Assessment of seismic risk scenarios for Bucharest,Romania

In this paper, seismic risk scenarios for Bucharest, the capital city of Romania, are proposed and assessed. Bucharest has one of the highest seismic risk levels in Europe, and this is due to a combination of relatively high seismic hazard and a building stock built mainly before the devastating Vrancea 1977 earthquake. In this study, the seismic risk of Bucharest is assessed using the most recent information regarding the characteristics of the residential building stock. The ground motion amplitudes are evaluated starting from random fields obtained by coupling a ground motion model derived for the Vrancea intermediate-depth seismic source with a spatial correlation model. The seismic risk evaluation method applied in this study is based on the well-known macroseismic method. For several structural typologies, the vulnerability parameters are evaluated based on a damage survey performed on 18,000 buildings in Bucharest after the March 1977 earthquake. Subsequently, the risk metrics are compared with those from other studies in the literature that apply a different risk assessment methodology in order to gain a better view of the uncertainties associated with a seismic risk study at city level. Finally, the impact of several Vrancea intermediate-depth earthquake scenarios is evaluated and the results show that the earthquake which has the closest epicenter to Bucharest appears to be the most damaging.

     

Assessment of seismic risk scenarios for Bucharest,Romania

In this paper, seismic risk scenarios for Bucharest, the capital city of Romania, are proposed and assessed. Bucharest has one of the highest seismic risk levels in Europe, and this is due to a combination of relatively high seismic hazard and a building stock built mainly before the devastating Vrancea 1977 earthquake. In this study, the seismic risk of Bucharest is assessed using the most recent information regarding the characteristics of the residential building stock. The ground motion amplitudes are evaluated starting from random fields obtained by coupling a ground motion model derived for the Vrancea intermediate-depth seismic source with a spatial correlation model. The seismic risk evaluation method applied in this study is based on the well-known macroseismic method. For several structural typologies, the vulnerability parameters are evaluated based on a damage survey performed on 18,000 buildings in Bucharest after the March 1977 earthquake. Subsequently, the risk metrics are compared with those from other studies in the literature that apply a different risk assessment methodology in order to gain a better view of the uncertainties associated with a seismic risk study at city level. Finally, the impact of several Vrancea intermediate-depth earthquake scenarios is evaluated and the results show that the earthquake which has the closest epicenter to Bucharest appears to be the most damaging.     

Social vulnerability and seismic risk perception. Case study: the historic center of the Bucharest Municipality/Romania

Social vulnerability is as much a part of risk as building damage, hazard magnitude, and economic loss. Social vulnerability refers to the capacity of a human community exposed during the impact of a natural hazard event (in this case, an earthquake) to resist, cope with, and recover from that impact. In the perspective of the 3rd millennium, we come to understand that the most efficient and accessible way to reduce the pressure of natural risks is to reduce the vulnerability level of the human communities exposed to that certain hazard. This study aims to test, in an exposed and vulnerable area, the relationship between social vulnerability and the perception of the seismic risk. The research focuses only on the first level of social vulnerability, defined as the ability of an individual within a household to recover from a natural hazard impact (Dwyer et al. 2004). A prevailing assumption was that social vulnerability influences the level of perception of the seismic risk, in an exposed, vulnerable area. To this end, two samples were used, different under the aspect of social vulnerability, in the context of the same residential area. Social vulnerability was computed as a normalized composed index that includes the poverty ratio and the demographic vulnerability ratio (depending on the age, gender, and education level indicators). The statistical processing has indicated a significant difference in the high perception level for the two samples that were compared, in the sense that in the context of an increased level of social vulnerability, people generally better acknowledge the seismic risk.

Pathways to seismic hazard evaluation: Extreme and characteristic earthquakes in areas of low and high seismicity

The general philosophy of seismic hazard evaluation described here is appropriate for selection of seismic input to regional earthquake engineering codes prior to detailed on-site inspections and geotechnical assessments. Some probabilistic seismic hazard methodologies which can be applied in areas of low and high seismicity, are briefly described to emphasise the main equations with specimen results. Three aspects of hazard assessment are explored by different pathways. These include the analysis of regional earthquake catalogues to obtain magnitude recurrence, particularly using Gumbel extreme value statistics. This is extended to assess ground shaking hazard which is usually sought by earthquake engineers. Thirdly, the concept of earthquake perceptibility is developed, leading to the identification of an earthquake magnitude or type which is characteristic of a region. This most perceptible earthquake is most likely to be felt at any site in a region and provides an earthquake selection criterion which can be used in aseismic design of noncritical structures. Because there are several methods of seismic hazard evaluation, the view is expressed that it is sensible for practical purposes to seek results from different methods or different pathways to the hazard evaluation.Paper presented at the Commission of the European Communities' School on Earthquake Hazard Evaluation, Athens, and at the 21st General Assembly of the European Seismological Commission, held in Sofia, 1988.Now at School of Environmental Sciences, University of East Anglia, University Plain, Norwich NR4 7TJ, U.K.     

A quantitative appraisal of earthquake hazard parameters computed from Gumbel I method for different regions in and around Turkey

Useful information concerning the earthquake hazard parameters distributed in Turkey and the adjacent areas are estimated in the present work. Based on Gumbel’s I distribution parameters we are able to estimate the hazard values of the investigated area which are the mean return periods, the most probable maximum magnitude in the time period of t-years and the probability for an earthquake occurrence of magnitude ≥M during a time span of t-years. Figures concerning the spatial distribution of probabilities and the return periods are plotted and we considered them of particular interest for mapping the earthquake hazard in Turkey and the surrounding areas. These figures effectively produce a brief earthquake hazard atlas. The quantitative appraisal of the hazard parameters is useful for engineers, planners, etc., because it provides a tool for earthquake resistant design.     

A seismic landslide hazard analysis with topographic effect,a case study in the 99 Peaks region,Central Taiwan

It has been known that ground motion amplitude will be amplified at mountaintops; however, such topographic effects are not included in conventional landslide hazard models. In this study, a modified procedure that considers the topographic effects is proposed to analyze the seismic landslide hazard. The topographic effect is estimated by back analysis. First, a 3D dynamic numerical model with irregular topography is constructed. The theoretical topographic amplification factors are derived from the dynamic numerical model. The ground motion record is regarded as the reference motion in the plane area. By combining the topographic amplification factors with the reference motions, the amplified acceleration time history and amplified seismic intensity parameters are obtained. Newmark’s displacement model is chosen to perform the seismic landslide hazard analysis. By combining the regression equation and the seismic parameter of peak ground acceleration and Arias intensity, the Newmark’s displacement distribution is generated. Subsequently, the calculated Newmark’s displacement maps are transformed to the hazard maps. The landslide hazard maps of the 99 Peaks region, Central Taiwan are evaluated. The actual landslide inventory maps triggered by the 21 September 1999, Chi-Chi earthquake are compared with the calculated hazard maps. Relative to the conventional procedure, the results show that the proposed procedures, which include the topographic effect can obtain a better result for seismic landslide hazard analysis. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

First Order Seismic Microzonation of Delhi,India Using Geographic Information System (GIS)

A first order seismic microzonation map of Delhi is prepared using five thematic layers viz., Peak Ground Acceleration (PGA) contour, different soil types at 6 m depth, geology, groundwater fluctuation and bedrock depth, integrated on GIS platform. The integration is performed following a pair-wise comparison of Analytical Hierarchy Process (AHP), wherein each thematic map is assigned weight in the 5-1 scale: depending on its contribution towards the seismic hazard. Following the AHP, the weightage assigned to each theme are: PGA (0.333), soil (0.266), geology (0.20), groundwater (0.133) and bedrock depth (0.066). The thematic vector layers are overlaid and integrated using GIS. On the microzonation theme, the Delhi region has been classified into four broad zones of vulnerability to the seismic hazard. They are very high (> 52%), high (38–52%), moderate (23–38%) and less ( < 23%) zones of seismic hazard. The “very high” seismic hazard zone is observed where the maximum PGA varies from 140 to 210 gal for a finite source model of M_w 8.5 in the central seismic gap. A site amplification study from local and regional earthquakes for Delhi region using Delhi Telemetry Network data shows a steeper site response gradient in the eastern side of the Yamuna fluvial deposits at 1.5 Hz. The ‘high’ seismic hazard zone occupies most of the study area where the PGA value ranges from 90 to 140 gal. The ‘moderate’ seismic hazard zone occurs on either side of the Delhi ridge with PGA value varying from 60 to 90 gal. The ‘less’ seismic hazard zone occurs in small patches distributed along the study area with the PGA value less than 60 gal. Site response studies, PGA distribution and destruction pattern of the Chamoli earthquake greatly corroborate the seismic hazard zones estimated through microzonation on GIS platform and also establishes the methodology incorporated in this study.     

Probabilistic seismic hazard of Pakistan, Azad-Jammu and Kashmir

The seismic hazard study for Pakistan and Azad Jammu and Kashmir has been conducted by using probabilistic approach in terms of peak ground acceleration (PGA) in m/s² and also seismic hazard response spectra for different cities. A new version of Ambraseys et al. (Bull Earthq Eng 3:1–53, 2005) ground acceleration model is used, and parameterization is based on most recent updated earthquake catalogs that consisted of 14,000 events. The threshold magnitude was fixed at M _w 4.8, but seismic zones like northern Pakistan–Tajikistan, Hindukush and northern Afghanistan–Tajikistan border had M _w 5.2. The average normalized ‘a’ and ‘b’ values for all zones are 6.15 and 0.95, respectively. Seismicity of study area was modeled, and ground motion was computed for eight frequencies (0.025, 0.1, 0.2, 0.5, 1.0, 1.5, 2.0, 2.5 s) for different annual exceedance rates of 0.02, 0.01, 0.005, 0.002 and 0.001 (return periods 50, 100, 200, 500 and 1,000 years) for stiff rocks at the gridding of 0.1° × 0.1°. Seismic hazard maps based on computed PGA for 0.02, 0.01 and 0.002 annual exceedance are prepared. These maps indicate the earthquake hazard of Pakistan and surrounding areas in the form of acceleration contour lines, which are in agreement with geological and seismotectonic characteristics of the study area. The maximum seismic hazard values are found at Muzaffarabad, Gilgit and Quetta areas.     

Benford’s Law in Time Series Analysis of Seismic Clusters

Benford’s analysis is applied to the recurrence times of approximately 17,000 seismic events in different geological contexts of Italy over the last 6 years, including the Mt. Etna volcanic area and the seismic series associated with the destructive M _w 6.3, 2009 L’Aquila earthquake. A close conformity to Benford’s law and a power-law probability distribution for the recurrence times of consecutive events is found, as typical of random multiplicative processes. The application of Benford’s law to the recurrence event times in seismic series of specific seismogenic regions represents a novel approach, which enlarges the occurrence and relevance of Benford-like asymmetries, with implications on the physics of natural systems approaching a power law behaviour. Moreover, we propose that the shift from a close conformity of Benford’s law to Brownian dynamics, observed for time separations among non-consecutive events in the study seismic series, may be ruled by a periodical noise factor, such as the effects of Earth tides on seismicity tuning.     

Influence of slow active faults in probabilistic seismic hazard assessment: the northwestern margin of the València trough

Areas of low strain rate are typically characterized by low to moderate seismicity. The earthquake catalogs for these regions do not usually include large earthquakes because of their long recurrence periods. In cases where the recurrence period of large earthquakes is much longer than the catalog time span, probabilistic seismic hazard is underestimated. The information provided by geological and paleo-seismological studies can potentially improve seismic hazard estimation through renewal models, which assume characteristic earthquakes. In this work, we compare the differences produced when active faults in the northwestern margin of the València trough are introduced in hazard analysis. The differences between the models demonstrate that the introduction of faults in zones characterized by low seismic activity can give rise to significant changes in the hazard values and location. The earthquake and fault seismic parameters (recurrence interval, segmentation or fault length that controls the maximum magnitude earthquake and time elapsed since the last event or T_e) were studied to ascertain their effect on the final hazard results. The most critical parameter is the recurrence interval, where shorter recurrences produce higher hazard values. The next most important parameter is the fault segmentation. Higher hazard values are obtained when the fault has segments capable of producing big earthquakes. Finally, the least critical parameter is the time elapsed since the last event (T_e), when longer T_e produces higher hazard values.     

Probabilistic seismic hazard analysis for Bangalore

This article presents the results of probabilistic seismic hazard analysis (PSHA) for Bangalore, South India. Analyses have been carried out considering the seismotectonic parameters of the region covering a radius of 350 km keeping Bangalore as the center. Seismic hazard parameter ‘b’ has been evaluated considering the available earthquake data using (1) Gutenberg–Richter (G–R) relationship and (2) Kijko and Sellevoll (1989, 1992) method utilizing extreme and complete catalogs. The ‘b’ parameter was estimated to be 0.62 to 0.98 from G–R relation and 0.87 ± 0.03 from Kijko and Sellevoll method. The results obtained are a little higher than the ‘b’ values published earlier for southern India. Further, probabilistic seismic hazard analysis for Bangalore region has been carried out considering six seismogenic sources. From the analysis, mean annual rate of exceedance and cumulative probability hazard curve for peak ground acceleration (PGA) and spectral acceleration (Sa) have been generated. The quantified hazard values in terms of the rock level peak ground acceleration (PGA) are mapped for 10% probability of exceedance in 50 years on a grid size of 0.5 km × 0.5 km. In addition, Uniform Hazard Response Spectrum (UHRS) at rock level is also developed for the 5% damping corresponding to 10% probability of exceedance in 50 years. The peak ground acceleration (PGA) value of 0.121 g obtained from the present investigation is slightly lower (but comparable) than the PGA values obtained from the deterministic seismic hazard analysis (DSHA) for the same area. However, the PGA value obtained in the current investigation is higher than PGA values reported in the global seismic hazard assessment program (GSHAP) maps of Bhatia et al. (1999) for the shield area.     

Local seismic hazard assessment in areas of weak to moderate seismicity—case study from Eastern Germany

Generally the seismic hazard of an area of interest is considered independent of time. However, its seismic risk or vulnerability, respectively, increases with the population and developing state of economy of the area. Therefore, many areas of moderate seismic hazard gain increasing importance with respect to seismic hazard and risk analysis. However, these areas mostly have a weak earthquake database, i.e., they are characterised by relative low seismicity and uncertain information concerning historical earthquakes. In a case study for Eastern Thuringia (Germany), acting as example for similar places in the world, seismic hazard is estimated using the probabilistic approach. Because of the lack of earthquakes occurring in the recent past, mainly historical earthquakes have to be used. But for these the actual earthquake sources or active faults, needed for the analysis, are imprecisely known. Therefore, the earthquake locations are represented by areal sources, a common practice. The definition of these sources is performed carefully, because their geometrical shape and size (apart from the earthquake occurrence model) influence the results significantly. Using analysis tools such as density maps of earthquake epicentres, seismic strain and energy release support this. Oversizing of areal sources leads to underestimation of seismic hazard and should therefore be avoided. Large location errors of historical earthquakes on the other hand are represented by several alternative areal sources with final superimposition of the different results. In a very similar way information known from macroseismic observations interpreted as source rather than as site effects are taken into account in order to achieve a seismic hazard assessment as realistic as possible. In very local cases the meaning of source effects exceeds those of site effects very likely. The influence of attenuation parameter variations on the result of estimated local seismic hazard is relatively low. Generally, the results obtained by the seismic hazard assessment coincide well with macroseismic observations from the thoroughly investigated largest earthquake in the region.     

Seismic hazard analysis of Lucknow considering local and active seismic gaps

The Himalayas are one of very active seismic regions in the world where devastating earthquakes of 1803 Bihar–Nepal, 1897 Shillong, 1905 Kangra, 1934 Bihar–Nepal, 1950 Assam and 2011 Sikkim were reported. Several researchers highlighted central seismic gap based on the stress accumulation in central part of Himalaya and the non-occurrence of earthquake between 1905 Kangra and 1934 Bihar–Nepal. The region has potential of producing great seismic event in the near future. As a result of this seismic gap, all regions which fall adjacent to the active Himalayan region are under high possible seismic hazard due to future earthquakes in the Himalayan region. In this study, the study area of the Lucknow urban centre which lies within 350 km from the central seismic gap has been considered for detailed assessment of seismic hazard. The city of Lucknow also lies close to Lucknow–Faizabad fault having a seismic gap of 350 years. Considering the possible seismic gap in the Himalayan region and also the seismic gap in Lucknow–Faizabad fault, the seismic hazard of Lucknow has been studied based on deterministic and the probabilistic seismic hazard analysis. Results obtained show that the northern and western parts of Lucknow are found to have a peak ground acceleration of 0.11–0.13 g, which is 1.6- to 2.0-fold higher than the seismic hazard compared to the other parts of Lucknow.     

Earthquake disaster risk assessment and evaluation for Turkey

Turkey is the one country in which 90% of the buildings are subject to the risk of earthquake disaster. Recent earthquakes revealed that Turkey’s present residential reinforced-concrete constructions are insufficient in earthquake resistance. Many of the buildings which collapsed or were severely damaged have been rehabilitated by applying simple methods, whose adequacy is questionable. As in Japan and the United States, Turkey’s earthquake assessment studies have increased, especially after earthquakes in 1999, In US, several methodologies and standards, such as Hazard-US (HAZUS) and Applied Technology Council (ATC) 13-20-21 and 156, provide comprehensive earthquake loss estimation methodology for post-earthquake assessment. This paper provides post-earthquake assessment and disaster management for Turkey. The main aim of the post-earthquake assessment discussed is to evaluate loss and estimate damage through disaster management approach. Classification criteria for damage are essential to determine the situation after an earthquake in both the short and long terms. The methodology includes probabilistic-based analysis, which considers the magnitude of Ms ≥ 5.0 earthquakes between 1900 and 2005, for determining the probabilistic seismic hazard for Turkey.     

Systematization of active faults for the assessment of the seismic hazard

A systematization of active faults has been developed based on the progress of scientists from the leading countries in the world in the study of seismotectonics and seismic hazard problems. It is underlain by the concept of the fault-block structure of the geological-geophysical environment governed by the interaction of differently oriented active faults, which are divided into two groups—seismogenic and nonseismogenic faults. In seismogenic fault zones, the tectonic stress accumulated is relieved by means of strong earthquakes. Nonseismogenic fault zones are characterized by creep displacement or short-term, oscillatory, and reciprocal movements, which are referred to local superintense deformations of the Earth’s crust (according to the terminology used by Yu.O. Kuz’min). For a situation when a strong earthquake happens, a subgroup of seismodistributing faults has been identified that surround the seismic source and affect the distribution of the seismic waves and, as a consequence, the pattern of the propagation of the coseismic deformations in the fault-block environment. Seismodistributing faults are divided into transit and sealing faults. Along transit faults, secondary coseismic effects (landfalls, landslides, ground fractures, liquefaction, etc) are intensified during earthquakes. In the case of sealing faults, enhancement of the coseismic effects can be observed on the disjunctive limb nearest to the epicenter, whereas, on the opposite limb, the intensity of such effects appreciably decreases. Seismogenic faults or their systems are associated with zones of earthquake source origination (ESO), which include concentrated seismicity regions. In such zones, each earthquake source is related to the evolution of a fault system. ESO zones also contain individual seismogenic sources being focuses of strong earthquakes with M of ≥5.5 in the form of ruptures, which can be graphically represented in 2D or 3D as a surface projection of the source. Depending on the type of data based on which they are identified, individual seismogenic sources are divided into geological-geophysical and macroseismic sources. The systematization presented is the theoretical basis for and the concept of the relational database that is being developed by the authors as an information system for the generation of seismotectonic GIS projects required for the subsequent analysis of the seismic hazard and the assessment of the probability of the origination of macroseismic earthquake effects in a predetermined location.     

Site-specific earthquake response study for hazard assessment in Kolkata city,India

The assessment of local site effects on seismic ground motions is of great importance in earthquake engineering practice. Several destructive earthquakes in the past have demonstrated that the amplification of ground motion and associated damage to structures due to local site conditions is a significant consideration in earthquake hazard analysis. A recent paper published in this journal highlights the hazard posed by earthquakes in the megacity of Kolkata in India due to its seismic and geological settings. The seismic hazard assessment study speculates that the deep alluvial deposit in the city may increase the seismic hazard probably due to the amplification of the seismic energies. This paper focuses on the seismic response studies of the various soil strata (i.e. for local subsurface conditions) obtained from various construction sites in the city for predicted earthquake. It is very well recognized that site response studies (a part of seismic microhazard zonation for urban areas) are the first step towards performance-based foundation design or seismic risk analysis and mitigation strategy. One of the problems for carrying out site-specific study in Kolkata is the lack of recorded strong motion data in the city. Hence, this paper outlines a methodology to carry out site-specific study, where no strong motion data or seismic data are available. The methodology uses wavelet-based spectrum compatibility approach to generate synthetic earthquake motions and equivalent linear method for seismic site response analysis. The Mega City of Kolkata has been considered to explain the methodology. Seismic hazard zonation map by the Bureau of Indian Standards classifies the City of Kolkata as moderate seismic zone (Zone III) with a zone factor 0.16. On the other hand, GSHAP(Global Seismic Hazard Assessment Program) map which is based on 10% probability of exceedance in 50 years specifies a maximum peak ground acceleration (PGA) of 1.6 m/s² (0.163 g) for this region. In the present study, the seismic response has been carried out based on GSHAP. The results of the analysis indicate the amplification of ground motion in the range of 4.46–4.82 with the fundamental period ranging from 0.81 to 1.17 s. Furthermore, the maximum spectral accelerations vary in the range of 0.78–0.95 g.     

白龙江引水工程代古寺水库及其周围地区地震危险性评估

白龙江引水工程是我国拟建的一项重大战略工程,而代古寺水库是该工程的水源枢纽。代古寺水库及其周围地区(本文研究区)活动断层发育、大地震频发,故亟需开展可靠的地震危险性评估,为该研究区内的工程建设和运营保驾护航。由于传统评估方法物理依据不足,难以正确评估研究区的地震危险性,故本文采用了基于地震物理预测的地震危险性评估新方法。研究结果表明,该研究区位于海原地震区,未来100年内该研究区的地震危险性主要源于海原地震区的下一次M_S8.5标志性地震。根据断层地震活动、发震潜力与展布特征,我们预判了该标志性地震的可能发震断层和震中位置;应用地震烈度衰减关系,考虑不同震中位置,分别计算了其产生的地震烈度。为确保“百年大计”的白龙江引水工程代古寺水库水资源枢纽安全,我们建议该研究区的抗震设防烈度不宜低于8度。     

Estimation of seismic hazard parameters in TERESA test areas

A general overview of some of the problems involved in earthquake catalogue handling is given as part of the works carried out into the ESC/SC8-TERESA project related with the seismic hazard assessment in two selected test areas: Sannio-Matese in Italy and the northern Rhine region (BGN). Furthermore, the necessary input data to be used in the calculation of seismic hazard has been obtained, including earthquake source zones and their seismic hazard parameters.The importance is pointed out of detailed analysis of seismic catalogues, mainly in relation to the use of aftershock information, the historical records of the region, and the possible temporal and spatial variation of seismicity, which could have an important influence on short-term hazard assessment.     

Seismotectonic features of the September 24, 1999 Ahram earthquake in the Zagros,Iran

The September 24, 1999 Ahram Earthquake in southwestern Iran was moderate in energy (M = 5.0–5.5 from different sources) and did not entail significant destruction and casualities. The tectonic position of the source zone, surficial seismic dislocations, and results of macroseismic and seismological study of this seismic event in the junction zone of the Zagros Fold System and the piedmont plain are described in the paper, including data on rejuvenated ancient ruptures exposed in two trenches excavated across the strike of the regional Kazerun-Borazjan Fault. One of the trenches was driven a few months before and the other a year after this seismic event. The conclusion is drawn that new deformations in the Quaternary near-surface sediments observed at the walls of both trenches may be regarded as unusual seismic ruptures of the Ahram earthquake. These ruptures, described as proved primary seismic dislocations of such a moderate seismic event, are a unique phenomenon in the world seismotectonic practice. The localization of the earthquake source zone in the Kazerun-Borazjan Fault Zone with complex kinematics makes it possible to study the internal structure of one of the most important tectonic lines of the Zagros Fold Region.     

A procedure to estimate the seismic hazard in an urban area: an application to Acireale (Eastern Sicily)

A “standard procedure” to characterize the seismic hazard of a given area was proposed. It is based on a multidisciplinary approach implying: (1) the knowledge of the seismic history of the area; (2) detailed geological surveys; (3)seismic noise measurements; (4) simulations of earthquake scenarios. The downtown of Acireale, a typical baroque town located on Eastern Sicily, was chosen as the “test area”. A catalog of the local seismogenic faults (able to generate earthquakes in historical times) has been compiled, as well as a seismic catalog for the effects of both local and regional earthquakes. The analysis of both catalogs allowed us to make the following conclusions: (1) the most important seismogenic faults affecting the Acireale municipality do not affect the downtown, while the related local earthquakes attenuate their energy (and intensity) in short (few km) distances; (2) the highest seismic intensity (degree X) experienced in Acireale downtown was caused by the 1693 regional earthquake; (3) over the last 140 years, the downtown has experienced the highest intensity value of VII only once, while six times the intensity was VI. On the whole, this implies a moderate seismic hazard. The estimation of the seismic hazard has been also approached by the experimental method of recording seismic noise. Measurements have been performed at seven different sites, where drills gave detailed information on the shallow subsurface geology to obtain HV (horizontal/vertical) spectral ratios. On the whole, the highest site amplification factor was moderate (about 7). A further investigation based on synthetic seismograms (and spectra) produced by simulating two given earthquake scenarios was also performed. The two scenarios are, respectively, representative of the largest expected earthquake in the area (the 1693 shock) and of a moderate (magnitude ca. 5.5) local earthquake (as the 1818 one). Moderate to strong locally expected accelerations were evidenced.