Earthquake-induced slope instability is one of the major sources of earthquake hazards in near fault regions. Simplified tools, such as Newmark&rsquo
s Sliding Block (NSB) Analysis are widely used to ...represent the stability of a slope under earthquake shaking. The outcome of this analogy is the slope displacement where larger displacement values indicate higher seismic slope instability risk. Recent studies in the literature propose empirical models between the slope displacement and single or multiple ground motion intensity measures such as peak ground acceleration or Arias intensity. These correlations are based on the analysis of large datasets from global ground motion recording database (PEER NGA-W1 Database). Ground motions from earthquakes occurred in Turkey are poorly represented in NGA-W1 database since corrected and processed data from Turkey was not available until recently. The objective of this study is to evaluate the compatibility of available NSB displacement prediction models for the Probabilistic Seismic Hazard Assessment (PSHA) applications in Turkey using a comprehensive dataset of ground motions recorded during earthquakes occurred in Turkey. Then the application of selected NSB displacement prediction model in a vector-valued PSHA framework is demonstrated with the explanations of seismic source characterization, ground motion prediction models and ground motion intensity measure correlation coefficients. The results of the study is presented in terms of hazard curves and a comparison is made with a case history in Asarsuyu Region where seismically induced landslides (Bakacak Landslides) had taken place during 1999 Dü
zce Earthquake.
Projekt usklađivanja karata seizmičke opasnosti za područje Zapadnog Balkana (BSHAP) financiran je 7 godina od strane NATO programa „Science for Peace“ za pripremu novih karata seizmičke opasnosti za ...područje Zapadnog Balkana upotrebom modernih znanstvenih alata. Jedan od najvažnijih rezultata BSHAP programa je ažurirani i jedinstveni BSHAP katalog potresa direktno sastavljen iz baze podataka potresa iz pojedinih regija. U okviru BSHAP-a, znatno je povećana mreža „free-field“ uređaja za snimanje jakog gibanja tla kupnjom novih i postojećih uređaja (akcelerografa), te je BSHAP baza podataka zapisa jakih (akcelerografskih) potresa sastavljena od prijašnjih (većinom analognih zapisa) prije BSHAP projekta, i novih digitalnih zapisa nakon i u toku BSHAP projekta. BSHAP baza podataka jakih gibanja koristi se za odgovarajući odabir relacija za procjenu gibanja tla (GMPE) za procjenu vjerojatnosti potresne opasnosti (PSHA) usporedbom prikupljenih zapisa jakih gibanja s GMPE relacijama na globalnoj, europskoj i Euro-Med razini. U okviru BSHAP-a, prikupljeno je relevantno znanje o geološkoj strukturi jugozapadnog Balkana koje je omogućilo bolje razumijevanje prevladavajućeg smjera napetosti u regiji. Glavni rezultat BSHAP-a su nove karte potresne opasnosti za područje zapadnog Balkana dobivene primjenom pristupa tzv. mreže izglađivanja seizmičnosti. Rezultati su izraženi preko vršnih horizontalnih ubrzanja (PGA) za povratne periode 95 i 475 godina usklađeni s zahtjevima Eurocode 8. Izrađene karte potresne opasnosti u ovom projektu dobra su osnova za opis potresne opasnosti područja zapadnog Balkana. One će pomoći nacionalnim vlastima, javnim i privatnim institucijama, civilnim agencijama za hitne slučajeve i sl., te za urbanističko planiranje, pripremu za prirodnu katastrofu i smanjenje seizmičke opasnosti.
NGA-Subduction research program Bozorgnia, Yousef; Abrahamson, Norman A; Ahdi, Sean K ...
Earthquake spectra,
05/2022, Letnik:
38, Številka:
2
Journal Article
Recenzirano
Odprti dostop
This article summarizes the Next Generation Attenuation (NGA) Subduction (NGA-Sub) project, a major research program to develop a database and ground motion models (GMMs) for subduction regions. A ...comprehensive database of subduction earthquakes recorded worldwide was developed. The database includes a total of 214,020 individual records from 1,880 subduction events, which is by far the largest database of all the NGA programs. As part of the NGA-Sub program, four GMMs were developed. Three of them are global subduction GMMs with adjustment factors for up to seven worldwide regions: Alaska, Cascadia, Central America and Mexico, Japan, New Zealand, South America, and Taiwan. The fourth GMM is a new Japan-specific model. The GMMs provide median predictions, and the associated aleatory variability, of RotD50 horizontal components of peak ground acceleration, peak ground velocity, and 5%-damped pseudo-spectral acceleration (PSA) at oscillator periods ranging from 0.01 to 10 s. Three GMMs also quantified “within-model” epistemic uncertainty of the median prediction, which is important in regions with sparse ground motion data, such as Cascadia. In addition, a damping scaling model was developed to scale the predicted 5%-damped PSA of horizontal components to other damping ratios ranging from 0.5% to 30%. The NGA-Sub flatfile, which was used for the development of the NGA-Sub GMMs, and the NGA-Sub GMMs coded on various software platforms, have been posted for public use.
On October 30, 2020 14:51 (UTC), a moment magnitude (M
w
) of 7.0 (USGS, EMSC) earthquake occurred in the Aegean Sea north of the island of Samos, Greece. Turkish and Hellenic geotechnical ...reconnaissance teams were deployed immediately after the event and their findings are documented herein. The predominantly observed failure mechanism was that of earthquake-induced liquefaction and its associated impacts. Such failures are presented and discussed together with a preliminary assessment of the performance of building foundations, slopes and deep excavations, retaining structures and quay walls. On the Anatolian side (Turkey), and with the exception of the Izmir-Bayrakli region where significant site effects were observed, no major geotechnical effects were observed in the form of foundation failures, surface manifestation of liquefaction and lateral soil spreading, rock falls/landslides, failures of deep excavations, retaining structures, quay walls, and subway tunnels. In Samos (Greece), evidence of liquefaction, lateral spreading and damage to quay walls in ports were observed on the northern side of the island. Despite the proximity to the fault (about 10 km), the amplitude and the duration of shaking, the associated liquefaction phenomena were not pervasive. It is further unclear whether the damage to quay walls was due to liquefaction of the underlying soil, or merely due to the inertia of those structures, in conjunction with the presence of soft (yet not necessarily liquefied) foundation soil. A number of rockfalls/landslides were observed but the relevant phenomena were not particularly severe. Similar to the Anatolian side, no failures of engineered retaining structures and major infrastructure such as dams, bridges, viaducts, tunnels were observed in the island of Samos which can be mostly attributed to the lack of such infrastructure.
Bolu-Ilgaz region was damaged by several large earthquakes in the last century and the
structural damage was substantial especially after the 1944 and 1999 earthquakes. The
objective of this study is ...to build the seismic source characterization model for the rupture
zone of 1944 Bolu-Gerede earthquake and perform probabilistic seismic hazard assessment
(PSHA) in the region. One of the major improvements over the previous PSHA practices
accomplished in this study is the development of advanced seismic source models in terms
of source geometry and reoccurrence relations. Geometry of the linear fault segments are
determined and incorporated with the help of available fault maps. Composite magnitude
distribution model is used to properly represent the characteristic behavior of NAF without an
additional background zone. Fault segments, rupture sources, rupture scenarios and fault
rupture models are determined using the WG-2003 terminology. The Turkey-Adjusted NGAW1
(Gü
lerce et al., 2013) prediction models are employed for the first time on NAF system.
The results of the study is presented in terms of hazard curves, deaggregation of the hazard
and uniform hazard spectrum for four main locations in the region to provide basis for
evaluation of the seismic design of special structures in the area. Hazard maps of the region
for rock site conditions and for the proposed site characterization model are provided to
allow the user perform site-specific hazard assessment for local site conditions and develop
site-specific design spectrum. The results of the study will be useful to manage the future
seismic hazard in the region.
Vertical design spectra may be developed in a probabilistic seismic hazard assessment
(PSHA) by computing the hazard using vertical ground motion prediction equations
(GMPEs), or using a ...vertical-to-horizontal spectral acceleration (V/H) ratio GMPEs to scale
the horizontal spectrum that was developed using the results of horizontal component PSHA.
The objective of this study is to provide GMPEs that are compatible with regional ground
motion characteristics to perform both alternatives. GMPEs for the V/H ratio were developed
recently by Gü
lerce and Abrahamson (2011) using NGA-W1 database. A strong motion
dataset consistent with the V/H ratio model parameters is developed by including strong
motion data from earthquakes occurred in Turkey with at least three recordings per
earthquake. The compatibility of GA2011 V/H ratio model with the magnitude, distance, and
site amplification scaling of Turkish ground motion dataset is evaluated by using inter-event
and intra-event residual plots and necessary coefficients of the model is adjusted to reflect
the regional characteristics. Analysis of the model performance in the recent moderate-tolarge
magnitude earthquakes occurred in Turkey shows that the Turkey-Adjusted GA2011
model is a suitable candidate V/H ratio model for PSHA studies conducted in Turkey. Using
the same dataset, a preliminary vertical ground motion prediction equation for Turkey
consistent with the preliminary vertical model based on NGA-W1 dataset is developed.
Proposed preliminary model is applicable to magnitudes 5-8.5, distances 0-200 km, and
spectral periods of 0-10 seconds and offers an up-to-date alternative to the regional vertical
GMPEs proposed by Kalkan and Gü
lkan (2004).
The primary objective of this study is to evaluate the seismic hazard in the Eastern Marmara Region using improved seismic source models and enhanced ground motion prediction models by probabilistic ...approach. Geometry of the fault zones (length, width, dip angle, segmentation points etc.) is determined by the help of available fault maps and traced source lines on the satellite images. State of the art rupture model proposed by USGS Working Group in 2002 is applied to the source system. Composite reoccurrence model is used for all seismic sources in the region to represent the characteristic behavior of North Anatolian Fault. New and improved global ground motion models (NGA models) are used to model the ground motion variability for this study. Previous studies, in general, used regional models or older ground motion prediction models which were updated by their developers during the NGA project. New NGA models were improved in terms of additional prediction parameters (such as depth of the source, basin effects, site dependent standard deviations, etc.), statistical approach, and very well constrained global database. The use of NGA models reduced the epistemic uncertainty in the total hazard incorporated by regional or older models using smaller datasets. The results of the study is presented in terms of hazard curves, deaggregation of the hazard and uniform hazard spectrum for six main locations in the region (Adapazari, Duzce, Golcuk, Izmit, Iznik, and Sapanca City Centers) to provide basis for seismic design of special structures in the area. Hazard maps of the region for rock site conditions at the accepted levels of risk by Turkish Earthquake Code (TEC-2007) are provided to allow the user perform site-specific hazard assessment for local site conditions and develop site-specific design spectrum. Comparison of TEC-2007 design spectrum with the uniform hazard spectrum developed for selected locations is also presented for future reference.
The objective of this study is to evaluate the regional differences between the worldwide based NGA-W1 ground motion models and available Turkish strong ground motion dataset and make the required ...adjustments in the NGA-W1 models. A strong motion dataset using parameters consistent with the NGA ground motion models is developed by including strong motion data from Turkey. Average horizontal component ground motion is computed for response spectral values at all available periods using the GMRotI50 definition consistent with the NGA-W1 models. A random-effects regression with a constant term only is used to evaluate the systematic differences in the average level of shaking. Plots of residuals are used to evaluate the differences in the magnitude, distance, and site amplification scaling between the Turkish dataset and the NGA-W1 models. Model residuals indicated that the ground motions are overestimated by all 5 NGA-W1 models significantly, especially for small-to-moderate magnitude earthquakes. Model residuals relative to distance measures plots suggest that NGA-W1 models slightly underestimates the ground motions for rupture distances within 100-200 km range. Models including the aftershocks over-predict the ground motions at stiff soil/engineering rock sites. The misfit between the actual data and model predictions are corrected with adjustments functions for each scaling term. Turkey-Adjusted NGA-W1 models proposed in this study are compatible with the Turkish strong ground motion characteristics and preserve the well-constrained features of the global models. Therefore these models are suitable candidates for ground motion characterization and PSHA studies conducted in Turkey.
The Harmonization of Seismic Hazard Maps in the Western Balkan Countries Project (BSHAP) was funded for 7 years by NATO Science for Peace and Security Program to support the preparation of new ...seismic hazard maps of the Western Balkan Region. In the framework of BSHAP, the regional free field strong motion network capacity was significantly increased by deployed recorders (Gülerce et al. in Final report of improvements in the Harmonized Seismic Hazard Maps for the Western Balkan Countries (BSHAP-2) Project, NATO SfP-984374.
http://wbalkanseismicmaps.org/
,
2015
) and the BSHAP strong motion database that includes both pre-BSHAP (mostly analogue) and post-BSHAP (all digital) recordings was compiled. The BSHAP strong motion database includes uniformly processed strong motions along with the related earthquake metadata and station information; therefore, it provides a solid base for the ground motion characterization studies in the region. The established database is used for selection of the ground motion prediction equations (GMPEs) to be employed in the probabilistic seismic hazard assessment by comparing the compiled strong ground motions with the predictions of candidate global and Euro-Mediterranean GMPEs in a systematic manner. Details of the selection strategy including the analysis of model predictions for ground motion scaling, data testing to evaluate the model performance, and ranking is provided here along with the GMPE logic tree used in the proposed seismic hazard maps by Kuka et al. (Bull Earthq Eng, under review).
This article is reply to the comment sent by Carlo Cauzzi and Ezio Faccioli related to the published article “BSHAP project strong ground motion database and selection of suitable ground motion ...models for the Western Balkan Region” by Salic et al. (
2016
).
