Journal articles on the topic 'Macroseismic intensities'
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Vannucci, Gianfranco, Barbara Lolli, and Paolo Gasperini. "Inhomogeneity of Macroseismic Intensities in Italy and Consequences for Macroseismic Magnitude Estimation." Seismological Research Letters 92, no. 4 (March 31, 2021): 2234–44. http://dx.doi.org/10.1785/0220200273.
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Abstract We show that macroseismic intensities assessed in Italy in the last decade are not homogeneous with those of the previous periods. This is partly related to the recent adoption of the European Macroseismic Scale (EMS) in place of the Mercalli–Cancani–Sieberg (MCS) scale used up to about one decade ago. The underestimation of EMS with respect to MCS is about a half of a degree on average and, even more significant, if the MCS intensities are estimated according to the approach developed for the quick evaluations of damage by macroseismic seismologists of the Italian Department of Civil Protection. We also show the inhomogeneity over time of the average differences between instrumental and macroseismic magnitudes computed from intensity data, indicating an average overestimation of magnitudes of about 0.3 units for the instrumental ones before year 1960 and of about 0.2 units for the macroseismic ones after such date. This is consistent with previous studies that hypothesized the incorrect calibration of mechanical recording seismometers operating in Italy and in the surrounding countries before the introduction of the standard electromagnetic seismometers from the beginning of 1960s. For such reasons, the magnitudes of preinstrumental earthquakes in the Catalogo Parametrico dei Terremoti Italiani seismic catalog, used for the most recent seismic hazard assessment in Italy, might be overestimated, on average, by about 0.1–0.2 magnitude units.
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Cajamarca-Zuniga, David, Oleg Vasil'evich Kabantsev, and Christopher Marin. "Macroseismic intensity-based catalogue of earthquakes in Ecuador." Structural Mechanics of Engineering Constructions and Buildings 18, no. 2 (July 20, 2022): 161–71. http://dx.doi.org/10.22363/1815-5235-2022-18-2-161-171.
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Earthquake magnitude catalogues and peak ground acceleration (PGA) maps for Ecuador may be found in several studies, however, there are rare works on the characterisation of the epicentral macroseismic intensities associated with earthquakes. In view of the concept that macroseismic intensity enables us to categorise the extent and severity of damage to buildings and structures caused by an earthquake, this study aims to compile a macro-seismic intensity-based catalogue of earthquakes in Ecuador, characterise the epicentral macroseismic intensities associated to seismogenic sources and perform a comparison with the National Seismic Hazard Map. This paper is the first that presents a catalogue of earthquakes with macroseismic intensities ≥VII and a series of maps of earthquake epicentres according to intensity, focal depth, data and magnitude of seismic events in Ecuador, based on the study of historical and instrumental records from 1900 to 2021. The obtained data shows that 95% of the territory of Ecuador has a PGA 0.1 g, which corresponds to seismic intensities greater than VII, while regions with seismicityVIII (ag = 0.2 g) constitute 86%, and 3.8% of the territory of Ecuador has very high seismicity (IX), where the PGA exceeds 0.5 g. This information suggests that the normative National Seismic Hazard Map of Ecuador underestimate the hazard mainly in the south-east and in the Central Andes of Ecuador, and require an actualization.
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Sbarra, Paola, Patrizia Tosi, Valerio De Rubeis, and Diego Sorrentino. "Quantification of earthquake diagnostic effects to assess low macroseismic intensities." Natural Hazards 104, no. 3 (September 7, 2020): 1957–73. http://dx.doi.org/10.1007/s11069-020-04256-6.
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Abstract A large amount of data about earthquake effects, supplied by citizens through a web-based questionnaire, enabled the analysis of the occurrence of many of the effects on humans and objects listed in macroseismic scales descriptions. Regarding the other diagnostic effects (rattling, moving, shifting, falling or overturning depending of the object type of doors, windows, china, glasses, small objects, pictures, vases, books, as well as frightened people and animal behaviour), data from more than 300,000 questionnaires about earthquakes felt in Italy from June 2007 to August 2017, were analysed by stacking them together as a function of hypocentral distance and magnitude. The comparison of the resulting percentages with the intensity prediction equation showed that almost all the chosen effects are good diagnostics for macroseismic intensity evaluation, as their percentages are well differentiated. We did not analyse the oscillations of hanging objects and liquids because the differences in effect attenuations, highlighted by the maps of the occurrence percentage, suggested to not consider them as diagnostic effect. This result allowed us to quantify the occurrence of each diagnostic effect for the intensity degrees from II to VI of the European macroseismic scale for the people who felt the earthquake. The application of the intensity assessment method to internet macroseismic data, based on the specifications herein proposed, should mitigate the problem of “not felt” undersampling in crowdsourced web data.
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Stromeyer, D., and G. Grunthal. "Attenuation Relationship of Macroseismic Intensities in Central Europe." Bulletin of the Seismological Society of America 99, no. 2A (April 1, 2009): 554–65. http://dx.doi.org/10.1785/0120080011.
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Adhikari, Sujan Raj, Gopi Baysal, Amod Dixit, Stacey S. Martin, Mattieu Landes, Remy Bossu, and Susan E. Hough. "Toward a Unified Near-Field Intensity Map of the 2015 Mw 7.8 Gorkha, Nepal, Earthquake." Earthquake Spectra 33, no. 1_suppl (December 2017): 21–34. http://dx.doi.org/10.1193/120716eqs226m.
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We develop a unified near-field shaking intensity map for the 25 April 2015 Mw 7.8 Gorkha, Nepal, earthquake by synthesizing intensities derived from macroseismic effects that were determined by independent groups using a variety of approaches. Independent assessments by different groups are generally consistent, with minor differences that are likely due in large part to differences in spatial sampling. Throughout most of the near-field region, European Macroseismic Scale (EMS-98) intensities were generally close to 7 EMS. In the Kathmandu Valley, intensities were somewhat higher (6.5–7.5) along the periphery of the valley and in the adjacent foothills than in the central valley, where they were ≈6. The results are consistent with instrumental intensity values estimated from available data using a published relationship between peak ground acceleration (PGA) and intensity. Using this relationship to convert intensities to PGA, we estimate strong-motion PGA de-amplification factors of ≈0.7 in the central Kathmandu Valley, with amplification of ≈1.6 in adjacent foothills. The results support the conclusion that the Kathmandu Valley experienced a pervasively nonlinear response during the Gorkha main shock.
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Oliveti, Ilaria, Licia Faenza, and Alberto Michelini. "INGe: Intensity-ground motion data set for Italy." Annals of Geophysics 65, no. 1 (March 24, 2022): DM102. http://dx.doi.org/10.4401/ag-8709.
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In this paper we present an updated and homogeneous earthquake dataset for Italy compiled by joining the intensities available in the Italian Macroseismic Database DBMI15 and the peak ground motion (PGM) parameters present in the Engineering Strong-Motion (ESM) accelerometric data bank. The database has been compiled through an extensive procedure of evaluation and revision based on two main steps: 1) the selection of the earthquakes in DBMI15 with homogeneous macroseismic intensities in terms of data sources and 2) the extraction of all the localities reporting intensity data which are located within 3 km from the accelerograph stations that recorded the data. The final dataset includes 519 intensity-PGM data pairs from 65 earthquakes and 227 stations in the time span 1972–2016. The reported intensities are expressed either in the Mercalli-Cancani- Sieberg (MCS) or the European macroseismic (EMS-98) scales. The events are characterized by magnitudes in the range 4.1–6.8 and depths in the range 0–55 km. Here, we illustrate the data collection and the properties of the database in terms of recording, event and station distributions as well as macroseismic intensity points. Furthermore, we discuss the most relevant features of engineering interest showing several statistics with reference to the most significant metadata (such as moment magnitude, several distance metrics, style of faulting etc). The dataset is expected to be useful for benchmarking existing and for developing new ground motion intensity conversion equations offering a common basis, and sparing the time and effort required for assembling to the interested researchers. The dataset is available at https://zenodo.org/record/4623732#.YNX-AZMzbdc.
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Mäntyniemi, Päivi, Mathilde B. Sørensen, and Ruben E. Tatevossian. "Testing the Environmental Seismic Intensity Scale on Data Derived from the Earthquakes of 1626, 1759, 1819, and 1904 in Fennoscandia, Northern Europe." Geosciences 11, no. 1 (December 29, 2020): 14. http://dx.doi.org/10.3390/geosciences11010014.
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Earthquake environmental effects (EEEs) were compiled for the earthquakes of 1626, 1759, 1819, and 1904 in the Fennoscandian Peninsula, northern Europe. The principal source of information was the contemporary newspaper press. Macroseismic questionnaires collected in 1759 and 1904 were also consulted. We prepared maps showing newly discovered EEEs together with previously known EEEs and analyzed their spatial distribution. We assigned intensities based on the 2007 Environmental Seismic Intensity (ESI) scale to 27 selected localities and compared them to intensities assigned based on the 1998 European Macroseismic Scale. While the overall agreement between the scales is good, intensities may remain uncertain due to the sparsity of written documentation. The collected data sets are most probably incomplete but still show that EEEs are not unprecedented cases in the target region. The findings include landslides and rockfalls as well as cascade effects with a risk potential and widespread water movements up to long distances. The winter earthquake of 1759 cracked ice over a large area. This investigation demonstrates that the ESI scale also has practical importance for regions with infrequent EEEs.
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Gosar, Andrej. "Analysis of the Impact of Fault Mechanism Radiation Patterns on Macroseismic Fields in the Epicentral Area of 1998 and 2004 Krn Mountains Earthquakes (NW Slovenia)." Scientific World Journal 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/206843.
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Two moderate magnitude (Mw = 5.6 and 5.2) earthquakes in Krn Mountains occurred in 1998 and 2004 which had maximum intensity VII-VIII and VI-VII EMS-98, respectively. Comparison of both macroseismic fields showed unexpected differences in the epicentral area which cannot be explained by site effects. Considerably, different distribution of the highest intensities can be noticed with respect to the strike of the seismogenic fault and in some localities even higher intensities have been estimated for the smaller earthquake. Although hypocentres of both earthquakes were only 2 km apart and were located on the same seismogenic Ravne fault, their focal mechanisms showed a slight difference: almost pure dextral strike-slip for the first event and a strike-slip with small reverse component on a steep fault plane for the second one. Seismotectonically the difference is explained as an active growth of the Ravne fault at its NW end. The radiation patterns of both events were studied to explain their possible impact on the observed variations in macroseismic fields and damage distribution. Radiation amplitude lobes were computed for three orthogonal directions: radial P, SV, and SH. The highest intensities of both earthquakes were systematically observed in directions of four (1998) or two (2004) large amplitude lobes in SH component (which corresponds mainly to Love waves), which have significantly different orientation for both events. On the other hand, radial P direction, which is almost purely symmetrical for the strike-slip mechanism of 1998 event, showed for the 2004 event that its small reverse component of movement has resulted in a very pronounced amplitude lobe in SW direction where two settlements are located which expressed higher intensities in the case of the 2004 event with respect to the 1998 one. Although both macroseismic fields are very complex due to influences of multiple earthquakes, retrofitting activity after 1998, site effects, and sparse distribution of settlements, unusual differences in observed intensities can be explained with different radiation patterns.
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Mäntyniemi, Päivi B. "Revisiting Svenskby, Southeastern Finland: Communications Regarding Low-Magnitude Earthquakes in 1751–1752." Geosciences 12, no. 9 (September 12, 2022): 338. http://dx.doi.org/10.3390/geosciences12090338.
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This investigation examines the contemporary documentation of a sequence of low-magnitude earthquakes at the fringes of the Kingdom of Sweden, today Southeastern Finland, in 1751–1752. A total of 11 pages of original correspondence sent from the target village of Svenskby to the Swedish capital Stockholm are reviewed. Newspaper accounts from Sweden and Russia are included in the analysis, and a timeline of the reporting is constructed. A newly created catalog shows over 30 distinct events between the end of October and December 1751 (Julian calendar). The assignment of macroseismic intensity to the earthquakes is hampered by loud acoustic effects that accompany and/or constitute the observations. Maximum intensities are assessed at IV–V (European Macroseismic Scale 1998), and maximum macroseismic magnitudes in the range of MM1.9–2.4, and were probably observed at short epicentral distances close to the ground surface. Comparisons to macroseismic data related to instrumentally recorded earthquakes in the region support the notion of low magnitudes. The data from 1751 provide an analog to modern macroseismic observations from geothermal stimulation experiments. Such experiments have acted as a spur for considering seismic risk from low-magnitude earthquakes whose consequences have seldom previously been a matter for concern.
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Hough, Susan E., Eric Thompson, Grace A. Parker, Robert W. Graves, Kenneth W. Hudnut, Jason Patton, Timothy Dawson, et al. "Near-Field Ground Motions from the July 2019 Ridgecrest, California, Earthquake Sequence." Seismological Research Letters 91, no. 3 (February 26, 2020): 1542–55. http://dx.doi.org/10.1785/0220190279.
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Abstract The 2019 Ridgecrest, California, earthquake sequence, including an Mw 6.4 event on 4 July and an Mw 7.1 approximately 34 hr later, was recorded by 15 instruments within 55 km nearest-fault distance. To characterize and explore near-field ground motions from the Mw 6.4 foreshock and Mw 7.1 mainshock, we augment these records with available macroseismic information, including conventional intensities and displaced rocks. We conclude that near-field shaking intensities were generally below modified Mercalli intensity 9, with concentrations of locally high values toward the northern and southern termini of the mainshock rupture. We further show that, relative to near-field ground motions at hard-rock sites, instrumental ground motions at alluvial near-field sites for both the Mw 6.4 foreshock and Mw 7.1 mainshock were depleted in energy at frequencies higher than 2–3 Hz, as expected from ground-motion models. Both the macroseismic and instrumental observations suggest that sediments in the Indian Wells Valley experienced a pervasively nonlinear response, which helps explain why shaking intensities and damage in the closest population center, Ridgecrest, were relatively modest given its proximity to the earthquakes.
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Leydecker, G., H. Busche, K. P. Bonjer, T. Schmitt, D. Kaiser, S. Simeonova, D. Solakov, and L. Ardeleanu. "Probabilistic seismic hazard in terms of intensities for Bulgaria and Romania – updated hazard maps." Natural Hazards and Earth System Sciences 8, no. 6 (December 16, 2008): 1431–39. http://dx.doi.org/10.5194/nhess-8-1431-2008.
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Abstract. Since 2007 Bulgaria and Romania are members of the European Union. All member states have to introduce the European earthquake building code EUROCODE 8 (EC 8) in the coming years. Therefore, new seismic hazard maps have to be calculated according to the recommendations in EC 8. Here the authors present a novel approach to compute such hazard maps. We prefer to use the macroseismic intensity as hazard parameter because of two reasons: - The irregular azimuthal attenuation pattern of the Vrancea intermediate depth earthquakes can be advantageously taken into account by using detailed macroseismic maps. - The intensity is directly related to the degree of damage and is the original information in the historical earthquake catalogues. The main base of our probabilistic analysis is the earthquake catalogue for SE-Europe (Shebalin et al., 1998) in combination with national and regional catalogues. Fore- and aftershocks were removed. Seismic source zones inside an area of about 200 km around Romania and Bulgaria were defined based on seismicity, neotectonics and geological development. For each seismic source the intensity-frequency relation was calculated and a maximum possible earthquake as well as a seismogenic depth was estimated. An appropriate attenuation law was assumed. To cope with the irregular isoseismals of the Vrancea intermediate depth earthquakes, a factor Ω was included in the macroseismic attenuation law. Using detailed macroseismic maps of three strong intermediate depth earthquakes, Ω was calculated for each observation. Strong local variations of Ω are avoided by averaging within grid cells of 0.5 degree in longitude and 0.25 degree in latitude. The contributions of all seismic sources, the crustal normal depth source zones and the Vrancea intermediate depth zone, were summed up and the annual probability of exceedance was calculated. The contribution of the Vrancea intermediate depth zone to each grid point was computed with the corresponding representative Ω of this point; a seismogenic depth of 120 km has been assumed. Each final seismic hazard map is a combination of two maps, the one for normal depth source zones and the one for the Vrancea intermediate depth zone. This is illustrated for a recurrence period of 475 years. Additional hazard maps were calculated for different recurrence periods.
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Bossu, Rémy, Oona Scotti, Fabrice Cotton, Marc Cushing, and Agnès Levret. "Determination of geomechanical site effects in France from macroseismic intensities and reliability of macroseismic magnitude of historical events." Tectonophysics 324, no. 1-2 (September 2000): 81–110. http://dx.doi.org/10.1016/s0040-1951(00)00112-8.
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Artikov, T. U., R. S. Ibragimov, T. L. Ibragimova, and M. A. Mirzaev. "Macroseismic intensity attenuation equations for Central Asia earthquakes." IOP Conference Series: Earth and Environmental Science 929, no. 1 (November 1, 2021): 012029. http://dx.doi.org/10.1088/1755-1315/929/1/012029.
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Abstract Based on macroseismic survey data for strong earthquakes in Central Asia, the coefficients of attenuation of seismic intensities with distance in the Blake-Shebalin- and Kovesligethy -type equations were refined. A new generalized dependence of macroseismic intensity attenuation on distance, taking into account the depth of the earthquake hypocentre, were obtained. Relations between the minor and major axes of the ellipse approximating real isoseists depending on the shaking strength, source depth and earthquake magnitude were found. With the example of the territory of eastern Uzbekistan, the influence of the choice of the law of seismic intensity attenuation with distance on the obtained seismic hazard assessments is investigated.
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Catita, C., M. P. Teves-Costa, L. Matias, and J. Batlló. "SPATIAL DISTRIBUTION OF FELT INTENSITIES FOR PORTUGAL EARTHQUAKES." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-3/W8 (August 20, 2019): 87–92. http://dx.doi.org/10.5194/isprs-archives-xlii-3-w8-87-2019.
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<p><strong>Abstract.</strong> Macroseismic intensity is a parameter of the severity of ground movement evaluated in terms of the effects that earthquakes produce on people, buildings and the environment, constituting an extremely important information source for the seismologist and engineer of structures. In recent studies, the authors of this study published a new map of maximum intensities observed for continental Portugal considering all observations of macro-seismic intensity higher than III relative to earthquakes occurred between 1344 and 2015 (Teves-Costa et al., 2019). In each parish and municipality of the continental part of the country, the maximum values of intensity were defined. A map of maximum intensities produced in this way was essentially controlled by earthquakes of greater intensity, the 1909.04.23 (near-field) and 1755.11.01 (far-field) earthquakes. In the present work, a spatial distribution of the earthquakes presents in the database (classified by their nature - near-field or far-field - intensity, and epoch) are analysed. The spatial structure, which allows the detection of spatial dependence or autocorrelation of intensity values is also explored in this work, in order to identify regions with similar macroseismic characteristics. The combination of the map of maximum intensities and the products generated in this work are essential for the authorities as a base of support in the definition of joint adaptation strategies for the various regions of the territory, as well as contribute to a better management of the emergency system in Portugal.</p>
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Antonucci, Andrea, Andrea Rovida, Vera D'Amico, and Dario Albarello. "Integrating macroseismic intensity distributions with a probabilistic approach: an application in Italy." Natural Hazards and Earth System Sciences 21, no. 8 (August 3, 2021): 2299–311. http://dx.doi.org/10.5194/nhess-21-2299-2021.
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Abstract. The geographic distribution of earthquake effects quantified in terms of macroseismic intensities, the so-called macroseismic field, provides basic information for several applications including source characterization of pre-instrumental earthquakes and risk analysis. Macroseismic fields of past earthquakes as inferred from historical documentation may present spatial gaps, due to the incompleteness of the available information. We present a probabilistic approach aimed at integrating incomplete intensity distributions by considering the Bayesian combination of estimates provided by intensity prediction equations (IPEs) and data documented at nearby localities, accounting for the relevant uncertainties and the discrete and ordinal nature of intensity values. The performance of the proposed methodology is tested at 28 Italian localities with long and rich seismic histories and for two well-known strong earthquakes (i.e., 1980 southern Italy and 2009 central Italy events). A possible application of the approach is also illustrated relative to a 16th-century earthquake in the northern Apennines.
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Vannucci, G., P. Gasperini, B. Lolli, and L. Gulia. "Fast characterization of sources of recent Italian earthquakes from macroseismic intensities." Tectonophysics 750 (January 2019): 70–92. http://dx.doi.org/10.1016/j.tecto.2018.11.002.
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Beauducel, François, Sara Bazin, Mendy Bengoubou-Valérius, Marie-Paule Bouin, Alexis Bosson, Christian Anténor-Habazac, Valérie Clouard, and Jean-Bernard de Chabalier. "Empirical model for rapid macroseismic intensities prediction in Guadeloupe and Martinique." Comptes Rendus Geoscience 343, no. 11-12 (November 2011): 717–28. http://dx.doi.org/10.1016/j.crte.2011.09.004.
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Zahradn�k, J. "Simple method for combined studies of macroseismic intensities and focal mechanisms." Pure and Applied Geophysics PAGEOPH 130, no. 1 (1989): 83–97. http://dx.doi.org/10.1007/bf00877738.
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Montalvo‐Arrieta, Juan C., Xyoli Pérez‐Campos, Leonardo Ramirez‐Guzman, Rocío L. Sosa‐Ramírez, Moisés Contreras Ruiz‐Esparza, and Miguel Leonardo‐Suárez. "Macroseismic Intensities from the 19 September 2017 Mw 7.1 Puebla–Morelos Earthquake." Seismological Research Letters 90, no. 6 (October 2, 2019): 2142–53. http://dx.doi.org/10.1785/0220190145.
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ABSTRACT We present an analysis of the information collected by the ¿Sintió un sismo? (SUS) web‐based system. One of the most devastating events in central Mexico in the past 35 yr struck near the Mexican states of Puebla and Morelos on 19 September 2017. At the moment of the event, several programs and projects were in place to monitor and perform quick assessments of the magnitude of the earthquake and the severity of its effects on the population and infrastructure. The SUS platform gathers questionnaires designed in Spanish to estimate macroseismic intensities. The availability of such a system in the dominant language of the country permits a broad reach, only limited by the disparity of the services and internet access. By analyzing residuals of the median attenuation intensity of the event, we confirm previous observations on the site and regional effects in Central Mexico such as the strong influence of the Trans‐Mexican volcanic belt on the ground‐motion amplification. In addition, we obtained correlations between peak parameters and macroseismic intensities that reveal the character of the affected structures’ responses. We emphasize the potential usability of systems similar to the SUS at the regional level and their impact on the decision‐making process and support for further research using all available datasets.
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Ebel, John E. "Using Aftershocks to Help Locate Historical Earthquakes." Seismological Research Letters 91, no. 5 (July 15, 2020): 2695–703. http://dx.doi.org/10.1785/0220200041.
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Abstract For historical earthquakes, the spatial distributions of macroseismic intensity reports are commonly used to estimate the event locations. The methods to locate historical earthquakes assume that the highest seismic intensity shows the best estimate of the location of the earthquake. Uncertainties in the locations estimated from macroseismic data can be due to an uneven geographic distribution of sites with intensity reports, variations in intensities due to local soil conditions, ambiguous historical reports, and earthquake directivity effects. Additional constraint on the location of a historical earthquake can come from places where most aftershocks were felt, because these localities may have been closest to the fault on which the mainshock took place. Examples of estimated earthquake locations based on aftershocks are those of the 1727 MLg 5.6 earthquake in northeastern Massachusetts, the MLg 5.7 earthquake in Maine, and the 1755 MLg 6.2 earthquake offshore of Cape Ann, Massachusetts. In all of these cases, the earthquake locations based on the aftershock data are somewhat different from previous locations derived from the macroseismic intensities alone. Uncertainties with this method include identifying aftershocks in historical accounts and the possibility that smaller events that are reported following a strong earthquake are not on or near the mainshock rupture. Even so, evidence of possible aftershock activity may help constrain the location of that mainshock. Because aftershocks of strong earthquakes (M≥7) can last months to years, archival research for aftershocks must be carried out with a somewhat different mindset than that for a mainshock.
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Kouskouna, V., A. Ganas, M. Kleanthi, I. Kassaras, N. Sakellariou, G. Sakkas, S. Valkaniotis, et al. "Evaluation of macroseismic intensity, strong ground motion pattern and fault model of the 19 July 2019 Mw5.1 earthquake west of Athens." Journal of Seismology 25, no. 3 (April 13, 2021): 747–69. http://dx.doi.org/10.1007/s10950-021-09990-3.
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AbstractThis paper presents a joint analysis of instrumental and macroseismic data regarding the 19 July 2019, Greece Mw5.1 earthquake occurred west of Athens. This earthquake ruptured a blind, south-dipping normal fault, 23 km WNW of the center of Athens, while its relocated epicentre lies in close vicinity to the one of the 1999 Mw6.0 earthquake. The maximum macroseismic intensity of the 2019 mainshock reached IEMS98 = 7.5. Scarce damage and intensities up to 5–6 were reported in the epicentral area. Higher intensities were observed at larger distances, 12–15 km east and ESE of the epicentre, alongside the banks of Kifissos River, likely related to ground motion amplification due to soft alluvial formations. Similar selectivity of increased ground motions to the east of the epicentre with respect to other azimuths, also observed during the 1981 and 1999 earthquakes, supports eastward rupture directivity of the 2019 mainshock, an effect that is possibly common for the region’s fault system. Damping of seismic effects was observed east of Aegaleo Mountain, a structure suggested to impose a stopping phase in the time histories of the 1999 and 2019 earthquakes (Fig. A1).
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Triantafyllou, Ioanna, Ioannis Koukouvelas, Gerassimos A. Papadopoulos, and Efthymios Lekkas. "A Reappraisal of the Destructive Earthquake (Mw5.9) of 15 July 1909 in Western Greece." Geosciences 12, no. 10 (October 10, 2022): 374. http://dx.doi.org/10.3390/geosciences12100374.
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Studies on earthquakes that occurred in the early instrumental period of seismology are of importance for the seismic hazard assessment and are still under investigation since new data are being increasingly revealed. We study the case of a moderate-to-strong earthquake that occurred on 15 July 1909 in NW Peloponnese, Greece. Although the earthquake event was quite destructive, it remains little-known so far in the seismological tradition. We compiled a variety of documentary sources and showed that the earthquake caused extensive building destruction in Chavari and in many other villages with an estimated maximum intensity IX (in EMS-98 scale) and a death toll as high as 55. We also assigned macroseismic intensities in several observation points and drew isoseismal lines by applying the nearest-neighbor technique. From empirical relationships between magnitude and intensities, we estimated the macroseismic magnitude of proxy Ms5.9. Our examination also revealed a variety of earthquake associated phenomena including several types of precursors and abundant co-seismic hydrological changes and ground failures, such as soil liquefaction, surface ruptures, and rock falls. Since no surface fault-trace was reported, the determination of the causative blind fault remains an open issue for future investigation.
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Musson, R. M. W., and P. H. O. Henni. "From questionnaires to intensities — Assessing free-form macroseismic data in the UK." Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy 24, no. 6 (January 1999): 511–15. http://dx.doi.org/10.1016/s1464-1895(99)00063-0.
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Papoulia, Joanna E., and Dario Slejko. "Seismic hazard assessment in the Ionian Islands based on observed macroseismic intensities." Natural Hazards 14, no. 2-3 (1997): 179–87. http://dx.doi.org/10.1007/bf00128265.
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Ertuncay, Deniz, Laura Cataldi, and Giovanni Costa. "Web-based macroseismic intensity study in Turkey – entries on Ekşi Sözlük." Geoscience Communication 4, no. 1 (February 22, 2021): 69–81. http://dx.doi.org/10.5194/gc-4-69-2021.
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Abstract. Ekşi Sözlük is one of the most visited websites in Turkey. Registered users of the website share their knowledge about any topic. In this study, we collect the user entries on the topic of 20 earthquakes in Turkey and the surrounding area. Entries with city and district level information are converted to intensity values. Shake maps of the earthquakes are created by using a ground motion to intensity conversion equation. User entries and created shake maps are compared. It is found that entries correlate with the predicted intensities. It is also found that local soil conditions and building types have an amplifier effect on entries on the website. Several entries on the earthquake topics have magnitude estimations. The difference between predicted and observed intensities also varies with distance. Users are able to predict the magnitudes of the earthquakes with ±0.54 misfit. This study shows that Ekşi Sözlük has the potential to be a reliable source of macroseismic intensity for the earthquakes in Turkey if the felt reports are collected with a predetermined format.
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Ribeiro, José R., Ana P. S. Correia, and Ana I. C. Ribeiro. "2 February 1816, an Overlooked North Atlantic M 8 Earthquake." Seismological Research Letters 91, no. 5 (July 15, 2020): 2912–21. http://dx.doi.org/10.1785/0220200201.
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Abstract The 2 February 1816 North Atlantic earthquake is virtually unknown to the international scientific community, and the few existing studies—solely based on two or three macroseismic intensities—pointed to a magnitude near 7 and a location at the eastern end of the Gloria fault in the Azores-Gibraltar Fracture Zone (AGFZ). Through careful search, we discovered more than 40 independent macroseismic observations and were able to estimate a total of 26 values of intensity, covering a wide geographical area (Iberian Peninsula, Madeira, and Azores). To apply the Bakun and Wentworth (B&W) method to the macroseismic dataset, we also deduced intensity–distance attenuation equations for the three different Atlantic coasts. The B&W procedure enabled us to conclude that the 2 February 1816 earthquake had a moment magnitude of 8.6±0.3 at the 95% confidence level and an epicentral location of 37.8° N and 19.8° W, near the central part of the Gloria fault. These results place the event as the greatest known earthquake in the Gloria fault domain and as one of the greatest ever seismic events along the AGFZ, probably only surpassed by the 1755 Lisbon earthquake.
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Voss, Peter H., Søren v, Trine Dahl Jensen, and Tine B. Larsen. "Recent earthquakes in Denmark are felt over as large areas as earthquakes of similar magnitudes in the Fennoscandian Shield and East European Platform." Bulletin of the Geological Society of Denmark 65 (October 31, 2017): 125–34. http://dx.doi.org/10.37570/bgsd-2017-65-08.
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For magnitude estimation of historical, pre-instrumental earthquakes it is useful to estimate felt areas for several intensities. From several macroseismic surveys it has been observed that an old shield such as the Fennoscandian Shield has especially large felt areas compared to California where the magnitude formula was developed. However, the newest Danish observations of felt areas and associated digitally determined magnitudes presented in this study show that the subsurface of Denmark has a response to shaking which is similar to that of the Fennoscandian Shield. This study covers the period 1996–2012 and includes an analysis of the macroseismic surveys of all felt earthquakes. Eight of these earthquakes provided new information on intensity areas in Denmark. An aim for the future is to use the felt areas of old earthquakes in Denmark for improved estimations of their magnitudes.
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Zaalishvili, Vladislav, and Yury Chernov. "The Influence of the Rate of Increase of Ground Vibration Accelerations During Earthquakes on the Value of the Observed Macroseismic Effect." Open Construction and Building Technology Journal 15, no. 1 (May 19, 2021): 70–80. http://dx.doi.org/10.2174/1874836802115010070.
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Aims: It is known that along with the traditionally considered amplitudes and durations of ground vibrations, the rate of increase in the intensity of ground vibrations in time can also affect the level of macroseismic effects caused by earthquakes. According to the previously obtained correlations, the differences between the observed macroseismic effects during earthquakes with slow and fast increases in the amplitude level of oscillations can reach one point of the macroseismic scale. The purpose of these study is to obtain, on the basis of a significantly (almost 9 times) larger than before, the volume of initial data (in combination with a more effective method of analysis) new and more accurate quantitative estimates of the studied dependences, as well as their possible interpretation. Background: The work continues the research began in 1985-1989. A representative statistical material was used, including 1250 accelerograms of earthquakes that occurred in different regions of the world, with magnitudes M = 2.5-7.7, distances of 5-230 km and independent estimates of macroseismic intensities I = 3-10 points by the MSK or MMI. Objective: Correlations between the absolute and relative rates of increase of ground vibration accelerations during earthquakes with different magnitudes and distances, on the one hand, and macroseismic effects caused by these vibrations, on the other, are considered. Methods: The study was carried out in the form of a direct statistical comparison of the parameters describing the form of ground vibrations during earthquakes with the characteristics of variations in macroseismic effects caused by these vibrations. A sample was formed and analyzed, including 1250 accelerograms of sensible and strong earthquakes recorded in various regions of the world and having independent estimates of the macroseismic intensity of shaking at instrumental registration sites. Results: It is shown that the macroseismic intensity of shaking can depend on the relative rate of increase of acceleration amplitudes in the general wavetrain of ground vibrations. An increase in the macroseismic intensity of shaking was observed with an increase in the relative rate of increase of the amplitudes and, conversely, it decreases with a slowdown in the rate of increase of the acceleration intensity. Similar constructions, made according to the data of the Time-Frequency Signal Analysis (TFSA) of 50 accelerograms of earthquakes with M = 3.3-6.2, a distance of 7-139 km and a macroseismic intensity of 4-7 MMI points, showed the same dependence, but clearer and with large coefficients of regression and correlation. The difference between earthquakes with “fast” and “slow” accelerations in the intensity I can reach one MSK point. Conclusion: The results of this study indicate that the rate of increase in the acceleration of ground vibrations during earthquakes can in a certain way affect the macroseismic effects. Earthquakes with slowly increasing amplitudes of ground vibration accelerations form average less macroseismic effects than those with rapidly growing accelerations. Variations in the shaking intensity, at the same time, are quite significant and can be compared with variations associated with differences in soil-geomorphological conditions, focal mechanisms, general seismotectonic conditions and other factors that are traditionally taken into account in detailed assessments of seismic hazard. Therefore, this factor should also be taken into account when conducting such studies.
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Stanko, Davor, Ivica Sović, Nikola Belić, and Snježana Markušić. "Analysis of Local Site Effects in the Međimurje Region (North Croatia) and Its Consequences Related to Historical and Recent Earthquakes." Remote Sensing 14, no. 19 (September 28, 2022): 4831. http://dx.doi.org/10.3390/rs14194831.
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The Međimurje region (North Croatia), situated between the Drava and Mura rivers with a slightly elevated hilly area, can be generally characterized as a low-seismicity area. However, macroseismic observations from historical and recent earthquakes indicate that some localities in this region are more prone to damage than others. Significant damage and the observed higher intensities in the Međimurje region after the historical earthquakes of 1738 MLm5.1 (Međimurje) and 1880 ML6.3 (Zagreb), and events that occurred in the instrumental era, 1938 ML5.6 (Koprivnica), 1982 ML4.5 (Ivanec), and the most recent 2020 ML5.5 Zagreb and 2020 ML6.2 Petrinja earthquakes, point to the influence of local site effects. There is a reasonable indication that these earthquakes involved several localized site effects that could explain the increased intensity of half a degree or even up to one degree at certain localities compared to macroseismic modeling for rock condition. To better understand the influence of local site effects in the Međimurje region, the single-station microtremor Horizontal-to-Vertical Spectral Ratio (HVSR) method for subsurface characterization was used. Based on individual measurements, microzonation maps were derived for the Međimurje region to better understand the behavior of ground motion and the influence of local site conditions in comparison to macroseismic intensities and past damage observations. Several local site effects could be interpreted as a main contribution to site amplification and resonance effects due to variations in deep soft-deposit thicknesses overlayed on hard deposits and directional variations in topographical areas that could localize earthquake damage patterns. Correlations of microtremor analysis with intensity observations from historical earthquakes as well with recent earthquakes could help to distinguish local site zones prone to the possible occurrence of higher earthquake damage from nearby and distant earthquakes.
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Silveira, D., J. L. Gaspar, T. Ferreira, and G. Queiroz. "Reassessment of the historical seismic activity with major impact on S. Miguel Island (Azores)." Natural Hazards and Earth System Sciences 3, no. 6 (December 31, 2003): 615–23. http://dx.doi.org/10.5194/nhess-3-615-2003.
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Abstract. On account of its tectonic setting, both seismic and volcanic events are frequent in the Azores archipelago. During the historical period earthquakes and seismic swarms of tectonic and/or volcanic origin have struck S. Miguel Island causing a significant number of casualties and severe damages. The information present in historical records made possible a new macroseismic analysis of these major events using the European Macroseismic Scale-1998 (EMS-98). Among the strongest earthquakes of tectonic origin that affected S. Miguel Island, six events were selected for this study. The isoseismal maps drawn for these events enabled the identification of areas characterized by anomalous values of seismic intensity, either positive or negative, to constrain epicentre locations and to identify some new seismogenic areas. Regarding seismic activity associated with volcanic phenomena six cases were also selected. For each of the studied cases cumulative intensity values were assessed for each locality. The distribution of local intensity values shows that the effects are not homogeneous within a certain distance from the eruptive centre, the area of major impacts relates with the eruptive style and damages equivalent to high intensities may occur in Furnas and Sete Cidades calderas. Combining all the historical macroseismic data, a maximum intensity map was produced for S. Miguel Island.
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Edwards, Benjamin, Helen Crowley, Rui Pinho, and Julian J. Bommer. "Seismic Hazard and Risk Due to Induced Earthquakes at a Shale Gas Site." Bulletin of the Seismological Society of America 111, no. 2 (January 19, 2021): 875–97. http://dx.doi.org/10.1785/0120200234.
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ABSTRACT Hydraulic fracturing of the first shale gas well at Preston New Road (PNR), Blackpool, United Kingdom, in late 2018, marked the end of a 7 yr United Kingdom-wide moratorium on fracking. Despite a strict traffic-light system being in place, seismic events up to ML 2.9 were induced. The ML 2.9 event was accompanied by reports of damage and was assigned European Macroseismic Scale 1998 (EMS-98) intensity VI by the British Geological Survey. The moratorium was subsequently reinstated in late 2019. The study here presents a pseudo-probabilistic seismic risk analysis and is applied to the larger of the induced events at PNR, in addition to hypothetical larger events. Initially, site characterization analysis is undertaken using direct and indirect methods. These analyses show low-velocity deposits dominate the region (VS30‾=227 m/s). We test existing ground-motion prediction equations using spatially dependent VS30 to determine applicability to the recorded waveform data and produce a referenced empirical model. Predicting median and 84th percentile peak ground velocity fields, we subsequently determine macroseismic intensities. Epicentral intensities of IV, IV–V, and VI–VII are predicted for the observed ML 2.9, and hypothetical ML 3.5 and 4.5 scenarios, respectively. A probabilistic analysis of damage is performed for 3500 ground-motion realizations (2.1≤ML≤4.5) using the OpenQuake-engine, with nonlinear dynamic analysis undertaken to define building fragility. Based on these analyses, the onset of cosmetic damage (DS1) in terms of median risk is observed for the ML 2.9 event. Mean modeled occurrences of DS1 and DS2 (minor structural damage), 75 and 10 instances, respectively, are consistent with reported damage (DS1:97, DS2:50). Significant occurrences (median≥30 buildings) of DS2, DS3, and DS4 (minor to major structural damage) are likely for ML 3.5, 4.0, and 4.5 events, respectively. However, by comparing reported damage with modeled damage due to the ML 2.9 event and considering the fact that low macroseismic intensities (EMS-98 <4) are often not reported by the public, we conclude that the previously assigned intensity of VI is too high, with V being more appropriate.
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Zobin, Vyacheslav M., and J. Francisco Ventura-Ramirez. "The macroseismic field generated by the Mw 8.0 Jalisco, Mexico, earthquake of 9 October 1995." Bulletin of the Seismological Society of America 88, no. 3 (June 1, 1998): 703–11. http://dx.doi.org/10.1785/bssa0880030703.
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Abstract The Mw 8.0 earthquake of 9 October 1995 occurred within the Jalisco block that represents the northern part of the Mexican subduction zone where the Rivera plate subducts beneath the North America plate along the Middle American trench. The source rupture of the 1995 low-angle thrust-type event was complicated. The studies of rupture history had shown that the slip occurred within an area of about 180 × 90 km2 along the Middle American trench at the depth interval from 9 to 33 km. The rupture duration was estimated in interval from 55 to 62 sec. At least three main asperities ruptured along the fault plane. The earthquake was felt along the 600-km coast of the Mexican states of Colima, Jalisco, and Michoacan and in the continental part of Mexico. The macroseismic study presented in this article was carried out in March through July 1997, more than one year after the earthquake. We had about 300 interviews with people who felt the earthquake in their houses located in 56 cities and towns of the states of Colima, Jalisco, and Michoacán. All our estimates of the earthquake intensity were referred to the intermediate type of masonry situated on the intermediate type of soils. For this purpose, corrections were introduced for type of soil and masonry. The study of macroseismic effects related to the 1995 Jalisco earthquake allows description of some properties of the macroseismic field generated by the earthquake. (1) Three zones of intensity 4, 5, and 6 to 7 grades of MM (Modified Mercalli) scale were distinguished. (2) The zone of maximum intensity of 6 to 7 MM was heterogeneous. This heterogeneity was in accordance with the rupture asperities distribution. (3) The study of intensity attenuation along the coast had demonstrated the asymmetry in intensity distribution according to the epicenter. The maximum intensities were observed for the sites that were situated to the northwest of the epicenter. (4) A good correlation was observed between the observed intensities and the values of GPS displacements.
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Carrasco, Sebastián, Sergio Ruiz, and Miguel Sáez. "Earthquakes Felt in the Juan Fernandez Islands: Where Are They Coming from?" Seismological Research Letters 91, no. 1 (November 13, 2019): 262–71. http://dx.doi.org/10.1785/0220190151.
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Abstract The Juan Fernandez Islands (JFI) are located in the Pacific Ocean 675 km west of the Chilean coast. This archipelago has historically been affected by large tsunamis. Robinson Crusoe Island (RCI), the main island of the JFI, was first inhabited in 1749. Since then, several tsunamis have destroyed RCI port structures and sometimes caused deaths. Ground shaking perceived by the inhabitants has preceded some tsunami arrivals. Seismological instrumentation was temporarily deployed on RCI in 1999, and a permanent station has been operating since 2014. Here, we use these data to characterize the seismic waves that arrive at the JFI and to determine whether shaking perception could be used as a tsunami early warning system. We compute peak ground accelerations (PGAs) from P, S, and T waves generated by Peruvian and Chilean earthquakes and find that the largest ground shakings are mostly related to T‐wave arrivals, which correlate with macroseismic modified Mercalli intensities lower than III. From the analysis of PGAs and macroseismic intensities, we conclude that shaking perception can be associated with large megathrust earthquakes, subduction events generated in the deep zone of seismogenic contact, and local seismicity. Unfortunately, potential tsunami earthquakes that occur on the Chilean coast will not be felt on RCI. Consequently, ground shaking in the JFI would not be a good proxy for tsunami warning, and a robust tsunami early warning system is necessary for RCI.
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Xin, Danhua, James Edward Daniell, and Friedemann Wenzel. "Review article: Review of fragility analyses for major building types in China with new implications for intensity–PGA relation development." Natural Hazards and Earth System Sciences 20, no. 2 (February 27, 2020): 643–72. http://dx.doi.org/10.5194/nhess-20-643-2020.
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Abstract. The evaluation of the seismic fragility of buildings is one key task of earthquake safety and loss assessment. Many research reports and papers have been published over the past 4 decades that deal with the vulnerability of buildings to ground motion caused by earthquakes in China. We first scrutinized 69 papers and theses studying building damage for earthquakes that occurred in densely populated areas. They represent observations where macroseismic intensities have been determined according to the official Chinese Seismic Intensity Scale. From these many studies we derived the median fragility functions (dependent on intensity) for four damage limit states of the two most widely distributed building types: masonry and reinforced concrete. We also inspected 18 publications that provide analytical fragility functions (dependent on PGA, peak ground acceleration) for the same damage classes and building categories. Thus, a solid fragility database based on both intensity and PGA is established for seismicity-prone areas in mainland China. A comprehensive view of the problems posed by the evaluation of fragility for different building types is given. Based on the newly collected fragility database, we propose a new approach in deriving intensity–PGA relations by using fragility as the bridge, and reasonable intensity–PGA relations are developed. This novel approach may shed light on new thought in decreasing the scatter in traditional intensity–PGA relation development, i.e., by further classifying observed macroseismic intensities and instrumental ground motions based on differences in building seismic resistance capability.
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Kalogeras, I. S., G. Marketos, and Y. Theodoridis. "A TOOL FOR COLLECTING, QUERYING AND MINING MACROSEISMIC DATA." Bulletin of the Geological Society of Greece 36, no. 3 (January 1, 2004): 1406. http://dx.doi.org/10.12681/bgsg.16509.
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SEISMO-SURFER is a tool for collecting, querying and mining seismic data being developed in Java programming language using Oracle database system. The objective is to combine recent research trends and results in the fields of spatial and spatio-temporal databases, data warehouses and data mining, as well as well established visualization techniques for geographical information. The database of the tool is automatically updated from remote sources while existing possibilities allow the querying on different earthquakes parameters, the analysis of the data for extraction of useful information and the graphical representation of the results via maps, charts etc. In the present work, we extend SEISMO-SURFER to include macroseismic data collected by the Geodynamic Institute and filled in a relative database. More specifically, the seismic parameters of the strong earthquakes, stored into the SEISMO-SURFER database, are linked to the macroseismic intensities observed at different sites. Administrative information for each site, local surface geology, tectonic lines, damage photographs and detailed descriptions from newspapers are also included. University of Piraeus and Geodynamic Institute are working together to continuously update and develop SEISMO-SURFER, concerning the data included, the variety of parameters stored and the mining algorithms supported for exploiting knowledge.
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Herak, Davorka, Mladen Živčić, Iva Vrkić, and Marijan Herak. "The Međimurje (Croatia) Earthquake of 1738." Seismological Research Letters 91, no. 2A (January 29, 2020): 1042–56. http://dx.doi.org/10.1785/0220190304.
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Abstract The 30 March 1738 earthquake with an epicenter near Čakovec in Međimurje (Croatia) is the largest known earthquake in the low-seismicity area that includes northernmost Croatia, northeastern Slovenia, southeastern Austria, and southwestern Hungary. So far, it has attracted very little attention in the seismological communities of those countries. It is missing or has wrong source parameters in all of the relevant earthquake catalogs (including the Seismic Hazard Harmonization in Europe (SHARE) catalog, Stucchi et al., 2013), which may influence seismic hazard assessment in this part of Europe, most critically in the Međimurje region itself. We present contemporary historical data shedding some light on the effects that the earthquake had on settlements mostly in Međimurje, but also elsewhere in Croatia, Slovenia, and Hungary. We were able to assign intensities to 12 localities surrounding the epicenter and to resolve the confusion about its date of occurrence. The intensity points were inverted for the location of the macroseismic hypocenter and epicentral intensity (I0=7.9 MSK [Medvedev–Sponheuer–Karnik]). The epicenter is found to lie on the hanging wall of the reverse Čakovec fault, about 6 km from its surface trace, and 8 km north-northwest of the town of Čakovec. The rather small felt area for an earthquake of this maximum intensity implies a shallow macroseismic focal depth of 6 km. These values of intensity and depth correspond to a macroseismic magnitude of MLm 5.1.
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Provost, Ludmila, and Oona Scotti. "QUake-MD: Open-Source Code to Quantify Uncertainties in Magnitude–Depth Estimates of Earthquakes from Macroseismic Intensities." Seismological Research Letters 91, no. 5 (May 6, 2020): 2520–30. http://dx.doi.org/10.1785/0220200064.
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Abstract This article presents a tool to quantify uncertainties in magnitude–depth (M-H) estimates for earthquakes associated with macroseismic intensity data. The tool is an open-source code written in Python and is named quantifying uncertainties in earthquakes’ magnitude and depth (QUake-MD). In QUake-MD, uncertainties are propagated from the individual intensity data point (IDP) to the final magnitude (M), depth (H), epicentral intensity (I0) solution. It also accounts for epistemic uncertainties associated with the use of different intensity prediction equations (IPEs). For each IPE, QUake-MD performs a sequential least-square inversion process to estimate the central M, H value. QUake-MD then explores the uncertainties around this central M, H solution by constructing a probability density function (PDF) constrained to be consistent with the range of plausible epicentral intensity I0, a plausible depth range, and IDP uncertainties. The resulting PDFs of all IPEs provided to QUake-MD are then stacked to obtain a final PDF of possible M, H, I0 solutions representative of both data quality and IPE epistemic uncertainties. This tool is geared toward end users who would like to grasp a more complete understanding of the uncertainties associated with historical earthquake parameters beyond the classical standard deviation values proposed today in parametric earthquake catalogs. We apply QUake-MD to two events of the SisFrance macroseismic database to illustrate the challenges involved in building realistic spaces of M, H, I0 solutions reflecting the quality of the data and the epistemic uncertainties in IPEs.
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Roumelioti, Z., and A. Kiratzi. "INCORPORATING DIFFERENT SOURCE RUPTURE CHARACTERISTICS INTO SIMULATIONS OF STRONG GROUND MOTION FROM THE 1867, M7.0 EARTHQUAKE ON THE ISLAND OF LESVOS (NE AEGEAN SEA, GREECE)." Bulletin of the Geological Society of Greece 43, no. 4 (January 25, 2017): 2135. http://dx.doi.org/10.12681/bgsg.11404.
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We apply the stochastic method for finite-faults (Beresnev and Atkinson, 1997, 1998) to simulate strong ground motion acceleration from the 1867 earthquake that devastated the Island of Lesvos in NE Aegean Sea. Recent geological data are taken into account to construct realistic models of the earthquake source, while a first-order approximation of the site effect variation throughout the entire island of Lesvos is achieved following an empirical approach suggested by Wald and Allen (2007). We test several source models including different segments of the Agia Paraskevi fault, which is most probably the seismogenic fault of the 1867 earthquake. Stronger ground motion is predicted in the central part of the island, i.e. around the assumed seismogenic structure. A significant site effect is evident along the eastern coast of Lesvos, where the capital of Mytilene lies, strongly hit by the 1867 earthquake, and around the gulfs of Kalloni and Geras in the south and southeast parts of the island. Synthetic peak ground acceleration values are converted to macroseismic intensities through an empirical relation and discussed in comparison with available reports on the macroseismic effects of the 1867 earthquake.
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Paradisopoulou, P. M., E. E. Papadimitriou, and J. Mirek. "SIGNIFICANT EARTHQUAKES NEAR THE CITY OF THESSALONIKI (NORTHERN GREECE) AND PROBABILITY DISTRIBUTION ON FAULTS." Bulletin of the Geological Society of Greece 50, no. 3 (July 27, 2017): 1389. http://dx.doi.org/10.12681/bgsg.11852.
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Stress triggering must be incorporated into quantitative earthquake probability estimate, given that faults are interacted though their stress field. Using time dependent probability estimates this work aims at the evaluation of the occurrence probability of anticipated earthquakes near the city of Thessaloniki, an urban center of 1 million people located in northern Greece, conditional to the time elapsed since the last stronger event on each fault segment of the study area. A method that calculates the macroseismic epicenter and magnitude according to macroseismic intensities is used to improve the existing earthquake catalog (from AD 1600 - 2013 with M≥6.0) in order to compute new interevent and elapsed time values which form the basis for time-dependent probability estimates. To investigate the effects of stress transfer to seismic hazard, the probabilistic calculations presented here employ detailed models of coseismic stress associated with the 20 June 1978 M=6.5 Thessaloniki which is the latest destructive earthquake in the area in the instrumental era. The combined 2015-2045 regional Poisson probability of M≥6.0 earthquakes is ~35% the regional time-dependent probability varies from 0% to 15% and incorporation of stress transfer from 0% to 20% for each fault segment.
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Simeonova, S. D., D. E. Solakov, G. Leydecker, H. Busche, T. Schmitt, and D. Kaiser. "Probabilistic seismic hazard map for Bulgaria as a basis for a new building code." Natural Hazards and Earth System Sciences 6, no. 6 (October 10, 2006): 881–87. http://dx.doi.org/10.5194/nhess-6-881-2006.
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Abstract. A seismic hazard map proposed as part of a new building code for Bulgaria is presented here on basis of the recommendations in EUROCODE 8. Seismic source zones within an area of about 200 km around Bulgaria were constructed considering seismicity, neotectonic and geological development. The most time consuming work was to establish a homogeneous earthquake catalogue out of different catalogues. The probabilistic seismic hazard assessment in terms of intensities is performed following Cornell (1968) with the program EQRISK (see McGuire, 1976), modified by us for use of intensities. To cope with the irregular isoseismals of the Vrancea intermediate depth earthquakes a special attenuation factor is introduced (Ardeleanu et al., 2005), using detailed macroseismic maps of three major earthquakes. The final seismic hazard is the combination of both contributions, of zones with crustal earthquakes and of the Vrancea intermediate depth earthquakes zone. Calculations are done for recurrence periods of 95, 475 and 10 000 years.
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KOYΣKOYNA, Β. "The (December 28th, 1891) January 9th, 1892 Larissa (Central Greece) earthquake." Bulletin of the Geological Society of Greece 34, no. 4 (January 1, 2001): 1425. http://dx.doi.org/10.12681/bgsg.17236.
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During the period 1941-1980 Thessalia (Eastern Central Greece) experienced a series of strong earthquakes, which caused damage to a large number of localities and to all its major towns. It is therefore characterized an area of moderate-to-high seismicity. In fact, low-to-moderate seismic activity was also observed in the 19th century, and there are a few sources reporting earthquakes in the area even in the centuries before. In the present study a damaging earthquake in the late 19th century is analyzed, in an effort to build up a detailed picture of the event and its supporting data set and to estimate its parameters with recent techniques. The 1892 shock damaged Larissa, situated in central Thessalia, caused minor damage to a few surrounding towns and was felt up to Thessaloniki to the north. The supporting datasets quoting the earthquake are evaluated according to their sources. Two sources reporting the earthquake, not quoted in the existing studies, were also located. In general, the earthquake effects are described in detail in two studies: one contemporary seismological compilation and one seismological compilation 60 years later, both based on contemporary press reports. The analysis is based on the original sources, contemporary to the earthquake. The macroseismic intensities were assessed using the EMS-98 scale and the focal parameters (magnitude, epicentral coordinates, epicentral intensity) were calculated using the Gasperini et al (1997,1999) method. This method allows for the calculation of earthquake parameters even for a limited number of macroseismic intensities, as in this case. The equivalent moment magnitude of the earthquake and the oriented "box", representing the surface projection of the seismogenic fault, were computed through empirical relations. The equivalent moment magnitude was calculated Mw=5.0, using two different empirical relations and the "boxer" technique, which takes into account all the available macroseismic data. The epicentral intensity of the earthquake was assessed to be I0=6-7 at Larisa and the epicentre was located at a close distance (8 km NE of the town). This location has also been proposed by Galanopoulos (1946), based on the assumption that the 1892 event originated from the same source as the 1941 Larisa earthquake. The calculated length of the associated fault was too small to be correlated with existing main tectonic features
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Villani, Manuela, Barbara Polidoro, Rory McCully, Thomas Ader, Ben Edwards, Andreas Rietbrock, Ziggy Lubkowski, Tim J. Courtney, and Martin Walsh. "A Selection of GMPEs for the United Kingdom Based on Instrumental and Macroseismic Datasets." Bulletin of the Seismological Society of America 109, no. 4 (July 16, 2019): 1378–400. http://dx.doi.org/10.1785/0120180268.
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Abstract In countries with low‐to‐moderate seismicity, the selection of appropriate ground‐motion prediction equations (GMPEs) to be used in a probabilistic seismic hazard analysis (PSHA) is a challenging step. Empirical observations of ground motion are limited, and GMPEs, when available, are generally based on stochastic simulations or adjusted empirical GMPEs from elsewhere. This article investigates the suitability of recent GMPEs to the United Kingdom. To this end, the spectral accelerations obtained from available instrumental ground‐motion data in the United Kingdom with magnitude lower than 4.5 are compared with the GMPEs’ predictions through the analysis of residuals and the application of statistical tests. To compensate for the scarcity of data for the magnitude range of interest in the PSHA, a macroseismic dataset is also considered. Macroseismic intensities are converted to peak ground acceleration (PGA) and statistically compared with the PGA predicted by the GMPEs. The GMPEs are then compared in terms of median ground‐motion prediction through Sammon’s maps to evaluate their similarities. The analyses from both datasets led to six suitable GMPEs, of which three are from the Next Generation Attenuation‐West2 project, one is European, one is based mainly on a Japanese dataset, and one is a stochastic GMPE developed specifically for the United Kingdom.
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Zamba, I., and V. Kouskouna. "Seismic history of Pel la and the 1st century B.C. earthquake." Bulletin of the Geological Society of Greece 40, no. 3 (June 5, 2018): 1318. http://dx.doi.org/10.12681/bgsg.16883.
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Research and evaluation of past and recent seismic records is required in order to obtain an overall picture of the seismic history of a given region. To this aim, important information can be collected through the study of monuments and the damage that they may have experienced during their history. Consequently, the archaeological reports on a hitherto unknown earthquake of the Is' century B.C. in Pella (northern Greece) are particularly interesting. These reports are based on the findings that came to light after the excavations of I.Akamatis in the region where the ancient town of Pella was laying. Beginning with this earthquake, this study tries to reach useful conclusions on the seismicity of Pella, in terms of macroseismic intensities from all earthquakes that have affected the town. For all these events, the intensity attenuation relations were used to calculate the macroseismic intensity in Pella. Although it is known a priori that the area is characterized as a relatively low seismicity area, the picture of its seismic history indicates the existence of damaging earthquakes with relatively large return periods. More specifically, in Pella the maximum observed intensity was found to be 7/8 during its seismic history, indicating the picture of low-to-moderate seismic hazard in the region.
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Herak, Marijan, Davorka Herak, and Mladen Živčić. "Which one of the three latest large earthquakes in Zagreb was the strongest – the 1905, 1906 or the 2020 one?" Geofizika 38, no. 2 (January 24, 2022): 117–46. http://dx.doi.org/10.15233/gfz.2021.38.5.
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Following the damaging earthquake of 22 March 2020 (ML = 5.5, Mw = 5.3, Imax = VII EMS) in Zagreb, a question was raised whether this was the largest event after the Great Zagreb earthquake of 1880 (Imax = VIII MSK). The countercandidates are the events of 17 December 1905 and 2 January 1906, for which relevant earthquake catalogues mostly report larger or comparable magnitudes as for the earthquake of 2020, with their maximum intensities mostly within a narrow margin between VII and VII–VIII in various intensity scales. In order to resolve the question, we have (re)analysed all available macroseismic data for the two historical events, collected readings from station bulletins, and analysed available historical seismograms. Macroseismic proxy for the local magnitude (MmR) was estimated on the basis of modelled radii of isoseismals V EMS and VI EMS using the regressions derived for a set of 12 earthquakes in NW Croatia and the neighbouring areas. Macroseismic magnitude was found to be the largest for the 1906 event (MmR = 5.3), followed by MmR = 5.1 for the 2020 quake. Considering the magnitudes computed after Wiechert seismograms from the Göttingen (GTT) station, and from the amplitude/period readings reported from the German stations JEN and HOH for the earthquake of 1906, as well as the magnitudes calculated from broad-band records of the GTTG station and the stations of the Croatian network for the event of 2020, a unified local magnitude of ML = 5.3 is found for both events. The magnitudes of the 1905 earthquake were consistently the lowest of the three. Taking the uncertainties into account, the events of 1906 and 2020 should be considered approximately equal in size. However, the strongest shaking in the centre of Zagreb was caused by the 2020 event. It occurred on the reverse North Medvednica boundary fault, while the macroseismic epicentres of earthquakes of 1905 and 1906 lie practically on the trace of the nearby strike-slip Kašina fault. That Kašina fault could have been the source of the 1906 earthquake is also hinted at by the elongated region of the strongest shaking along its strike.
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Harbi, A., S. Maouche, F. Ousadou, Y. Rouchiche, A. Yelles-Chaouche, M. Merahi, A. Heddar, et al. "Macroseismic Study of the Zemmouri Earthquake of 21 May 2003 (Mw 6.8, Algeria)." Earthquake Spectra 23, no. 2 (May 2007): 315–32. http://dx.doi.org/10.1193/1.2720363.
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The 21 May 2003 Zemmouri earthquake ( Mw=6.8), which killed 2,278 people, injured 11,450, made 250,000 homeless, and destroyed or seriously damaged 6,000 buildings and 20,800 housing units, is the most significant earthquake to affect Algeria since the 1980 El Asnam earthquake ( Ms=7.3). This paper presents the report of the macroseismic survey conducted by the Centre of Research in Astronomy, Astrophysics, and Geophysics (CRAAG, Algeria) immediately after the earthquake. The collected data set has led to a comprehensive evaluation of damage and estimation of intensity at about 600 sites, a number never reached in previous earthquake damage surveys. The produced isoseismal map portrays the spatial distribution of intensities from III to X EMS. A map highlighting the damage distribution, where various geological and hydrological phenomena are reported, is also presented. The extent of the socioeconomic impact of this event confirmed that Algerian buildings are highly vulnerable to the recurrence of destructive earthquakes.
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Sbarra, Paola, Patrizia Tosi, Valerio De Rubeis, and Diego Sorrentino. "Is an Earthquake Felt Inside a Car?" Seismological Research Letters 92, no. 3 (February 17, 2021): 2028–35. http://dx.doi.org/10.1785/0220200347.
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Abstract The analysis of how an earthquake is felt was addressed with the data provided by citizens through a website dedicated to the perception of earthquakes in Italy (Data and Resources). The analysis focused on the perception of earthquakes by observers inside both parked and moving cars. These situations were compared with outdoor ones. The felt percentage of each situation was quantified for epicentral distance ranges and European Macroseismic Scale (EMS) degree. One of the main findings was the greatest sensitivity to shaking for people inside parked cars due to resonance phenomena of the automobile–observer system. The distribution of the intensity of perception in the car was analyzed as a function of the hypocentral distance and the magnitude of the earthquake. It was possible to define the attenuation trends of these intensities. The comparison of these trends with those of the equations for estimation of response spectral ordinates allowed us to have an evaluation of the frequency values of the seismic waves that caused the vibrations felt, which were found to agree with the typical frequencies of the car–observer system, as highlighted by independent studies. The results of this analysis show the possibility to include the perception of the earthquake inside a parked and moving car among the diagnostics used in the definition of macroseismic intensity degree of the EMS.
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Ardeleanu, L., G. Leydecker, K. P. Bonjer, H. Busche, D. Kaiser, and T. Schmitt. "Probabilistic seismic hazard map for Romania as a basis for a new building code." Natural Hazards and Earth System Sciences 5, no. 5 (September 19, 2005): 679–84. http://dx.doi.org/10.5194/nhess-5-679-2005.
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Abstract. A seismic hazard map proposed as part of a new building code for Romania is presented here on basis of the recommendations in EUROCODE 8. Seismic source zones within an area of about 200 km around Romania were constructed considering seismicity, neotectonics and geological development. The probabilistic seismic hazard assessment in terms of intensities is performed following Cornell (1968) with the program EQRISK (see Mc Guire, 1976), modified by us for use of intensities. To cope with the irregular isoseismals of the Vrancea intermediate depth earthquakes a factor Ω is introduced to the attenuation law (Kövesligethy, 1907). Using detailed macroseismic maps of three earthquakes Ω is calculated by fitting the attenuation law to observed intensities, i.e. to local ground conditions. Strong local variation of Ω is avoided by a gridding of 0.5° in longitude and 0.25° in latitude. The contribution of the Vrancea intermediate depth zone to the seismic hazard at each grid point is computed with the corresponding representative Ω. A seismogenic depth of 120 km is assumed. The final seismic hazard is the combination of both contributions, of zones with crustal earthquakes and of the Vrancea intermediate depth earthquakes zone. Calculations are done for a recurrence period of 95, 475 and 10000 years. All maps show the dominating effects of the intermediate depth earthquakes in the Vrancea zone, also for the capital Bucharest.
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Papathanassiou, G., S. Valkaniotis, and S. Pavlides. "Applying the INQUA scale to the Sofades 1954, Central Greece, earthquake." Bulletin of the Geological Society of Greece 40, no. 3 (June 5, 2018): 1226. http://dx.doi.org/10.12681/bgsg.16875.
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Macroseismic intensity scales are used in order to measure the size of an earthquake using the impact of the ground shaking on humans, man made environment and nature. The INQUA scale is a new scale based solely on the earthquake-induced ground deformations, proposed by the INQUA Subcommission on Paleoseismicity. This scale is applied to the Sofades 1954 earthquake in order to test its accuracy and reliability. From the comparison among the evaluated intensities based on MM scale with the degrees of INQUA intensity at several locations, we conclude that, in case of earthquakes which triggered remarkable geological effects, these intensity values are about the same. Nonetheless, the use of INQUA scale is suggested in combination with the existing ones, as an assessing tool of the intensity based only on geological effects
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Sandoli, A., G. P. Lignola, B. Calderoni, and A. Prota. "Fragility curves for Italian URM buildings based on a hybrid method." Bulletin of Earthquake Engineering 19, no. 12 (June 18, 2021): 4979–5013. http://dx.doi.org/10.1007/s10518-021-01155-4.
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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.
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Iren-Adelina Moldovan, Angela Petruta Constantin, Raluca Partheniu, Bogdan Grecu, and Constantin Ionescu. "Relationships between macroseismic intensity and peak ground acceleration and velocity for the Vrancea (Romania) subcrustal earthquakes." Annals of Geophysics 64, no. 4 (November 16, 2021): SE432. http://dx.doi.org/10.4401/ag-8448.
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The goal of this paper is to develop a new empirical relationship between observed macroseismic intensity and strong ground motion parameters such as peak ground acceleration (PGA) and velocity (PGV) for the Vrancea subcrustal earthquakes. The recent subcrustal earthquakes provide valuable data to examine these relationships for Vrancea seismogenic region. This region is one of the most active seismic zones in Europe and it is well-known for the strong subcrustal earthquakes. We examine the correlation between the strong ground-motion records and the observed intensities for major and moderate earthquakes with Mw ≥ 5.4 and epicentral intensity in the range VI to IX MSK degrees that occurred in Vrancea zone in the period 1977-2009. The empirical relationships between maximum intensity and ground parameters obtained and published by various authors have shown that these parameters do not always show a one-to-one correspondence, and the errors associated with the intensity estimation from PGA/PGV are sometimes +/-2 MSK degree. In the present study, the relation between macroseismic intensity and PGA/PGV will be given both as a mathematical equation, but also as corresponding ground motion intervals. Because of the intensity data spreading and errors related to mathematical approximations, it is necessary to systematically monitor not only the acceleration and velocity but also all the other ground motion parameters. The mathematical relation between these parameters might be used for the rapid assessment of ground shaking severity and potential damages in the areas affected by the Vrancea earthquakes.