based regional assessment of seismic site effects considering the spatial uncertainty of site-specific geotechnical characteristics in coastal and inland urban areas

ABSTRACTEarthquake-induced hazards are profoundly affected by site effects related to the amplification of ground motions, which are strongly influenced by site-specific geologic conditions such as soil thickness, bedrock depth and soil stiffness. Seismic disasters are often more severe in coastal or riverside locations than over stiff soils or rocks due to differences in local site effects. In this study, a recently developed geographic information system-based framework was applied in coastal and inland urban areas in Korea, and its applicability for regional assessments was evaluated using appropriate geostatistical zonation of site-specific seismic site effects. The proposed framework was composed of four functional components: multivariable statistical clustering, geostatistical optimization, geotechnical analysis, and local visualization. The framework was applied in the Seoul and Busan areas of Korea for consideration of site effects in inland and coastal urban areas. Such zones of thick soil, or with a deep depth to bedrock, are susceptible to ground motion amplification due to site effects during earthquakes. The earthquake losses associated with possible building damage can be estimated based on spatial zoning maps considering geological and topographical characteristics and by a comparison of the spatial correlations of seismic site classes between inland and coastal areas of Korea.

Analysis of the Seismic Site Effects along the Ancient Via Laurentina (Rome)

This paper presents an evaluation of the Local Seismic Response (LSR) along the route of the ancient Roman road Via Laurentina , which has been exposed in several areas of southwest Rome over the last decade during the construction of new buildings and infrastructures. It is an example of LSR analysis applied to ancient and archaeological sites located in alluvial valleys with some methodological inferences for the design of infrastructure and urban planning. Since the ancient road does not cross the alluvial valley (namely the Fosso di Vallerano Valley) normal to its sides, it was not possible to directly perform 2D numerical modelling to evaluate the LSR along the road route. Therefore, outputs of 2D numerical models obtained along three cross sections that were normal oriented respect to the valley were projected along the route of the Via Laurentina within a reliable buffer attributed according to an available high-resolution geological model of the local subsoil. The modelled amplification functions consider physical effects due to both the 2D shape of the valley and the heterogeneities of the alluvial deposits. The 1D and 2D amplification functions were compared to output that non-negligible effects are related to the narrow shape of the fluvial valley and the lateral contacts between the lithotecnical units composing the alluvial fill. The here experienced methodology is suitable for applications to the numerical modelling of seismic response in case of linear infrastructures (i.e., roads, bridges, railways) that do not cross the natural system along physically characteristic directions (i.e. longitudinally or transversally).

Geospatial Big Data-Based Geostatistical Zonation of Seismic Site Effects in Seoul Metropolitan Area

Seismic site effects are influenced mainly by geospatial uncertainties corresponding to geological or geotechnical spatial variance. Therefore, the development of a geospatial database is essential to characterize site-specific geotechnical information in multiscale areas and to optimize geospatial zonation methods with potentially high degrees of spatial variability based on trial-and-error geostatistical assessments. In this study, a multi-source geospatial information framework, which included the construction of a big data platform, estimation of geostatistical density, optimization of the geostatistical interpolation method, assessment of seismic site effects, and determination of geospatial zonation for decision making, was established. Then, this framework was applied to the Seoul metropolitan area, South Korea. The GIS-based framework was established to develop the geospatial zonation of site-specific seismic site effects before considering the local characteristics of site effects dependent on topographic or geological conditions, based on a geospatial big-data platform in Seoul. The zonal conditions were composed of geo-layers, site effect parameters, and other multi-source geospatial maps for each administrative area, and infrastructure was determined based on the integration of the optimized geoprocessing framework.