Scientific Data, 11, Article number: 834.

https://doi.org/10.1038/s41597-024-03692-4

{source}<span class="__dimensions_badge_embed__" data-doi="10.1038/s41597-024-03692-4" data-legend="always"></span><script async src="https://badge.dimensions.ai/badge.js" charset="utf-8"></script>{/source}

Abstract

Knowing the location, the extent and the characteristics of any earthquake-induced environmental phenomenon is becoming an increasingly pressing need for civil protection agencies and local administrations. In particular, earthquake-triggered landslides are known for being among the most important sources of secondary hazard, as they may cause significant losses and may delay rescue operations across large areas. The combination of the relatively frequent seismic release with a very high landslide susceptibility makes the Italian territory especially prone to the occurrence of earthquake-induced landslides. The CFTIlandslides dataset features over 1,000 landslides triggered by historical Italian earthquakes (up to 1997). The landslides effects are subdivided into classes based on location accuracy and type of movement. Knowing the distribution of the past earthquake-induced landslides provides the input information for assessing the related hazard. This dataset is addressed to a large audience of potential users, including researchers and scholars, administrators and technicians belonging to local institutions, and civil protection authorities.

Seismological Research Letters, Volume 92, Number 6.

DOI: https://doi.org/10.1785/0220210190

{source}<span class="__dimensions_badge_embed__" data-doi="10.1785/0220210190" data-legend="always"></span><script async src="https://badge.dimensions.ai/badge.js" charset="utf-8"></script>{/source}

Abstract
On 8 September 2020, the Italian media reported that the Court of Rieti, central Italy, found guilty with imprisonment between five and nine years the five defendants for the collapse of two public housing buildings and the death of 18 people, following the 24 August 2016 Mw 6.0 Amatrice earthquake; the first of a long‐lasting earthquake sequence featuring nine Mw 5 events, the largest being an Mw 6.5 near the town of Norcia. The court rejected a claim of exceptionality of the ground shaking put forward by the defendants and stated that the collapse was caused by “… well-identified design and building flaws, violating specific legal provisions and technical construction standards….”
.....

Tectonophysics, 774, article id. 228189

DOI: https://doi.org/10.1016/j.tecto.2019.228189
{source}<span class="__dimensions_badge_embed__" data-doi="10.1016/j.tecto.2019.228189" data-legend="always"></span><script async src="https://badge.dimensions.ai/badge.js" charset="utf-8"></script>{/source}

Abstract
Large earthquakes occur rather orderly in space and time; hence they can be somehow anticipated, and their effects can be projected into the future. The modern practice of seismic hazard assessment rests on these principles and may rely on them, but also requires a detailed knowledge of the location and characteristics of individual earthquake sources.
We discuss how this knowledge base can be constructed, with an eye on the geological history, which provides a record of the faults capable of generating large earthquakes, and one on the human history, which supplies evidence for whether, where and how these faults have actually caused damaging earthquakes in the past.
How do these two records interact with each other? It is now accepted that identifying active and potentially seismogenic faults in Italy is especially hard. The geological record may be clear and honest when dealing with processes at the scale of several million years, but can be very difficult to decipher if we are concerned with contemporary geological processes, such as earthquakes.
Shortening the tim E-W indow of observation of earthquake activity is why Historical Seismology is so crucial for constructing a seismogenic source model. To this end we exploited a number of key Italian destructive earthquakes, each of which illuminates a recent geological process that may not offer a discernible surface signature. Our findings led us to reconsider the tectonic style of large areas, changed our perception of their earthquake potential, hinted at the existence of unknown seismogenic zones, and even led to downsizing the magnitude of the largest Italian historical earthquakes.
We maintain that the complexity of the geological setting may be counterbalanced by the richness of the historical earthquake record. We also believe that our experience in the combined investigation of Italy’s historical earthquakes and seismogenic sources may be replicated in all earthquake-prone countries that exhibit a history of human settlement throughout the millennia.

Scientific Data, 6, Article number: 80.

DOI: https://doi.org/10.1038/s41597-019-0091-9

{source}<span class="__dimensions_badge_embed__" data-doi="10.1038/s41597-019-0091-9" data-legend="always"></span><script async src="https://badge.dimensions.ai/badge.js" charset="utf-8"></script>{/source}

Abstract
A key element for assessing seismic hazard and risk is the availability of a comprehensive dataset on past earthquakes. Here we present the rationale, structure and contents of CFTI5Med (https://doi.org/10.6092/ingv.it-cfti5), the 2018 version of the Catalogue of Strong Earthquakes in Italy: a large multidisciplinary effort including historians, seismologists and geologists. It was conceived in 1989, following the inception of GIS technology, and first published in 1995 to offer a full account of Italy’s strongest earthquakes, of their territorial impact and associated social and economic upheaval. Subsequent versions (1997, 2000, 2007) entailed a fine tuning of research methodologies, included additional research on Italian earthquakes, and were extended to large earthquakes of the Mediterranean area. CFTI5Med comprised an opportunity to streamline the structure of the Catalogue database and propose a renovated user interface. The new front-end (1) grants an easier, intuitive access to the data, including earthquake effects on the environment, and (2) allows all data to be displayed jointly with relevant topographic, geological and seismological overlays published as web services.

Scientific Reports, 9(1).

DOI: https://doi.org/10.1038/s41598-019-51966-4

{source}<span class="__dimensions_badge_embed__" data-doi="10.1038/s41598-019-51966-4" data-legend="always"></span><script async src="https://badge.dimensions.ai/badge.js" charset="utf-8"></script>{/source}

Abstract
Determining the hypocentral depth of pre-instrumental earthquakes is a long-standing geophysical issue that still awaits to be elucidated. Using very well documented recent earthquakes we found that the depth of crustal and upper-mantle events correlates well with the slope of the first 50 km of their intensity attenuation curve, regardless of their magnitude. We used this observation to build a magnitude-independent method for calculating the depth of selected historical and early-instrumental earthquakes of northern Italy based on their macroseismic intensity field. Our method relies on both standard intensity data and questionnaire-based data for 20 earthquakes, encompassing a relatively large range of magnitude (Mw 4.0–5.8) and depth (3.0–72.4 km), that occurred in Northern Italy between 1983 and 2019. We then used the method to estimate the depth of 20 older earthquakes that occurred in the same region between 1570 and 1972. Knowing the approximate depth of historical earthquakes is crucial for assigning them to the relevant seismogenic source, especially where seismogenic faults occur at different depths, allowing for a better characterisation of the region’s seismotectonic setting. Knowing the focal depth also allows recalculating the equivalent magnitude, which turns out to be consistently larger for deeper events, suggesting a reassessment of the local seismic hazard.

In:  A. Calzona, G. M. Cantarella e G. Milanesi, “Terremoto in Val Padana, 1117, la terra sconquassa e sprofonda”, Scripta Edizioni Verona, ISBN 978-8831933-12-4, 31-48

http://hdl.handle.net/2122/11991

Abstract
Il 20 maggio 2012 un terremoto di magnitudo 5,9 ha colpito una vasta zona della Pianura Padana compresa tra le provincie di Modena, Ferrara e Mantova. Oltre a diversi centri storici, a numerose chiese e ad alcuni capannoni industriali il terremoto ha mandato in frantumi anche la diffusa convinzione che quella porzione del territorio padano, da sempre flagellata da alluvioni e dove appena 50 anni fa si è conclusa l’ultima di una serie di bonifiche, fosse almeno immune dal rischio dei terremoti. Negli anni successivi in molti si sono chiesti quale sia il reale livello della sismicità naturale della Pianura Padana, e uno dopo l’altro sono stati riscoperti terremoti antichi ma non per questo meno disastrosi come quelli che hanno distrutto Ferrara nel 1570, Argenta nel 1624, Cotignola nel 1688. Nel 2017, con il novecentesimo anniversario del terremoto del 1117, si sono accesi i riflettori anche sulla più disastrosa crisi sismica mai avvenuta nella Pianura Padana, innescando nuove analisi e riflessioni sul passato sismico dell’area più popolosa del nostro paese, e dunque anche sul futuro. Il livello non trascurabile della pericolosità sismica di alcune porzioni della Pianura Padana è stato chiaramente messo a fuoco dalle analisi della comunità scientifica già dal 2003, quando è stata pubblicata l’Ordinanza della Presidenza del Consiglio dei Ministri n. 3274, e successivamente dalla Mappa di Pericolosità Sismica elaborata dall’Istituto Nazionale di Geofisica e Vulcanologia (d’ora in avanti INGV) e nota come MPS04.1 La normativa sismica ancora oggi in vigore ha prontamente recepito le novità, ma una serie di ritardi e sostanziali sottovalutazioni del problema da parte degli amministratori hanno fatto in modo che il tema non entrasse nel dibattito pubblico almeno fino al maggio 2012. All’evoluzione delle conoscenze, e soprattutto della consapevolezza del problema sismico da parte dei cittadini e dei loro amministratori, è dedicata un’intera sezione del volume L’Italia dei disastri, curato da Emanuela Guidoboni e Gianluca Valensise e pubblicato nel 2013.2 Come ricercatori impegnati nella caratterizzazione sismica del territorio italiano3 da quasi due decenni abbiamo cercato di comprendere a cosa sia dovuta la scarsa percezione della sismicità di quell’ampia e importante porzione del nostro territorio nazionale che costituisce la Pianura Padana. A parte la relativa rarità dei forti terremoti, quantomeno negli ultimi tre secoli, va sicuramente considerato anche un diffuso approccio – più romantico che naturalistico – che tende a vedere nelle blande variazioni topografiche di quei territori la prova che il contesto geologico e geodinamico locale sia altrettanto ‘tranquillo’. Ma come dimostrano i terremoti che sono stati appena ricordati, questo punto di vista è del tutto sbagliato. Il paesaggio geologico sepolto della Pianura Padana è in effetti molto articolato e complesso, ed è sede di processi geodinamici certamente attivi; possiamo immaginarlo costituito da vere e proprie montagne ammantate da grandi quantità di sedimenti di origine marina e fluviale. Questi sedimenti hanno spessori molto variabili – da poco più di 100 metri a diverse migliaia di metri – e con la loro presenza obliterano le strutture tettoniche sottostanti. Queste possono in ogni caso essere rilevate e indagate quantomeno per via indiretta grazie alle numerose prospezioni geofisiche che sono state realizzate e rese disponibili dall’esplorazione petrolifera a partire dal secondo dopoguerra.

In: A. Fiore e V. Ottaviani (a cura di), “Rischio sismico in Italia: analisi e prospettive per una prevenzione efficace in un Paese fragile”, ISSN 1591-5352, suppl. al n. 1/2018 di Geologia dell’Ambiente, Periodico trimestrale della SIGEA Società Italiana di Geologia Ambientale,  28-34.

https://www.sigeaweb.it/documenti/gda-supplemento-1-2018.pdf

International Journal of Disaster Risk Reduction

Geologia tecnica & ambientale, Quadrimestrale dell’Ordine Nazionale dei Geologi, n. 1/2018, 21-31.

http://www.cngeologi.it/wp-content/uploads/2018/08/GTA01_2018_web.pdf

Il lavoro è presentato da Gianluca Valensise sul Blog "Terremoti e grandi rischi" - link

In: M. Rai (a cura di), “Il terremoto del 13 gennaio 1915 nell’Alta e Media Valle del Liri”, 2voll., Vol.I, 39-75.

Bulletin of Earthquake Engeneering, 13, 2769–2803.

DOI: https://doi.org/10.1007/s10518-015-9759-5

{source}<span class="__dimensions_badge_embed__" data-doi="10.1007/s10518-015-9759-5" data-legend="always"></span><script async src="https://badge.dimensions.ai/badge.js" charset="utf-8"></script>{/source}

Abstract
We apply a computer-aided methodology to assess macroseismic intensity from the descriptions reported by documentary material available for eight Italian earthquakes occurred around the beginning of the instrumental era. The procedure consists of three phases: (i) the identification of significant macroseismic effects on the sources and their archiving in a georeferenced database, (ii) the association between the effects and the degrees of the intensity scale by the comparison with traditional estimates made by macroseismic experts, (iii) the assessment of intensities using a multi-attribute decision-making algorithm based on the Fuzzy Sets logic. This work represents a substantial improvement of our previous efforts as we completely redesigned the three phases of the procedure in the light of the experience of the last 10 years and analyzed six further Italian earthquakes so that our database now includes more than 19,000 encoded effects. Our formalized procedure allows to tracing all of the steps of intensity assessment process so that to identify discrepancies with respect to the expert evaluations that might be possibly due to mistakes or to the incomplete account of the available information. Hence, this approach may be useful for providing a systematic and reproducible intensity assessment as well as for supporting standard man-made assessments. The database of effects we have built could also be employed for testing the internal consistency of the macroseismic scale as well as for designing an improved macroseismic scale, based on consistent statistical criteria.

Earthquake and Structures, 8(1), 153-184.

DOI: https://doi.org/10.12989/eas.2015.8.1.153

Abstract:
Most damaging earthquakes come as complex sequences characterized by strong aftershocks, sometimes by foreshocks and often by multiple mainshocks. Complex earthquake sequences have enormous seismic hazard, engineering and societal implications as their impact on buildings and infrastructures may be much more severe at the end of the sequence than just after the mainshock. In this paper we examine whether historical sources can help characterizing the rare earthquake sequences of pre-instrumental times in full, including fore-, main- and aftershocks. Thanks to the its huge documentary heritage, Italy relies on one of the richest parametric earthquake catalogues worldwide. Unfortunately most current methods for assessing seismic hazard require that earthquake catalogues be declustered by removing all shocks that bear some dependency with those identified as mainshocks. We maintain that this requirement has led most modern historical seismologists to focus mainly on mainshocks rather than also on the fore- and aftershocks. To shed light onto major earthquake sequences of the past, rather than onto individual mainshocks, we investigated 10 damaging earthquake sequences ($M_w$ 수식 이미지 4.7-7.0) that hit the L'Aquila area and central Abruzzo from the 14th to the 20th century. We find that most of the results of historical research are important for modern seismology, yet their rendering by the current parametric catalogues causes most information to be lost or not easily transferred to the potential users. For this reason we advocate a change in current strategies and the creation of a more flexible standard for storing and using all the information made available by historical seismology.

In: T. Riis (a cura di), “The ‘Dead Cities’ of Northern Syria and Their Demise”, Proceedings of the Institute in Damascus X, Ed. Ludwig, Kiel, ISBN: 978-3-86935-259-6, 61-109.

Abstract
Syria, in particular the area of Aleppo and the northwestern region on the border of present-day Turkey, is one of the most seismic areas in the eastern Mediterranean. This paper presents the effects of major earthquakes that occurred from the 7th up to the beginning of the 15th century AD, which struck Aleppo and the sites of Harim, Atarib, Zaradna and Ma‘arrat an-Nu‘man, not far from the “Dead Cities”, an area of abandoned settlements in northwest Syria between Aleppo and Idlib. During the first centuries of the Muslim conquest of Syria (7th-8th century AD) information on seismic effects regarding the city of Aleppo is scarce: it derives from a single source or from certain very late (12th-13th century) Arab and Syriac sources. In fact there are many information gaps not filled by the written sources available. Much more detailed are the numerous Arab sources of the twelfth century, contemporary or slightly later to seismic events they describe. The major seismic crisis that hit Syria during the twelfth century, culminating in the earthquake of 29 June 1170, in Aleppo had more destructive effects than the entire period examined here.

DOI: https://doi.org/10.1785/0220140074

Abstract
The article by Camassi and Castelli (2013) (hereinafter CC13) deals with the 1346, northern Italy earthquake, one of hundreds of medieval earthquakes that were investigated in Italy from 1983 to 2007. Regrettably, the article does not add any new data but only proposes a revision and a reinterpretation of published materials. CC13 first criticized the variability of magnitude estimates assigned to this earthquake in catalogs published in Italy over the past 20 years, then went so far as to question whether the 1346 earthquake actually occurred. Their analysis, however, is fraught with demonstrable mistakes in the analysis of medieval texts, such that their conclusions are objectionable both from the point of view of historical criticism and from that of historical seismology. Such conclusions may critically affect the assessment of seismic hazard in a heavily populated and industrialized portion of the Po Plain (northern Italy), right at a time when the threat posed by strong earthquakes in this region is being rediscovered by the citizens and by their administrators following the 20 and 29 May 2012, Emilia events (M w6.0 and 5.9). As the coauthors of the catalogs being questioned, we feel an obligation to reestablish what is the evidence supporting 1346 being a real major earthquake and why its magnitude is still uncertain.

Annals of Geophysics, 55, 3, 461-468

DOI: https://doi.org/10.4401/ag-5654

Abstract
On December 16, 1857, an earthquake wreaked havoc across a huge area of the regions of Basilicata and Campania (Val d’Agri and Vallo di Diano). More than 180 villages in an area of over 20,000 km2 suffered very severe damage. More than 6,000 houses collapsed or became uninhabitable, and 19,000 people were killed. In the months of February and March 1858, the Irish engineer Robert Mallet undertook a mission to study the earthquake with a grant from the Royal Society of London. In 1862, he published his extraordinary study diary, in which the technical and scientific observations mingled with descriptive and literary details. This represents, from different angles, a unique ‘observatory’ over the landscape and the social, economic and cultural aspects of Val d’Agri and Vallo di Diano. In 2003, the Provinces of Salerno and Potenza started up a joint venture with the Storia Geofisica Ambiente of Bologna and with the scientific partnership of the Istituto Nazionale di Geofisica e Vulcanologia, with a view to setting up provincial laboratories dedicated to environmental education, and named after Robert Mallet. The Mallet Project proceeded up to 2009 on three agreements. Within the framework of the idea of a ‘Mallet Laboratories’ Project, there has been the opportunity to set up a network of study centers in the territories of these two provinces (Salerno and Potenza), which can promote research with great national and international breadth, starting with the world of schools and local communities. The study entitled Viaggio nelle aree del terremoto del 16 dicembre 1857 was published through the period from 2004 to 2009.

Bull. Seism. Soc. Am., 102 (4), 1600–1617.

DOI: https://doi.org/10.1785/0120110173

Abstract
This historical seismology study examines and supplements what is currently known from written sources and archaeological literature about the earthquakes that took place in the area of L’Aquila (central Italy), struck by a damaging earthquake on 6 April 2009 (Mw 6.3), from the ancient Roman period to the late Middle Ages (first through fifteenth century A.D.). The persistence and magnitude of earthquakes in this area has had a strong bearing on the economy and culture of the communities that resided there, a fact borne out by historical accounts. The goal of this revision is to prompt thinking about earthquakes missing from the hazard estimates as well as on return periods for destructive earthquakes in the area. It presents a critical collation of data previously scattered among historical catalogs and writings. Ten earthquakes are examined for their historical and cultural background with a view to highlighting the existence of written sources and explaining both the quality of the available data and the information shortfall. We also show the limits and uncertainty of the information available, coming as it does from tersely written texts giving patchy coverage. This state of knowledge is due either to sources being lost or in certain centuries not being produced (there is a millennium of “lost” earthquakes) and to the present state of historical and archaeological research in this field. The historical and archaeological data we present are often poor/hard to quantify. Yet they are known and hence pose the problem of how to improve the earthquake catalogs and devise new quantitative approaches to hazard estimation based on multi‐disciplinary dialog.

Atti del Congresso dell’Associazione Italiana di Storia Urbana (AISU), Sessione i: I disastri di origine naturale

Abstract
La risposta sismica all’interno di un’area ridotta, come quella urbana, può avere un carattere ricorrente, anche a causa di terremoti diversi? La domanda non è banale e presuppone di confrontare diversi scenari di danni avvenuti in una stessa area urbana, in periodi diversi. Il tentativo di evidenziare su base storica se esiste una risposta sismica tipica dell’Aquila ci ha suggerito di localizzare a scala di edifici i danni subiti per due terremoti, ben documentati nella storia della città. Sono stati scelti gli eventi sismici del novembre 1461 (Me 6.3, come il terremoto del 6 aprile 2009 e come questo preceduto da mesi di scosse) e il terremoto del 2 febbraio 1703 (Me 6.7). Questo ultimo grande evento sismico seguì di pochi giorni altri due violenti terremoti, accaduti il 14 e 16 gennaio 1703, che colpirono l’Umbria meridionale e il Lazio settentrionale. Gli effetti all’Aquila sono classificati per il terremoto del 1461 di IX grado MCS e per quello del febbraio 1703 di X MCS. Il primo epicentro è situato nella media valle del fiume Aterno, a sud-est rispetto alla città; il secondo si trova a 12 km a nord-ovest dell’Aquila. Si tratta quindi di sorgente sismiche diverse. Per entrambi questi due disastrosi eventi i danni agli edifici importanti della città (chiese, palazzi, monasteri) sono descritti da fonti contemporanee con elevato dettaglio, elemento che consente di delineare i due scenari di danno in modo preciso, rendendo confrontabili di dati. Le due mappe consentono quindi di paragonare gli effetti urbani anche con quelli causati dal terremoto del 2009, fornendo indicazioni importanti sulla risposta sismica dell’Aquila.

Bulletin of Volcanology, 73, 655–677.

DOI: https://doi.org/10.1007/s00445-010-0430-3

Abstract
This paper presents the results of a systematic historical study of the seismic, bradyseismic and eruptive activity of the Campi Flegrei caldera. The aim is to make a revised historical data available for accurate volcanological interpretation, supplying additional data and highlighting spurious previous data. The analysis begins with the supposed 1198 eruption, which did not actually take place. No information is available for the thirteenth and fourteenth centuries. As far as the fifteenth and sixteenth centuries are concerned, only direct sources were examined for this paper, and they include many different types of evidence. The chronological breadth of the analysis has also provided information about the seismic crises and bradyseisms prior to the eruption of 1538. The exceptional nature of this 1538 eruption attracted the attention of intellectuals, diplomats and natural philosophers, who left valuable accounts, which we have analysed, and which include many that are still available in their original manuscript form. The previous studies concerning the 1538 eruption were based on 23 (variously used) sources. We have examined 35 additional sources bringing the overall corpus of sources analysed to 58. The results provide a more precise scenario of events preceding the 1538 eruption, including bradyseismic activity starting from the end of the fifteenth century. The chronology of the phenomena described comprises the core result of this study, and has been constructed so as to clarify the time, location and impact of each event. For the 1538 eruption, a countdown is included which may also have a predictive value. For the last 36 hours before eruption began, the countdown is hour-by-hour. The effects of the eruption and earthquakes on people, structures and society are also described for Pozzuoli, Agnano and Naples. The areas where heavy materials and ash fell are likewise indicated, as well are the earth tremors felt by the population from the eruptive crisis up to 1582.

Israel Journal of Earth Sciences, 58, 327-354.

DOI: https://doi.org/10.1560/IJES.58.2-3.327

Abstract
We present here a  compilation of known, reliable, historically documented tsunamis that have affected the Levant coast between about the 14th  century B.C. in Syria, up through the 1956 Jaffa tsunami. The list is based on a  careful review of published studies and  catalogs that have previously reappraised the original contemporaneous sources. In total, 23 events are included within our compilation, whereas 40 other events were found questionable and excluded.We first describe the dependable tsunamis in detail, including their probable source, whether they were generated from a  close or distant earthquake source, or whether they were likely the consequence of an earthquake-triggered submarine slump. This is followed by a  critical evaluation of the dubious (uncertain)  tsunami reports, as an aid to future investigations that may include a  search for new data, fieldwork, modeling and hazard assessments. Next, the list is parameterized in accordance with the format used by the tsunami catalog of the European community. Finally, the historical descriptions are used to assess the impact and effects caused by the tsunamis. The most regularly mentioned (about 90%)  is a  significant change in sea level. Damage and loss of life in coastal cities and harbors are reported for only one third of the events, leading to the conclusion that the majority of tsunamis on the Levant coast may have resulted in only moderate to no damage. Yet, this is  not to mean that the Levantine coast is not at risk. The modern coastline is now far more populated and developed than before, and a  similar tsunami that resulted in only moderate damage in the past might be more disastrous in the same location at present.

Bull. Seismol. Soc. Am., 100, 2035-2066.

DOI: http://dx.doi.org/10.1785/0120090330

Abstract
We herein describe new methods for computing the quantitative parameters of earthquakes using macroseismic data and the uncertainties associated with these parameters. The methods allow for the location of epicenters that are offshore or that have no intensities assigned to any points in the epicentral region by maximizing the likelihood function of an attenuation equation with observed intensity data. In the most favorable cases, such an approach also allows the estimation of the source depth and the local attenuation coefficients. We compute the parameter uncertainties in two ways: (1) using formal methods, such as the inversion of the Hessian of the loglikelihood function at its maximum, and (2) by using bootstrap simulations.We tested the performance of our methods by comparison with reliable instrumental hypocenters of onshore earthquakes, and found a reasonable agreement with the epicentral locations (within 10–15 km for more than 70% of cases) but not with the hypocentral depths, for which our results are generally underestimated by a factor of 2 or more and are poorly related to instrumental estimates. This finding indicates that the use of macroseismic depths in seismic hazard and seismotectonic investigations should be treated with caution. We nevertheless found good agreement (within 10°–15°) between the fault-trace orientations that were computed using the macroseismic data and the associated focal mechanisms of earthquakes with Mw ≥5:7. The surprising accuracy of the macroseismic orientations obtained using this method could in some cases allow the true fault to be inferred between the two conjugate planes of a given focal mechanism.