Due to the unique soil and morphological conditions prevailing in Izmir Bay basin, structural damage has been governed by site effects. Consistently, during October 30, 2020 M7.0 Samos Earthquake, ...which took place offshore of Samos Island, structural damage and life losses were observed to be concentrated in Bayrakli region of Izmir Bay, despite the fact that the fault rupture was at a distance of 65–75 km from the city of Izmir. Additionally, strong ground motions recorded in Izmir Bay showed unique site amplifications that were observed surprisingly at both rock and soil sites. Soil amplifications and duration elongations were mostly due to site effects governed by the response of very deep alluvial deposits of low plasticity. Similarly, due to very extensive faulting-induced fracturing and unusually stratified nature of rock sub-layers, unexpected long period amplifications were also observed at rock sites. These earthquake and site resonance effects were more pronounced in the period range of 0.5–1.5 s. When they were superposed with relatively coinciding natural period of 7–9 story residential buildings of Izmir City, it was concluded that the triple resonance effects among incoming rock ground motions, soil deposits, and the damaged buildings, amplified and prolonged the overall system response. Within the confines of this manuscript, the governing role of site effects leading to increased seismic demand was assessed, through a series of 1D equivalent linear, total stress-based site response assessments, the results of which clearly highlighted the variation of seismic demand in Izmir Bay.
•Samos Island earthquake produced rich long period rock spectral accelerations.•Deep soil sites in Izmir Bay, amplified these long period rich rock motions.•Due to resonance effects, 7-9 story buildings were subjected to larger shakings.•Site effects increased seismic demand and prolonged shaking duration.•These, along with poor design-construction practices caused structural damage.
The 2020 M7.0 Samos earthquake had occurred on the north of Samos Island; however, structural damage was observed in İzmir-Bayraklı, which is located approximately 65 km away from the epicenter. ...Strong ground motions recorded in İzmir Bay showed unique site amplifications, mostly due to the interaction between the basin and deep alluvial deposit response. The objective of this study is to evaluate the predictive performance of current ground motion models (GMMs) for estimating the recorded strong motions, especially the recordings over or near the Bayraklı-Bornova basin. 66 strong motion stations from Turkey with rupture distance (RRUP) < 200 km are used in the residual analysis, considering the ambiguities in the magnitude and depth to the top of the rupture estimations. Event terms of the earthquake for tested GMMs are found to be small and lie within the expected scatter, except for T = 0.5–1.5 s spectral accelerations. Event-specific distance attenuation for RRUP<100 km is consistent with the median predictions of current GMMs; however, the distance scaling for 100 km<RRUP<200 km are significantly different at high frequencies, indicating faster attenuation for Southwestern Anatolia. Relatively long period (0.5–1.5 s) spectral energy is present in both soft sites on the Bayraklı-Bornova basin and rock/stiff-soil sites on the basin edge and these stations contribute significantly to the positive event terms at T = 0.5–1.5 s. For sites within the basin or close to the basin edge, factors such as the direction of the rupture front, basin width and depth, and the seismic structure of the basin contribute to the ground motion variability.
•The structural damage from 2020 Samos Eq. was observed in İzmir-Bayraklı, which is located 65 km away from the epicentre.•The event terms of the earthquake are found to be small, except for T=1 sec, based on the analysis of 66 stations from AFAD.•Distance scaling at high frequencies indicates faster attenuation when compared to current GMMs for large distances.•Mid-period (0.5-1.5 sec) spectral energy is present in soft sites over the İzmir basin and rock sites on the basin edge.•For sites within the basin or close to the basin edge, the variability in recorded ground motions is significant.
On January 24, 2020, Sivrice–Elazig–Turkey earthquake occurred along the East Anatolian Fault Zone. The moment magnitude of the event was reported as 6.8. This paper documents reconnaissance findings ...performed immediately after the event. Investigated sites namely, Lake Hazar shores, Karakaya Dam Reservoir–Euphrates River shores, Malatya–Battalgazi district and its villages, and Elazig Downtown are predicted to be shaken by rock peak ground acceleration, PGA
VS30=1100 m/s
, levels of 0.12–0.42 g, 0.05–0.11 g, 0.05 g, and 0.08 g respectively. The documented geotechnical field performances vary from widespread liquefaction-induced sand boils and lateral spreading, to no signs of surface manifestations of permanent ground deformations or soil liquefaction. In Battalgazi district and Elazig Downtown, the foundation performances vary from no signs of permanent ground deformations to 1–3 cm settlements, and 1–2 cm lateral movements. Additionally, the hydraulic structures inspected are estimated to be shaken by PGA
VS30=1100 m/s
levels of 0.03–0.23 g. Other than a minor longitudinal cracking along a limited section along the crest of a homogeneous earthfill dam, no apparent signs of permanent ground deformations were reported. Last but not least, a number of rock falls were mapped, based on back analyses of which probable peak ground velocities at these rockfall sites were speculated.
A database, which consists of maximum and minimum void ratio limits and their range, particle size, distribution and shape characteristics, is compiled. More specifically, minimum and maximum void ...ratios (emin and emax) along with their range (emax-emin), particle roundness (R) and spherecity (S), fines content (FC), coefficient of uniformity (Cu), mean grain size (D50) data are compiled from natural cohesionless soils and reconstituted grained material (e.g.: rice, glass beads, mica) mixtures. The final dataset is composed of 636, mostly soil samples. Out of 636 samples, 496, 474 and 603 of them have emax, emin or emax-emin data, respectively. Similarly, for 593, 419, 171, 126 and 93 soils, D50, Cu, R, S and FC data exists, respectively. Not for every sample, USCS based soil classification designation is available, hence for the missing ones, soil classification is performed based on mean particle diameter-based classification as suggested by ASTM D2487 – 17: Standard Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System) 1. The dataset consists of 19 silts and clays, 527 sands (357 fine sands, 153 medium sands, 17 coarse sands) and 47 gravels (44 fine gravels, 3 coarse gravels). A spreadsheet summary of the dataset is provided. This dataset is later used for the development of probability-based void ratio predictive models.
This data article provides a summary of seismic soil liquefaction triggering and non-triggering case histories, which were compiled, screened for data completeness and quality, and then processed for ...the development of triggering relationships proposed in “SPT-based probabilistic and deterministic assessment of seismic soil liquefaction triggering hazard” 1. The database is composed of 113 liquefaction, 95 non-liquefaction, and 2 marginal liquefaction case histories, from seismic events with moment magnitude Mw values varying in the range of 5.9 to 8.3. A spreadsheet summary of these case histories are included along with a separate spreadsheet, by which maximum likelihood assessment was performed. These data transparently enable researchers to access case history input parameters and processing details, and to compare the case history processing protocols with the ones of different researchers (e.g.: “The influence of SPT procedures in soil liquefaction resistance evaluations.” 2, “SPT-based liquefaction triggering procedures.” 3).
The void ratio limits and their range are mostly governed by their grain size, distribution, particle shape and fabric for cohesionless soils. For the purpose of developing a probability-based ...predictive model, a database, which consists of minimum and maximum void ratios, their range, as well as particle morphology (roundness, sphericity), size and distribution (mean grain size, fines content and coefficient of uniformity) parameters, is compiled. A set of predictive models, which use the combinations of Cu, D50, FC, R, and S parameters, is proposed. The models with Cu and/or D50, R and S, produce the most precise predictions. The probabilistic forward use of the proposed models is illustrated by a practical example. They are also presented in the form of deterministic chart solutions, illustrating the variation of in-situ void ratios for varying density states as functions of uniformity coefficient or mean grain size.
•A database consisting of emax and emin, grain shape (R, S), size and distribution (D50, FC & Cu) parameters, is compiled.•Probability-based predictive models, which use the combinations of Cu, D50, FC, R, and S parameters are proposed.•Deterministic in-situ void ratio vs. Cu or D50 and DR chart solutions are presented.•The probabilistic forward use of the proposed models is illustrated with a practical example.
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Probabilistic and deterministic seismic soil liquefaction triggering methodologies are proposed in Cetin et al. 1. This manuscript: i) presents the protocols, which need to be ...followed for the correct use of this methodology for forward engineering (design) assessments, ii) guides the engineers through the procedure, and iii) discusses the “tricks” alongside the protocol. An illustrative soil profile shaken by a scenario earthquake is presented, through which consistent estimations of representative SPT blow-counts along with fines content are discussed. Additionally, the estimation of CSR input parameters are illustrated. Last but not least the uncertainty estimations of these input parameters are presented along with the probability and factory of safety for the assessment of liquefaction triggering.
•A simplified methodology and its use to assess liquefaction triggering hazard of a soil site under an earthquake scenario event.•The consistent and unbiased mean estimates of input parameters of SPT blow-counts(N1,60), fines content (FC), vertical effective (s'v) and total (sv) stresses, maximum ground acceleration (amax), stress reduction (or non-linear shear mass participation) factor (rd) and moment magnitude (Mw) along with their uncertainties are discussed.•Outlined methodology enables engineers to estimate the probability of- and factor of safety against- seismic soil liquefaction triggering for design problems.
This study serves as an update to the Cetin et al. (2000, 2004) 1,2 databases and presents new liquefaction triggering curves. Compared with these studies from over a decade ago, the resulting new ...Standard Penetration Test (SPT)-based triggering curves have shifted to slightly higher CSR-levels for a given N1,60,CS for values of N1,60,CS greater than 15 blows/ft, but the correlation curves remain essentially unchanged at N1,60,CS values less than 15 blows/ft. This paper addresses the improved database and the methodologies used for the development of the updated triggering relationships. A companion paper addresses the principal issues that cause differences among three widely used SPT-based liquefaction triggering relationships.
•Addresses the improved database and the methodologies used for the updated triggering relationships.•Discusses updates to Cetin et al. 2,4 databases.•New SPT-based triggering curves shifted to slightly higher CSR-levels for values of N1,60,CS greater than 15 blows/ft.•The correlation curves essentially unchanged at N1,60,CS values less than 15 blows/ft.•The companion paper addresses the differences among three liquefaction triggering relationships.
The preceding companion paper presented the updating of the seismic soil liquefaction triggering relationship of Cetin et al. 1, and compared the resulting updated relationship with the earlier ...version. In this second paper, a detailed cross-comparison is made between three triggering relationships: (1) Seed et al. 2, as slightly updated by the NCEER Working Group (Youd et al. 3), (2) Boulanger and Idriss 4, and (3) Cetin et al. 5. Differences between these three triggering relationships, and the apparent causes of them are examined. Also studied are the impacts of these differences on levels of conservatism with regard to evaluation of liquefaction triggering hazard, and the resulting risks for engineering projects.
•Differences and the apparent causes between the updated relationship of Cetin et al. (2017) 5 with (1) Seed et al. (1985) 2, as slightly updated by the NCEER Working Group (Youd et al., 2001) 3, (2) Boulanger and Idriss (2012) 4, and (3) Cetin et al. (2004) 1 are examined.•The impacts of these differences on levels of conservatism with regard to evaluation of liquefaction triggering hazard, and the resulting risks for engineering projects are studied.•The governing factors resulting in differences between Boulanger and Idriss (2012) 4, and Cetin et al. (2004, 2017) 1,5 are the use of different i) rd, ii) Kσ relationships in the processing of database, and iii) probabilistic treatment of existing data.•The different location of triggering relationships can be expected to be most significant for engineering projects where, (1) critical strata have representative values of N1,60,CS< 20, (2) site-specific seismic site response analyses are performed to directly calculate CSR values, rather than using the “simplified (rd-based) approach, and/or (3) liquefaction of soils with σ'v significantly greater than 1 atm is of potential concern.
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