High Seismic Hazard Research Articles

Characterizing Seismogenic Fault Structures of the Lake Pertusillo Reservoir Induced Seismicity (Southern Italy) Using a Relocated Template‐Matching Catalog

AbstractWe present a detailed analysis of the small magnitude (ML < 3) Reservoir Induced Seismicity associated with the Pertusillo water reservoir located in the high seismic hazard zone of Val d'Agri (Southern Italy). We apply template‐matching detection to a 13‐month‐long dense passive survey, obtaining a final high‐precision double‐difference catalog of 5,070 earthquakes (−0.7 < ML < 2.6, MC = 0.2). The new catalog allows precisely tracking the spatiotemporal distribution of the swarm‐seismicity and to map the b‐value of the Gutenberg‐Richter law. We combine seismicity data with available subsurface geophysical data, fostering an improved interpretation of the induced seismicity. We identify four seismicity‐clusters showing rapid changes in seismic rate which correlate to severe seasonal oscillations. Seismicity unravels new km‐scale faults or better define faults partially‐illuminated by template earthquakes. b‐value shows a significant spatial variability, with very‐high b‐value (up to 2) within areas of distributed seismicity and lower (∼1.3) b‐value for on‐fault seismicity featuring larger magnitude events. Seismicity is confined within a brine‐saturated fractured carbonate reservoir, while earthquake distribution and rate are controlled by the fault architecture and rock properties (e.g., inherited fluid pathways, rock fracturing, pore fluid pressure). In particular, most earthquakes reactivate, with extensional kinematics, pre‐existing reverse/transpressional faults favorably oriented in the present‐day extension. All observations suggest that a poroelastic stress transmission mechanism, due to the seasonal water level oscillation, can explain the Pertusillo lake seismicity. This study confirms the importance of investigating the complex interaction among stress changes caused by human activities, pre‐existing faults and local stress field to correctly assess the hazard posed by induced seismicity.

Potential seismic landslide hazard and engineering effect in the Ya’an-Linzhi section of the Sichuan-Tibet transportation corridor, China

The Sichuan-Tibet transportation corridor is located at the eastern margin of the Qinghai-Tibet Plateau, where the complex topography and geological conditions, developed geo-hazards have severely restricted the planning and construction of major projects. For the long-term prevention and early control of regional seismic landslides, based on analyzing seismic landslide characteristics, the Newmark model was used to carry out the potential seismic landslide hazard assessment with a 50-year beyond probability 10%. The results show that the high seismic landslide hazard is mainly distributed along large active tectonic belts and deep-cut river canyons, and are significantly affected by the active tectonics. The low seismic landslide hazard is mainly distributed in the flat terrain such as the Quaternary basins, broad river valleys, and plateau planation planes. The major east-west linear projects mainly pass through five areas with high seismic landslide hazard: Luding-Kangding section, Yajiang-Xinlong (Yalong river) section, Batang-Baiyu (Jinsha river) section, Basu (Nujiang river) section, and Bomi-Linzhi (eastern Himalaya syntaxis) section. The seismic action of the Bomi-Linzhi section can also induce high-risk geo-hazard chains such as the high-level glacial lake breaks and glacial debris flows. The early prevention of seismic landslides should be strengthened in the areas with high seismic landslide hazard.

2022 Mw 6.6 Luding, China, Earthquake: A Strong Continental Event Illuminating the Moxi Seismic Gap

Abstract On 5 September 2022, an Mw 6.6 strike-slip earthquake occurred in Luding, Sichuan, China. It illuminates the seismic gap on the southern end of Xianshuihe fault zone, that is Moxi segment, and is the most damaging earthquake in Chinese Mainland since 2014. In this article, we use multiple seismological methods to analyze the basic characteristics of the Luding earthquake, including its source parameters, rupture process, aftershock distribution, and further discuss its implications on preseismic fault behavior and impact on short-term seismic hazard. Using near-field stations, we first revisit the source parameters of the mainshock and obtain a much shallower hypocentral depth (∼9.3 km) than previously reported. Next, we jointly inverse the teleseismic P-wave data and near-field strong-motion data to constrain the mainshock rupture process. The coseismic slip consists of two subevents that spans for ∼20 km and shows an overall unilateral rupture to the south-southeast direction. The earthquake has 90% of the seismic moment released in its first 10 s. Third, we relocate the first 34 days of aftershocks with both manual phase picks and cross correlation, and finally obtain 5269 well-located events. The aftershocks reveal a near-vertical Xianshuihe fault and two sets of unmapped faults off the major Xianshuihe fault: one set of strike-slip faults on the north-northwest of rupture and the other one on the west of mainshock that generates the most intense seismicity with prevalent normal faulting. By examining the aftershock evolution and Coulomb stress change, we find that postseismic processes evolve both on and off the major fault, and the western off-fault system has highly variable fault orientations. Finally, we calculate the Coulomb stress change by the Luding earthquake on surrounding faults. Results show that the north Anninghe fault is significantly loaded by the Luding earthquake (>0.1 MPa), which poses high seismic hazard in the short term.

Multi-Hazard Analysis in Gunungkidul Regency Using Spatial Multi-Criteria Evaluation

This study has two aims: to determine the spatial distribution of multi-hazard levels and to discover the interactions, interdependencies, and effects that cascade among hazards in Gunungkidul Regency, Special Region of Yogyakarta. A multi-hazard map was created with a scale of 1:250,000 and modelled using SMCE (Spatial Multi-Criteria Evaluation). The conditioning factors used included slope, rainfall, historical data, river distance, geomorphology, land cover, lithology, and fault distance. The selected conditioning factors for each hazard were then weighted using weighted overlay analysis. The results showed that the area of Gunungkidul can be included in the high-risk category for floods, since the probability of flooding is 56.72%, the probability of landslides is 9.14%, that of drought is 48.86%, and that of seismic disturbance is 20.83%. (Multi-hazard maps are created by overlaying flood, landslide, seismic, and drought hazard maps.) After these risk factors were calculated, the regions on the multi-hazard map were re-categorized into five hazard classes. All areas in Gunungkidul Regency have multiple hazards, with risk factors of different magnitudes. The interaction between hazards can generate new hazards that are called cascading hazards. The cascading hazards in the study area are most likely to occur in the north of Gunungkidul Regency with its very high seismic and landslide hazard risk factors, due to the geological and geomorphological conditions of the Baturagung Structural Hills.

The Increasing Coastal Urbanization in the Mediterranean Environment: The State of the Art in Italy

This paper describes the state of the art of urbanization in Italian coastal areas in 2021, both at national and regional level. Moreover, we focused on six coastal municipalities, aiming to evaluate land consumption in relation to population dynamics between 2012 and 2021 and assessing per capita consumed land in each municipality. Finally, an analysis of land consumption in specific areas prone to natural risks along the coastline (hydraulic, landslide and seismic, hazard) was provided. We considered areas of medium hydraulic hazard, of high and very high landslide hazard, and of high and very high seismic hazard. The results indicate an intense process of urbanization in the first 1000 m from the coastline at national, regional, and municipal levels, which is also increasing in the presence of stabilization or dwindling inhabitants. Furthermore, urbanization is also affected by geomorphology, leading to the developments of settlements in the most accessible areas, such as coastal plains, without taking into consideration the presence of natural hazards. The study highlights the importance of monitoring land consumption to the understanding of processes related to urbanization in coastal areas, from the perspective of future effective policies and to support sustainable planning.

Performance of Base-Isolated RC School Building under Blast Loading

It is known that bomb-laden vehicles target many buildings as a result of terrorist activities. The effects of such attacks must be reduced and structures must be protected against blast effects. In high seismic hazard regions, buildings are designed to be earthquake resistant. One of the methods used to dampen earthquake effects on structures is base isolation. Base isolation is effective in distributing blast loads to the structure, similar to seismic loading. In this study, the effects of this distribution on the structure will be evaluated. The scope of the study encompasses the numerical estimation of explosive loads at different distances according to the explosive material carrying capacity of various vehicles and their effects on structures. Linear and nonlinear analysis methods were used to compare the dynamic behaviour of school buildings designed with and without base isolators. The Turkish Building Earthquake Code (2018), which includes the maximum seismic loads, was used in the design of the isolators. Numerical analysis was performed using SAP2000 software based on the finite element method. The blast loads were applied to the floors of the building using the direct integration method in the time domain. FEMA standards were used to determine the blast loads and the performance was evaluated in comparison with the numerical analysis results. As a result of the study, it was concluded that structures with base isolators are efficient in reducing the effects of an explosion at certain distances and these distances will affect the design of the shelter walls.

Preconditioning the 2023 Kahramanmaraş (Türkiye) earthquake disaster.

The 2023 Kahramanmaraş earthquakes occurred on active faults that were known to be a high seismic hazard, yet the devastating impacts of these earthquakes show that the risk was not adequately considered. Vulnerabilities arising from exposure, corruptionand poverty led to a lack of seismic preparedness which amplified the earthquake risk into a tragic disaster.

Contribution to the seismic microzonation of Lisbon based on the integration of geological, geophysical, and geotechnical data

Lisbon has been affected by several moderate to strong earthquakes that caused considerable damage and produced significant economic and social impacts (e.g., the November 1st, 1755, earthquake). Studies on the potential damage due to a seismic event have been done considering Lisbon's moderate to high seismic hazard, but the seismic site effects have not yet been investigated at the city scale. The local ground conditions can locally modify the characteristics of surface seismic motion.Based on a multidisciplinary dataset composed of surface geology, a geotechnical database, and a geophysical database that compiles all the available geophysical tests carried out in Lisbon, an integrated approach to seismic ground characterisation was performed.A regression analysis of the shear-wave velocity values compiled in the geophysical database was done for each geological unit. The peak frequency distribution in the city, assessed from the ambient vibration measurements, showed a pattern in peak frequency variation. It decreases from the oldest to the most recent geological formations that outcrop in the SW-NE direction. Three zones based on peak frequency value distribution were proposed.An estimation of the impedance contrast depths was computed through two processes, considering the previous results: (i) the shallower contrast depth was assessed through a sharp variation of NSPT values available in the geotechnical database, and (ii) the deeper contrast depth was estimated based on geology data and deep borehole information. The results showed that for the upper ∼100 m of depth, a consistent relationship between the contrasts identified through different data was obtained, even if uncertainty increased with depth.

Source mechanisms and induced seismicity in the Val d'Agri Basin (Italy)

SUMMARY We present the results from a fully unconstrained moment tensor inversion of induced seismic events in a complex and high seismic hazard region (Val d'Agri basin, Southern Italy). The study area hosts two well-documented cases of induced microseismicity linked to (i) a wastewater injection well of a giant oilfield (the largest in onshore Europe), and (ii) severe seasonal level changes of an artificial lake. In order to gather information on the non-double-couple components of the source and to better understand the rupture mechanisms, we analyse seismic events recorded during daily injection tests in the disposal well. The computed moment tensors have significant non-double-couple components that correlate with the well-head injection pressure. The injection parameters strongly influence the rupture mechanism that can be interpreted as due to the opening/closing of a fracture network inside a fault zone of a pre-existing thrust fault. For the case of the reservoir-induced seismicity, no direct correlations are observed with the loading/unloading of the reservoir.

New seismic monitoring center in South America to assess the liquefaction risk posed by subduction earthquakes

The east of Cali is composed of loose sand deposits with high water table levels. This condition and the high seismic hazard of the city make cyclic liquefaction one of the main hazards in the city, which may affect more than 600,000 citizens and important infrastructures such as the city’s main drinking water treatment plants. Therefore, it was decided to design and implement a seismic monitoring center to study the behavior of liquefiable soils under local seismogenic conditions, in which subduction earthquakes predominate. First, more than 130 earthquakes from two seismic monitoring centers with liquefiable layers in the USA were studied to determine the requirements for the adequate design of the monitoring center. Then, a robust geotechnical and seismic characterization of the study area including SPT, CPTu, and seismic and ambient noise tests were carried out. From this information, the specifications and location of the instruments and, in general, the characteristics of the monitoring center were defined. The monitoring center has been planned to be established in two stages, and the first one has already been built and commissioned. The implementation of the first stage allowed to adequately record 35 earthquakes from different seismogenic sources, most of them from subduction earthquakes, and to verify that the potentially liquefiable layer remains saturated throughout the year. Subsequent ground motion sensors will allow to deeply study and understand large shear strains and excess pore pressures generation in the soil deposit, as well as their relationships with different intensity measures. The experience shared herein can benefit the design, construction, and operation of other seismic monitoring centers across the world.

A fault-based probabilistic seismic hazard model for Lebanon, controlling parameters and hazard levels

The present work develops a comprehensive probabilistic seismic hazard study for Lebanon, a country prone to a high seismic hazard since it is located along the Levant fault system. The historical seismicity has documented devastating earthquakes which have struck this area. Contrarily, the instrumental period is typical of a low-to-moderate seismicity region. The source model built is made of a smoothed seismicity earthquake forecast based on the Lebanese instrumental catalog, combined with a fault model including major and best-characterized faults in the area. Earthquake frequencies on faults are inferred from geological as well as geodetic slip rates. Uncertainties at every step are tracked and a sensitivity study is led to identify which parameters and decisions most influence hazard estimates. The results demonstrate that the choice of the recurrence model, exponential or characteristic, impacts the most the hazard, followed by the uncertainty on the slip rate, on the maximum magnitude that may break faults, and on the minimum magnitude applied to faults. At return periods larger than or equal to 475 years, the hazard in Lebanon is fully controlled by the sources on faults, and the off-fault model has a negligible contribution. We establish a source model logic tree populated with the key parameters, and combine this logic tree with three ground-motion models (GMMs) potentially adapted to the Levant region. A specific study is led in Beirut, located on the hanging-wall of the Mount Lebanon fault to understand where the contributions come from in terms of magnitudes, distances and sources. Running hazard calculations based on the logic tree, distributions of hazard estimates are obtained for selected sites, as well as seismic hazard maps at the scale of the country. Considering the PGA at 475 years of return period, mean hazard values found are larger than 0.3 g for sites within a distance of 20–30 km from the main strand of the Levant Fault, as well as in the coastal region in-between Saida and Tripoli (≥ 0.4 g considering the 84th percentile). The study provides detailed information on the hazard levels to expect in Lebanon, with the associated uncertainties, constituting a solid basis that may help taking decisions in the perspective of future updates of the Lebanese building code.

Performance of Medium-Rise Buildings with Reinforced Concrete Shear Walls Designed for High Seismic Hazard

This work has evaluated the collapse fragility of a typical Chilean building for residential use, structured based on shear-resistant RC walls and inverted beams arranged along its entire perimeter, using the incremental dynamic analysis (IDA) for the evaluation of its structural behavior, using for this the 2018 version of the SeismoStruct software. This method evaluates the global collapse capacity of the building from the graphical representation of its maximum inelastic response, obtained through a non-linear time-history analysis, against the scaled intensity of a set of seismic records obtained in the subduction zone, thus creating the IDA curves of the building. The processing of the seismic records is included within the applied methodology to make them compatible with the elastic spectrum of the Chilean design, achieving an adequate seismic input in the two main structural directions. In addition, an alternative IDA method based on the elongated period is applied to calculate the seismic intensity. The results of the IDA curve obtained with this procedure and the standard IDA analysis are analyzed and compared. The results show that the method relates very well to the structure's demand and capacity and confirms the non-monotonous behavior exposed by other authors. Regarding the alternative IDA procedure, the results indicate that the method is inadequate, failing to improve the results obtained by the standard method.

Energy-based modelling of in-plane fragility curves for the 2D ultimate capacity of Italian masonry buildings

The high seismic hazard of the Italian territory and the vulnerability of its historic masonry heritage require the development of fragility curves that must be increasingly reliable and robustly correlated to exposure. To date, national-scale seismic risk analyses mainly use empirical curves derived from the statistical analysis of damage induced by past events. These curves have shown good reliability, but they correlate only with a few typological-structural characteristics of the building, such as the number of floors, the vertical structure typology or the construction period. The present research paper aims to overcome this limitation with a hybrid approach that provides a better exposure characterisation. Specifically, the proposed strategy integrates the SAVE and Piecewise Rigid Displacement (PRD) methods. SAVE is an empirical approach based on the damage assessment due to past seismic events used to identify a seismic behaviour of a structure, while the PRD method is a numerical approach that solves the boundary value problem for normal, rigid, no-tension material. It can model different structural typologies, and as a result, it also provides the value of the horizontal static multiplier that drives the masonry construction to collapse. An extended numerical campaign is carried out considering a sample of 750 masonry buildings distributed throughout the Italian territory and extracted from the PLINIVS typological database. Looking at each construction, first, a PRD analysis is conducted to define its seismic capacity, paying special attention to modelling construction details. After that, the SAVE method is used to classify the construction in a specific seismic vulnerability class, i.e., from A to C, with decreasing vulnerability. All the buildings belonging to the same class are then collected, and three fragility curves representative of the collapse state (one for each vulnerability class) are derived and validated against empirical and analytical ones commonly adopted in the Literature. The integrated methodology shows a good agreement between simulations and observations, confirming the viability of the proposed hybrid methodology for the large-scale assessment of masonry buildings, providing an effective strategy to plan mitigation and rehabilitation interventions.

Spatial variations of Rn and CO2 emissions in the Wuzhong–Lingwu region, northwest China

Soil gas Rn and CO2 in surface rupture and deep-seated fault zones are important indicators for tectonic and seismic activities. The spatial distributions of Rn and CO2 concentrations and their relationships with earthquakes and stress state in the Wuzhong–Lingwu area of Ningxia, Northwest China, were investigated through field observations based on 76 measurement points, spatial interpolation and six crossing-fault profiles along Yellow River Fault zone (YRF). Observed results of the soil gas Rn and CO2 in different segments of Yellow River Fault zone illustrated that YRF has features of both strike-slip and certain normal fault characteristics. Moreover, the difference in seismic activity could also account for the differences in gas concentration and relative activity intensity (RAI) in the Yellow River Fault zone. Significant differences in the spatial distributions of Rn and CO2 were identified in gridded observation mode. By comparing these spatial distributions with the surface latent heat flux (SLHF), volumetric soil water layer (SWVL), and lithology, an anomalous high-Rn area was identified in the east and south Qingtongxia, and associated with Permian sandstone and mudstone in a piedmont setting. Away from a strong impact of irrigation in the Yinchuan Basin, CO2 anomalies were identified in the transition area between the Yinchuan Basin and the mountains and coincided with a dramatic negative variation of surface latent heat flux, which was considered to reflect humus accumulation, rich organic matter, and strong soil microorganism activity in loosely accumulated mountain alluvial deposits. After excluding gas anomalies related to shallow soils and surface geology, anomalies of Rn and CO2 in the west of Lingwu were consistent with the distribution of low seismic b-values and frequent seismic activity in plane and profile. According to similar studies in the north-south seismic belts, it is believed that high stress and strong seismic activity increased the permeability of rocks and boosted the gas emission in the west of Lingwu. Base on a crustal thickness variation belt, high-velocity bodies, and in this region, an higher seismic hazard was illustrated. This study offers new insight into combining geochemical characteristics of soil gas and seismological methods to estimate regional seismic hazards.

Late-Quaternary paleoearthquakes along the Liulengshan Fault on the northern Shanxi Rift system

The Liulengshan Fault (LLSF), which lies on the northeastern edge of the Ordos Plateau, is a controlling boundary fault in the northern part of the Shanxi Rift system (SRS). The displaced landforms show that the fault has undergone strong and frequent late-Quaternary seismic activities. In 1989 and 1991, two moderate–strong earthquake swarms (Ms=6.1 and Ms=5.8) successively occurred in the LLSF, and GPS velocity shows that the areas are extending at around 1–2 mm/a. However, there is no surface-rupturing earthquake reported on the LLSF in historical records. Thus, the study of paleoseismic history and rupture behavior of paleoearthquakes in late-Quaternary on the LLSF is of fundamental importance for understanding the future seismic risk of this fault. To solve these problems, we conducted paleoseismological trench excavations at two sites on the LLSF to establish its paleoearthquake history. On the basis of the field geological survey and interpretation of high-precision topographic data, we carried out large-scale fault mapping and excavated two trenches in Xujiabao and Luofengwa across the LLSF. Then, four events in the Xujiabao trench and three events in the Luofengwa trench are identified. Finally, combined with radiocarbon dating (C14), optically stimulated luminescence (OSL) and OxCal modeling, we constrained the ages of these events. Together with the previous results of paleoseismology inYin et al. (1997), we consider that different segments of the LLSF may rupture together at the same time. Therefore, a total of six paleoearthquake events since late-Quaternary have been finally confirmed at 44,151–30881a, 40,163-28045a, 28,233-19215a, 16,742-12915a, 12,788-8252a, and 8203–2300a BP. According to the empirical relationships between moment magnitude and rupture length, the best estimated magnitude is inferred to be in the range between Mw 6.9 and Mw 7.7. Considering the strong late-Quaternary activity and a long earthquake elapsed time, we propose that the LLSF might have a high seismic hazard potential in the near future.

Extended Tromograph Surveys for a Full Experimental Characterisation of the San Giorgio Cathedral in Ragusa (Italy).

Geophysical surveys are widely used to reconstruct subsoil seismo-stratigraphic structures with a non-invasive approach. In this study the geophysical surveys were carried out with the aim to characterise the San Giorgio Cathedral in Ragusa (Italy) and the area on which it is built from a dynamic point of view. A 3D subsoil model was realised through the integration of two active (i.e., seismic tomography and multichannel analysis of surface waves) and one passive seismic technique (horizontal to vertical spatial ratio). The instrumentation used for the latter method consists of a tromograph (Tromino®), which is also employed for the characterisation of the building, focusing on the façade and the dome, by means of an ambient vibration test, processed through the standard spectral ratio and frequency domain decomposition methods. Integration of the 3D model, showing the distribution of areas with different physicomechanical characteristics, enables identifying anomalies that are likely attributable to the remains of the ancient Byzantine church of San Nicola. Four lower modes mainly involving the two investigated macroelements are identified. The experimental results outline the advantages of the use of the tromograph both for soil and structural characterisation, especially for massive masonry buildings located in areas with high seismic hazard.

A Bayesian-based data fusion methodology and its application for seismic structural health monitoring of the Consoli Palace in Gubbio, Italy

Recent earthquakes have demonstrated that monumental structures located in regions characterized by high seismic hazard are particularly sensitive to damage, stimulating a growing attention to the formulation of cost-effective and long-lasting methods for damage assessment. Generally, the evaluation of a healthy or damaged state is data-driven and it can be subjected to a large amount of uncertainty. In order to associate a damage symptom to an actual structural damage, including all the uncertainties involved in the process, a Bayesian-based data fusion methodology is proposed. To this purpose, different sources of information are combined, such as dynamic structural properties extracted from monitoring data (natural frequencies and mode shapes), static response data (crack amplitudes) and visual inspections. More in depth, the proposed procedure comprises three fundamental steps: i) calibration of a finite element (FE) model, partitioned in well-thought-out macro-elements on the basis of engineering judgments and/or numerical simulations and, subsequently, construction of a tuned surrogate model (SM) considering pre-selected uncertain parameters as inputs, such as the Young's modulus, shear modulus, Poisson's ratio and mass density associated to each macro-element; ii) solve the Bayesian-based inverse problem aimed at deriving the posterior statistics of the uncertain parameters over the space of the surrogate model's classes in a computational effective manner by using dynamic data; iii) adjust the posterior distribution on the basis of the information obtained from static data and visual inspections, i.e., data fusion. The suitability of the proposed approach is demonstrated by using the monitoring data pertaining to a monumental palace, located in Gubbio (Italy) and named Consoli Palace, which has been monitored by the Authors since 2017.

Seismic vulnerability assessment and retrofitting design of Italian public buildings

Rina Consulting, between 2019 and 2021 was involved in the seismic vulnerability assessment and retrofit design of a large public buildings stock in Italy. The project includes several buildings built between the 40′s and the 90′s located in regions prone to very high seismic hazard and characterized by strategic uses. The buildings included in the portfolio span from masonry structures to reinforced concrete structures, including precast buildings. All the structures were submitted to linear and nonlinear analysis to define their seismic vulnerability and identify their structural deficiencies; then a retrofit design was performed to guarantee the increase of the building's seismic capacity according to the requirements of National code. Alternative retrofitting scenarios were investigated, and compared by means of cost-benefit analysis, with the aim to guarantee a good balance between the costs and the structural efficiency of the interventions.The main aim of the paper is to present practical considerations regarding the main issues related to the data gathering, the seismic input definition and the seismic vulnerability index obtained for the different building typology. The study aims also to investigate the comparison between the seismic requirements assumed for the original design and the seismic requirements assumed for the seismic vulnerability according to the current national code and its influence on retrofit interventions costs. The collected data form part of a database which scope is to provide a criterion for predicting retrofit strategy and costs as a function of the seismic vulnerability index. Final purpose of the study is to provide possible improvement of the methodologies to be applied to similar projects that include large building stock to define a possible efficient framework to be proposed to the different stakeholders.

Loss-Driven Rapid Warning Methodology for Seismic Risk Mitigation of a Target Railway Infrastructure

Due to historical, geographical and economic conditions, the population of the Italian peninsula live in zones of intermediate and high seismic hazard. Nevertheless, Italy has a railway network that is deployed throughout its national territory as customary in developed countries. This network plays a fundamental role in the Italian economy and contributes to the resilience of the big cities to seismic events. In this direction, an active strategy for seismic risk mitigation is achieved with the use of information systems, which alert the occurrence of a seismic event and, in some cases, estimate the state of damage, at local or territorial scale, and the economic loss (e.g. early earthquake warning, rapid response system, aftershock warning system). However, the seismic hazard scenario of the Italian country, with most of active faults along its central area of the peninsula, makes it difficult to implement a comprehensive seismic early warning system. In response to this situation, this study proposes a Railway Rapid Warning System (RRWS) for a railway viaduct of the Campania region of Italy. The case study viaduct is approximately 1 km long connecting Quarto Centro and Quarto stations of the Circumflegrea line. The decisional phase of the protocol is based on an economic loss minimization criterion in order to prevent both missing and false alarm states as a main requirement to the new generation of information systems. The minimization consists of a multi-cost analysis combining structural, environmental, urban context and other aspects associated with risk mitigation actions. From the point of view of structural vulnerability, the protocol uses dynamic analysis and kinematic analysis based on the viaduct elements. It is important to mention that the end user of the warning protocol is the institution in charge of the management of the viaduct, who receives the alarm from a web page, e-mail and SMS. Additionally, the alarm describes the intensity measure of the earthquake and, above all, immediately recommends a set of seismic risk mitigation actions specifically targeted on actual conditions of the reference structure.

CONSTRUCTION SYSTEM SELECTION IN LOW-BED CAPACITY HEALTH BUILDINGS WITH FUZZY AHP IN EARTHQUAKE ZONES

Purpose: Reconstruction of health buildings that were heavily damaged after the earthquake has become an important issue in Turkey. The negative performance of the construction systems of health buildings after major earthquakes necessitates the evaluation of the building system (CS) options, which can create an alternative to the market, according to various criteria. The main purpose of the study is to develop a systematic basis for the CS of 1816 health institutions to be rebuilt within the scope of the UDSEP 2023 project and to decide between alternatives in Turkey. In this study, the example of a hospital with a low bed capacity (20 beds) was discussed. Method: In the application of the Methodology-Fuzzy Analytical Hierarchy Process (FAHP) method of the research, 40 expert opinions were taken at the stages of planning, construction and inspection of health buildings. Findings: Experts in various fields of the construction industry have determined that CS performance is the primary criterion and cost is the secondary criterion for healthcare buildings in high seismic hazard areas. Conclusion: Among the CS alternatives, Structural Steel Frame (SSF) was determined as the most suitable structural system for earthquake zones.