scholarly journals A deterministic seismic risk macrozonation of Seville

2021 ◽  
Vol 14 (22) ◽  
Author(s):  
Luis Fazendeiro Sá ◽  
Antonio Morales-Esteban ◽  
Percy Durand Neyra

The seismicity of the southwestern Iberian Peninsula is moderate but large events with long return periods occur (≈ 200 years). This exceeds the life of various generations, making the population unacquainted with the seismic hazard. On the one hand, this results in a low demanding seismic code which increases the seismic vulnerability and, therefore, the seismic risk. On the other hand, the local emergency services must be properly prepared to face a destructive seismic event, with emergency plans and mitigation strategies. This assumption enhances the need of assessing the seismic risk of Seville in a civil protection context. For all the aforementioned and for the lack of instrumental data of relevant earthquakes, the assessment of the seismic hazard in this area is challenging. To do this, seismogenic zones of the new seismic hazard map of Spain have been used as sources. The peak ground acceleration (PGA) for each scenario has been calculated by means of ground motion prediction equations (GMPE). To estimate the site effects, in a 1D model environment, a shear wave velocity (Vs) map of the top 5 m has been depicted based on the standard penetration test (SPT). Seville’s building stock has been classified in agreement with the previous works in Lorca and Barcelona to determine its vulnerability. The main goal of this work was to investigate the influence of the soil amplification on the seismic behaviour of different building typologies. Therefore, the final target was to plot the damage scenarios expected in Seville under a maximum credible earthquake by means of a deterministic seismic hazard assessment (DSHA). As outputs, the scenario modelled showed that around 27 000 buildings would experience a moderate damage and that 26 000 would suffer pre-collapse or even collapse. Thus, approximately 10% of the population would lose their dwellings. Regarding the human loses, around 22 000 people would suffer serious injuries and approximately 5 000 people would die. Owing to these conclusions, this research evidences the crucial need by civil protection services to implement a local emergency plan as a tool to mitigate the probable consequences that arise from this threat.

Author(s):  
A. Sandoli ◽  
G. P. Lignola ◽  
B. Calderoni ◽  
A. Prota

AbstractA hybrid seismic fragility model for territorial-scale seismic vulnerability assessment of masonry buildings is developed and presented in this paper. The method combines expert-judgment and mechanical approaches to derive typological fragility curves for Italian residential masonry building stock. The first classifies Italian masonry buildings in five different typological classes as function of age of construction, structural typology, and seismic behaviour and damaging of buildings observed following the most severe earthquakes occurred in Italy. The second, based on numerical analyses results conducted on building prototypes, provides all the parameters necessary for developing fragility functions. Peak-Ground Acceleration (PGA) at Ultimate Limit State attainable by each building’s class has been chosen as an Intensity Measure to represent fragility curves: three types of curve have been developed, each referred to mean, maximum and minimum value of PGAs defined for each building class. To represent the expected damage scenario for increasing earthquake intensities, a correlation between PGAs and Mercalli-Cancani-Sieber macroseismic intensity scale has been used and the corresponding fragility curves developed. Results show that the proposed building’s classes are representative of the Italian masonry building stock and that fragility curves are effective for predicting both seismic vulnerability and expected damage scenarios for seismic-prone areas. Finally, the fragility curves have been compared with empirical curves obtained through a macroseismic approach on Italian masonry buildings available in literature, underlining the differences between the methods.


2021 ◽  
Author(s):  
Antonio Sandoli ◽  
Gian Piero Lignola ◽  
Bruno Calderoni ◽  
Andrea Prota

Abstract A hybrid seismic fragility model for territorial-scale seismic vulnerability assessment of masonry buildings is developed and presented in this paper. The method combines expert-judgment and mechanical approaches to derive typological fragility curves for Italian residential masonry building stock. The first classifies Italian masonry buildings in five different typological classes as function of age of construction, structural typology, and seismic behaviour and damaging of buildings observed following the most severe earthquakes occurred in Italy. The second, based on numerical analyses results conducted on building prototypes, provides all the parameters necessary for developing fragility functions.Peak-Ground Acceleration (PGA) at Ultimate Limit State attainable by each building’s class has been chosen as an Intensity Measure (IM) to represent fragility curves: three types of curve have been developed, each referred to mean, maximum and minim value of PGAs defined for each buildings class.To represent the expected damage scenario for increasing earthquake intensities, a correlation between PGAs and Mercalli-Cancani-Sieber (MCS) macroseismic intensity scale has been used and the corresponding fragility curves developed.Results show that the proposed building’s classes are representative of the Italian masonry building stock and that fragility curves are effective for predicting both seismic vulnerability and expected damage scenarios for seismic-prone areas. Finally, the fragility curves have been compared with empirical curves obtained through a macroseismic approach on Italian masonry buildings available in literature, underlining the differences between the methods.


2021 ◽  
Author(s):  
Christian R Escudero ◽  
Alejandro Ramirez Gaytan ◽  
Araceli Zamora Camacho ◽  
Adolfo Preciado ◽  
Karen L. Flores ◽  
...  

Abstract We performed a seismic vulnerability assessment that involves geotechnical and building structure analysis for Puerto Vallarta, Mexico, a city located along the pacific coast. Like many other Latin American cities, has significant seismic risk. We implemented the multi-channel analysis of surface waves and the horizontal-to-vertical spectral ratio methods to estimate shear wave velocity and soil resonance frequency. We considered standard penetration test to determine the penetration resistance and soil classification. We also defined building typologies based on construction materials and structural systems. The VS30 parameter shows that Puerto Vallarta has the three poorest soil classifications. The resonance frequency parameter shows four zones with different fundamental soil periods. We inferred the building's vulnerability from the coupling between the structural and soil fundamental period and the soil characteristics. The analysis shows several vulnerable buildings scatters within the city, e.g., within the tourist area, confined masonry buildings from one to five stories and moment resistance frame buildings up to 12 in the tourist area, poorly confined masonry houses of one to two stories, and confined masonry buildings of one to five stories in the residential/commercial. We present an approach that combines the academic and government to solve a real and transcendental problem since it might directly affect the regulation and structure evaluations in the area. We are sure that these exercises are of great interest in urban growth areas in other parts of the world, especially in Latin America, to achieve seismic risk mitigation.


2021 ◽  
Vol 331 ◽  
pp. 07002
Author(s):  
Afnindar Fakhrurrozi ◽  
Anggun Mayang Sari ◽  
Arifan Jaya Syahbana ◽  
Dwi Sarah ◽  
Bambang Setiadi ◽  
...  

An important key to determining the disaster risk is exposure. It is truly dynamic in space and time due to the expansion and change of the settlements. A seismic hazard is an earthquake disaster that can deliver damage to the physical environment. Hence, it is required to analyse the objects exposed by an active earthquake source in the Bandung Basin. The exposed objects that experience the most impact due to the shock of the earthquake are residential buildings. The West Bandung Regency was opted as our study area due to the high-risk zone for earthquake waves based on seismic hazard calculation. This paper tried to analyse the seismic exposure as the impact of earthquake waves around the Bandung Basin on physical buildings in the West Bandung Regency using a geospatial analytics approach. The result shows that the location area with many damaged buildings correlates with the spatial distribution of surface peak ground acceleration.


Author(s):  
D. Al-Dogom ◽  
K. Schuckma ◽  
R. Al-Ruzouq

<p><strong>Abstract.</strong> Assessing and analyzing the spatial distribution of earthquake events aids in identifying the presence of clustering and reveals hot and cold spots across the study area. Combining the spatial analysis of earthquake events with other geographical and geophysical parameters leads to more understanding of the vulnerability of critical infrastructure and the demographics of the affected population. This study will use Geographical Information Systems (GIS) to examine the spatiotemporal occurrence of earthquake events throughout the Arabian plate and their effect on the United Arab Emirates (UAE). Spatial pattern analysis techniques, including Moran I and Getis–Ord Gi*, were applied to 115 years of earthquakes (1900&amp;ndash;2015) that have occurred throughout the Arabian plate. The directional distribution (standard deviational ellipse) of earthquake magnitudes was analyzed to determine the spatial characteristics and the directional tendency of the earthquakes throughout the Arabian plate. Afterword, geophysical parameters of UAE, specifically Peak Ground Acceleration (PGA), fault line distance, slope, soil type, and geology were ranked, weighted based on its contribution and combined using an Analytic Hierarchy Process (AHP) to identify and locate seismic hazard zones. The resulted Seismic Hazard Zonation Map (SHZM) was classified to five hazard zones ranging from very high to very low. It has been found that Fujairah city sited in the “very High” zone, Sharjah and Dubai cities located from “High” to moderate zones while Abu Dhabi city stands relatively far from seismic hot spots and major faults and placed in the low seismic hazard zone. The results of this study could help improve urban planning and emergency mitigation strategies in UAE.</p>


2021 ◽  
pp. 875529302110435
Author(s):  
Wael M Hassan ◽  
Janise Rodgers ◽  
Christopher Motter ◽  
John Thornley

Southcentral Alaska, the most populous region in Alaska, was violently shaken by a Mw 7.1 earthquake on 30 November 2018 at 8:29 am Alaska Standard Time. This was the largest magnitude earthquake in the United States close to a population center in over 50 years. The earthquake was 46 km deep, and the epicenter was 12 km north of Anchorage and 19 km west of Eagle River. The event affected some 400,000 residents, causing widespread damage in highways, nonstructural components, non-engineered and older buildings, and structures on poorly compacted fills. A few isolated serious injuries and partial collapses took place. Minor structural damage to code-conforming buildings was observed. A significant percentage of the structural damage was due to geotechnical failures. Building stock diversity allows use of the region as a large test bed to observe how local building practices affected earthquake damage levels. The prevailing peak ground acceleration (PGA) was 0.2–0.32 g, causing shaking intensity at most sites of 50%–60% of the ASCE 7-16 design basis earthquake acceleration. Thus, the seismic vulnerability of building stock in the region was not truly tested. Reinforced concrete buildings had minor structural damage, except in a few cases of shear wall and transfer girder shear cracking. Fiber-reinforced polymer (FRP)-retrofitted buildings performed satisfactorily. Concrete-masonry-unit (CMU) masonry buildings experienced serious structural damage in many cases, including relatively newer buildings. The earthquake caused widespread structural damage in non-engineered buildings (primarily wood and CMU masonry) that exist widely in the region, especially in Eagle River. Of these, non-engineered single-family wood buildings had the heaviest structural damage. No structural damage could be observed in steel buildings. The aftershock sequence, which included 7 M5+ and 50 M4+ events, exacerbated structural damage in all types of buildings. The present study is based on the EERI field reconnaissance mission conducted by the authors following the earthquake. Based on the observed damage and structural performance, seismic risk mitigation recommendations are suggested.


Author(s):  
Fabio Petruzzelli ◽  
Iunio Iervolino

AbstractPrioritization of seismic risk mitigation at a large scale requires rough-input methodologies able to provide an expedited, yet conventional, assessment of the seismic risk corresponding to the portfolio of interest. In fact, an evaluation of seismic vulnerability at regional level by means of mechanics-based methods is generally only feasible for a fraction of the portfolio, selected according to prioritization criteria, due to the sheer volume of information and computational effort required. Therefore, conventional assessment of seismic risk via simple indices has been proposed in literature and in some guidelines, mainly based on the comparison of code requirements at the time of design and current seismic demand. These indices represent an attempt to define a relative seismic risk measure for a rapid ranking to identify the part of the portfolio that deserves further investigation. Although these risk metrics are based on strong assumptions, they have the advantage of only requiring easy-to-retrieve data, such as design year and location as the bare minimum, making them suitable for applications within the risk analysis industry. Moreover, they can take both hazard and vulnerability into account, albeit conventionally, and can be manipulated in order to account for exposure in terms of individual or societal risks. In the present study, the main assumptions, limitations, and possible evolutions of existing prioritization approaches to nominal risk are reviewed, with specific reference to the Italian case. Furthermore, this article presents the software NODE (available to interested readers), which enables the computation of location-specific code-based seismic performance demands, according to the Italian code and the evolution of seismic classification since 1909. Finally, this study intends to contribute to the ongoing debate on strategies for large-scale seismic assessment for building stock management purposes.


2019 ◽  
Vol 109 (6) ◽  
pp. 2644-2657 ◽  
Author(s):  
Mohamad Ridwan ◽  
Phil R. Cummins ◽  
Sri Widiyantoro ◽  
Masyhur Irsyam

Abstract Site characterization is one of the most important components in seismic hazard analysis because it accounts for the important effects of near‐surface geology on ground motion. It is usually quantified based on the time‐averaged S‐wave velocity (VS) for the top 30 m of the profile (VS30). In this study, we estimate the site class in Jakarta based on VS structure estimated using microtremor array observations. The results show that microtremor‐derived VS profiles agree well with standard penetration test‐derived profiles at nine sites. The site‐class estimates in the Jakarta area can be divided into two National Earthquake Hazards Reduction Program classes: (a) site class E (soft soil) located in alluvium, beach ridge, and alluvial fan deposits in northern and western Jakarta, and (b) site class D (stiff soil) found mainly in alluvial fan deposits in southeastern Jakarta. The variation of VS30 in Jakarta leads to different soil amplification factors that will impact the seismic hazard at the surface. We show that the seismic hazard resulting from selected ground‐motion models (GMMs) illustrates a clear influence of site effects at long periods (>1  s). However, the effect on peak ground acceleration and response spectra for short periods (0.2 s) appear to be less pronounced, due to the GMMs’ treatment of basin effects and nonlinear soil behavior. Available GMMs may not accurately account for such effects in the Jakarta basin, and GMMs specific to Indonesia should be developed to accurately assess seismic hazard there.


2019 ◽  
Vol 55 (1) ◽  
pp. 109 ◽  
Author(s):  
Nikolaos Vavlas ◽  
Anastasia Kiratzi ◽  
Basil Margaris ◽  
George Karakaisis

We carry out a probabilistic seismic hazard assessment (PSHA) for Lesvos Island, in the northeastern Aegean Sea. Being the most populated island in the northern Aegean Sea and hosting the capital of the prefecture, its seismic potential has significant social-economic meaning. For the seismic hazard estimation, the newest version of the R-CRISIS module, which has high efficiency and flexibility in model selection, is used. We incorporate into the calculations eight (8) ground motion prediction equations (GMPEs). The measures used are peak ground acceleration, (PGA), peak ground velocity, (PGV), and spectral acceleration, (SA), at T=0.2 sec representative of the building stock. We calculate hazard curves for selected sites on the island, sampling the southern and northern parts: Mytilene, the capital, the village of Vrisa, Mithymna and Sigri. Hazard maps are also presented in terms of all three intensity measures, for a mean return period of 475 years (or 10% probability of exceedance in 50 years), assuming a Poisson process. Our results are comparable to the predictions of on-going EU hazard models, but higher than the provisions of the Greek Seismic Code. Finally, we perform disaggregation of hazard to depict the relative contribution of different earthquake sources and magnitudes to the results.


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