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SUMMARY The reliable forecasting of seismic sequences following a main shock has practical implications because effective post-event response is crucial in earthquake-stricken regions, aftershocks can progressively cause increased damage and compound economic losses. In the South Iceland Seismic Zone (SISZ), one of two large transform zones in Iceland where earthquake hazard is the highest, an intense seismic sequence took place during 17–24 June 2000, starting with a ${M}_{\rm{w}}$ 6.4 main shock on 17 June 2000, followed by another ${M}_{\rm{w}}$ 6.5 main shock four days later and on a different fault. Both earthquakes caused considerable damage and incurred heavy economic losses. They were immediately followed by intense aftershock activity on the causative faults and triggered earthquakes as far as 80 km away along the transform zone. To investigate the feasibility of forecasting the progression of such complex sequences, we calibrated a spatio-temporal epidemic-type aftershock sequence (ETAS) clustering model to the June 2000 seismic sequence in the framework of Bayesian statistics. Short-term seismicity forecasts were carried out for various forecasting intervals and compared with the observations, the first generated a few hours after the first main shock and followed by daily forecasts. The reliability of the early forecasts was seen to depend on the initial model parameters. By using an adaptive parameter inference approach where the posteriors from each preceding forecasting interval served as informative priors for the next, the fast convergence of the parametric values was ensured. As a result, the 16–84 percentile range of the forecasted number of events captured the actual number of observed events in all daily forecasts, and the model exhibited a strong spatial forecasting ability, even only a few hours after the main shock, and over all subsequent daily forecasts. We present the spatio-temporal ETAS parameters for the June 2000 sequence as ideal candidates of prior estimates for future operational earthquake forecasting of other Icelandic aftershock sequences. Past seismic sequences need to be analysed retrospectively to confirm the stability of the parameters of this study, effectively enable the application of the Bayesian ETAS model as an operational earthquake forecasting system for aftershocks in Iceland.

This deliverable reports an exhaustive state-of-the-art compilation of the most representative seismic fragility and loss estimation models for the buildings and infrastructure components in the testbeds (TBs in the following) of the TURNkey project, which are:TB1-Bucharest (Romania), TB2-Pyrenees (France), TB3-Hveragerði (Southern Iceland) and Húsavík (Northern Iceland), TB4-Patras and Aegio area (Greece), TB5-Port of Gioia Tauro (Italy), and TB6- Groningen (Netherlands).This activity is included within the Work Package 4, aimed at developing and harmonizing seismic physical vulnerability and loss estimation models for structures and infrastructure components within a rapid loss prediction framework. Within a broader context, it may be stated that the contents of this deliverable may also be extrapolated as a useful synthesis of the structural vulnerability standing for the entire European territory. In the chapter 2 of the document,adetailed list of the fragility and loss estimation models adopted for building taxonomies and infrastructure components is tabulated together with their associated publication/reference and a brief description of the corresponding work. Then, futher important information is syntesized in terms of type, structural typology, intensity measure, damage scale, and the region of applicability referring to each individual fragility/loss model under consideration. In chapter 3, in-depth information and discussion of the vulnerability and loss estimation models presented in Chapter 2 are provided for each TB.Furthermore, background exposure information is also provided. Finally, chapter 4 presents the conclusive summary of the Deliverable.

This report details the procedures that have been applied, developed or improved in Task 4.5 for the rapid estimation of damages and losses after an earthquake event. The report revolves around several actions and technical results, which are organized as follows: • Section 3 summarizes the state-of-the-art of current rapid response algorithms and systems, based on a review by Guérin-Marthe et al. (2021). The SELENA and Armargedom software, coupled with shake-map estimates from WP3, are put forward as one of the technical solutions to be implemented in the TURNkey platform. • Section 4 conducts a benchmark study of two damage estimation methods, namely SELENA (Molina et al., 2010), using fragility functions, and Armagedom (Sedan et al., 2013), using semi-empirical vulnerability indices. Both methods are applied on two case-study areas (Luchon area in TB-2 and Alicante area) and the damage distributions are compared. • Section 5 investigates the impact of various factors (resolution of soil amplification maps and building exposure datasets, influence of ground-motion variability) on the accuracy of the damage estimates when applying earthquake scenarios over built areas. Two case studies are considered, namely the Luchon area (TB-2) and the town of Hveragerði (TB3). • Section 6 introduces a probabilistic framework for near real-time seismic damage assessment that exploits heterogeneous sources of information about the seismic input and the structural response to the earthquake. The value of information provided by various combinations of observations and measurements is quantified. The approach is applied to an arbitrary roadway bridge near Patras (TB-4). • Section 7 introduces a sampling-based Bayesian updating method in order to refine damage and loss estimates from field observations. The method is applicable to large real-world systems, such as extended built areas or real-world infrastructure systems. It is applied to the Luchon area (TB-2), where the damage distribution of common buildings and the connectivity loss of the road network system are estimated in a rapid response context. The Bayesian approach for the updating of damage and loss estimated has been implemented in a R/Matlab code, which is briefly described in the companion Deliverable D4.9.

This report details the procedures that have been applied, developed or improved in Task 3.4 for the rapid generation of ground shaking maps (i.e., shake-maps). The report revolves around several actions and technical results, which are organized as follows:  Section 3 summarizes the state-of-the-art of current shake-map algorithms and systems, based on a review by Guérin-Marthe et al. (2021). The USGS ShakeMap v4 approach is compared to a method based on Bayesian updating, which is put forward as one of the technical solutions to be implemented in the TURNkey platform.  Section 4 is based on previous work carried out in Task 3.3.2: in each TB, various GMMs (Ground-Motion Models) are evaluated and ranked, via different scoring metrics. The selected GMMs may then be used for the generation of shake-maps in each TB.  Section 5 details novel research efforts, where the GMM coefficients are updated in order to match the observations. This approach is useful to rapidly update a GMM in a given area for a given earthquake, so that the updated GMM may be reused for subsequent events (e.g., in a seismic sequence) in order to improve the accuracy of ground-shaking estimates. Two parallel and complementary methods are presented, namely a direct calibration of the coefficients (EUC) and a Bayesian updating of the uncertain coefficients in the shake-map (BRGM).  Section 6 discusses site amplification models that are available in each TB: besides local models, Vs30 maps generated at the European level (in the European project SERA) are extracted for each TB. Recommendations are given for each TB on which model should be applied, and whether the SERA model represents a satisfying approximation.  Section 7 explores additional sources of observations that may be used to characterise shake-maps: collection and aggregation of felt reports by EMSC; and extraction of Twitter data and integration as soft evidence in the shake-maps by BRGM. The Bayesian approach for the derivation of shake-maps has been implemented in a Python code, which is briefly described in the companion deliverable report D3.9.

New models are developed for the prediction of vertical-to-horizontal (V/H) spectral ratios of peak ground acceleration (PGA), peak ground velocity (PGV), and 5%-damped elastic response spectra for periods ranging from 0.01 to 10 s. The models use moment magnitude, source-to-site distance, style-of-faulting (SoF), and site classification terms as independent variables. The study is based on a well-compiled Iranian ground-motion databank, consisting of 1350 (*3) three-component accelerograms generated by 370 earthquakes. Only records with known measured time-averaged shear-wave velocity in the uppermost 30 m (VS30) are used for regression analyses. The presented models are valid for moment magnitude ranging from 4.5 to 7.4, distance up to 200 km, and for earthquakes with reverse and strike–slip fault mechanisms. Four alternative mathematical forms are evaluated in terms of magnitude and distance in order to find the optimal functional form for reliable prediction of V/H ratios. Out of four proposed forms, two were chosen for further investigation. The point source (hypocentral and epicentral) as well as extended source (rupture and Joyner-Boore) distance metrics are employed to derive four models. The overall validity of the proposed models is examined by detailed residual analyses as well as comparison with some of the local and regional predictive V/H models. Our proposed models showed significant reduction in the total standard deviation across all periods. The proposed V/H models facilitate assessment of vertical components of response spectrum where horizontal component of response spectrum is known, using V/H spectral ratios as scaling factors.

We present an objective technique for assessing the fundamental resonance frequency ( $${\text{f}}_{0}$$ ) of a given site through horizontal-to-vertical (H/V) spectral ratio. H/V spectral ratios have been determined from 5%-damped spectral acceleration derived from strong-motion time histories recorded at accelerograph stations. The technique has been applied to an updated comprehensive strong ground-motion database from Iran. In this study, the resultant $${\text{f}}_{0}$$ values have been also evaluated through visual inspection of average H/V response spectral ratios for each station as well as detailed inspection of vertical and horizontal spectral components of all events recorded at each station. The technique has been applied to 389 stations of the Iran Strong Motion Network (ISMN), from which $${\text{f}}_{0}$$ values have been determined for 266 stations. The determined $${\text{f}}_{0}$$ values have been used to estimate time-averaged shear-wave velocity in the upper 30 m ( $${\text{V}}_{{{\text{S}}30}}$$ ), taking into account the correlation between H/V parameters and measured $${\text{V}}_{{{\text{S}}30}}$$ values at recording stations. Results and corresponding model uncertainties have been compared with other related studies conducted for Japan, Central and Eastern North America as well as a global model. In comparison with other datasets, the Iranian $${\text{V}}_{{{\text{S}}30}}$$ model shows the highest $${\text{V}}_{{{\text{S}}30}}$$ values among all models. We use the region-specific equation developed in this study to estimate $${\text{V}}_{{{\text{S}}30}}$$ values for 63 stations of ISMN where no other site characterization was available.

TURNkey Deliverable D 5.2 (Phase 1+ Phase 2) Report on recommendations on Community Resilience and Recovery Models &nbsp

This study proposes a new approach to incorporate motion duration in incremental dynamic assessments. In the proposed methodology, at each intensity level, a simulation-based approach, which is verified with actual data, is employed to determine the median duration and the median acceleration spectra of ground motions expected to occur at the site. Afterward, at each intensity level, artificial or spectrally matched motions are produced based on the median acceleration spectra and the median duration, indicating that different intensity levels are directly covered by the generated artificial or adjusted motions rather than just scaling up and down a set of recorded ground motions. In the proposed methodology, duration and acceleration spectral shape changes against intensity level while they remain the same for different intensity levels in approach where responses are derived by scaling up and down of a set of ground motions. The functional relationship between duration and seismic intensity level, which is vital for the estimation of median duration at each intensity level, is firstly investigated for the sites with different soil conditions and rupture distances. Not only is it demonstrated that the data can fit into exponential functions, but the sensitivity of the functions against different parameters is also explored as well. The proposed duration-consistent incremental seismic assessment is used in nonlinear seismic assessment of two single degree of freedom structures, with and without a degrading behavior capability. It is revealed that when changes in duration and spectral shape of the motions at different intensity levels are considered in the nonlinear dynamic analysis, an impactful influence that cannot be easily ignored is witnessed in the structural responses of incremental analyses., It is the first revised version of the paper submitted to the Journal of Engineering Structures