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The 6 February 1971 Tuscania (central Italy) earthquake belongs to a peculiar family of destructive seismic events that have occurred in an area classified as low-seismic hazard, causing heavy damage and tens of casualties. However, this earthquake took place at the dawn of modern seismology in Italy and is far from being fully characterized from an instrumental and macroseismological point of view. This article aims at bridging the gap of information that affects that earthquake, through a twofold research path: (1) with an archival investigation looking for new available sources and with the use of the European Macroseismic Scale-98 (EMS-98) intensity scale, and (2) with the calculation of a more constrained hypocentral location. The results of this investigation can be summarized as follows: the reappraisal of the earthquake in terms of EMS-98 provides a maximum intensity 8 in Tuscania (previously quoted 8–9 Mercalli–Cancani–Sieberg [MCS] in the catalog), and a general decrease of intensity in many damaged localities. The new epicenter location is shifted almost 10 km southeast of the old one, at about 3 km depth. This new location is more robust than the previous one and is consistent with the general distribution of the most damaged localities; however, we cannot exclude that effects of directivity might have played a role in the peculiar pattern of damage caused by the event. Finally, we provide new values of magnitude (MD 4.9 and ML 5.1) that point to an upward scaling of the earthquake. The ultimate lesson of this work is that a deepening of the research can always provide room for an improvement of our knowledge even for significant earthquakes that have occurred relatively recently.

The 8 September 1905 Calabria earthquake is the seismic event for which the Italian Seismic Catalogue shows the highest instrumental magnitude of the whole dataset. However, the reported Ms=7.47 was calculated over only two stations, and leaves room for a revision. In this work I provide a new estimate of the surface-wave magnitude of the earthquake calculated over sixteen individual values of magnitude from seven different stations. The new estimate is Ms=7.06±0.13, a value that is consistently lined up with other estimates provided by means of macroseismic or geological evidence. The novel estimate is stable despite alternative epicentral locations and different depths proposed for this event by several investigators. The net variation of almost half a unit magnitude implies a resizing of the seismogenic source of the event in the frame of the seismotectonics of the region, and highlights the strong need for a systematic revision of the instrumental magnitude estimates for several ‘historical’ earthquakes that occurred at the dawning of the instrumental seismology.

We present a 1:10,000 scale map of the coseismic surface ruptures following the 26 December 2018 Mw 4.9 earthquake that struck the eastern flank of Mt. Etna volcano (southern Italy). Detailed rupture mapping is based on extensive field surveys in the epicentral region. Despite the small size of the event, we were able to document surface faulting for about 8 km along the trace of the NNW-trending active Fiandaca Fault, belonging to the Timpe tectonic system in the eastern flank of the volcano. The mapped ruptures are characterized in most cases by perceivable opening and by a dominant right-oblique sense of slip, with an average slip of about 0.09 m and a peak value of 0.35 m. It is also noteworthy that the ruptures vary significantly in their kinematic expression, denoting locally high degree of complexity of the surface faulting.

I study the coseismic hydrological changes associated with two M6.7 earthquakes that occurred in 1805 and in 1930 in the Southern Apennines of Italy to provide additional constraints on the geometry and mechanism of their causative faults. The two earthquakes originated remarkable datasets of 84 and 52 observations of hydrological changes. I discounted those observations potentially affected by the geomorphological, climatic and methodological contamination of data. Then, I compared the distribution of the streamflow changes with the coseismic strain field induced by a number of seismogenic sources proposed for the two earthquakes. A first important outcome of this study is that it provides evidence against some of the seismogenic structures previously associated with the 1805 and 1930 earthquakes. In addition, for the 1805 earthquake, I find that ~300°-striking, NE-dipping, ∼30–35 km-long seismogenic structures consisting of four to five surface-rupturing normal fault segments best explain (with almost 75% consistency) the distribution of the observed hydrological data. However, I also find that almost 100% of the observations are consistent with the deformation imposed by the three southernmost segments and suggest that most of the seismic release during the 1805 event was provided by those segments only. For the 1930 earthquake, I find that the pattern of the coseismic hydrological changes is best fitted by the only fault characterized by ~E-W trending, oblique slipping, NE-dipping, and a shallow top of fault. The depth of the top of the fault plays an important role in the generation of more pronounced fields of deformation, even for those faults that do not rupture up to the free surface, as in the 1930 case. This study confirms that the hydrological signatures of earthquake strain provide supplemental constraints in the estimating geometry and faulting style of major historical earthquakes that produced large and documented amounts of hydrological data.

This multi-disciplinary work provides an updated assessment of possible future eruptive scenarios for the city of Rome. Seven new 40Ar/39Ar ages from selected products of the Monti Sabatini and Vulsini volcanic districts, along with a compilation of all the literature ages on the Colli Albani and Vico products, are used to reconstruct and compare the eruptive histories of the Monti Sabatini and Colli Albani over the last 900 ka, in order to define their present state of activity. Petrographic analyses of the dated units characterize the crystal cargo, and Advanced-InSAR analysis highlights active deformation in the MS. We also review the historical and instrumental seismicity affecting this region. Based on the chronology of the most recent phases and the time elapsed between the last eruptions, we conclude that the waning/extinguishment of eruptive activity shifted progressively from NW to SE, from northern Latium toward the Neapolitan area, crossing the city of Rome. Although Monti Sabatini is unaffected by the unrest indicators presently occurring at the Colli Albani, it should be regarded as a dormant volcanic district, as the time of 70 kyr elapsed since the last eruption is of the same order of the longest dormancies occurred in the past.

We provide a database of the surface ruptures produced by the 26 December 2018 Mw 4.9 earthquake that struck the eastern flank of Mt. Etna volcano in Sicily (southern Italy). Despite its relatively small magnitude, this shallow earthquake caused about 8 km of surface faulting, along the trace of the NNW-trending active Fiandaca Fault. Detailed field surveys have been performed in the epicentral area to map the ruptures and to characterize their kinematics. The surface ruptures show a dominant right-oblique sense of displacement with an average slip of about 0.09 m and a maximum value of 0.35 m. We have parsed and organized all observations in a concise database, with 932 homogeneous georeferenced records. The Fiandaca Fault is part of the complex active Timpe faults system affecting the eastern flank of Etna, and its seismic history indicates a prominent surface-faulting potential. Therefore, this database is essential for unravelling the seismotectonics of shallow earthquakes in volcanic areas, and contributes updating empirical scaling regressions that relate magnitude and extent of surface faulting., Measurement(s)coseismic surface rupture • surface rupture kinematics • surface rupture displacement • surface rupture locationTechnology Type(s)field survey • GPS navigation systemFactor Type(s)offset • strike • angle • length • latitude • longitude • elevationSample Characteristic - Environmentvolcanic fieldSample Characteristic - LocationIsland of Sicily • Mount Etna Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.11673027

The M6.3 earthquake that occurred in southern Lazio (Central Italy) in 1654 is the strongest seismic event to have occurred in the area. However, our knowledge about this earthquake is scarce and no study has been devoted to the individuation of its causative source. The main purpose of this study is putting together all of the information available for this shock to provide reliable landmarks to identify its seismic source. To this end, we present and discuss historical, hydrological, geological, and seismological data, both reviewed and newly acquired. An important, novel part of this study relies on an analysis of the coseismic hydrological changes associated with the 1654 earthquake and on the comparison of their distribution with models of the coseismic strain field induced by a number of potential seismogenic sources. We find more satisfactory results when imposing a lateral component of slip to the faults investigated. In particular, oblique left-lateral sources display a better fit between strain and hydrological signatures. Finally, the cross-analysis between the results from modeling and the other pieces of evidence collected point to the Sora fault, with its trend variability, as the probable causative source of the 1654 earthquake.

The 2016 August 24th, M w 6.0 Amatrice (Central Italy) normal faulting earthquake produced a remarkable number of Earthquake-Rotated Objects (EROs) that affected chimneys, as well as pillars and capitals on gates and walls. In this paper we present the EROs dataset, and perform some qualitative analyses to evaluate if specific geological and seismological features such as intensity, epicentral distance, potential amplification of the seismic shaking at the site, heterogeneities of the rupture on the fault and directivity effects, and peak ground accelerations, favoured the distribution of EROs observed after the earthquake. A first important outcome is that the distribution of the EROs of Amatrice 2016 mimics the general pattern of damage, and that EROs occurrence should be regarded as a diagnostic element of intensity degrees lower than those presently established by formalized scales. We also find that site factors, namely the surface geology and the local amplification, are the most significant contributors to the EROs occurrence. In addition, we find that the position respect to the fault can enhance the occurrence of local rotations. The distinctive features characterizing the 2016 EROs dataset resemble and substantiate the most important findings produced by previous studies carried out following the 2009 L’Aquila and 2012 Emilia seismic sequences, and allow to calibrate the empirical relations on the EROs distribution presented in the world Catalog of Earthquake-Rotated Objects.

On 24 August 2016, a Mw 6.0 normal faulting earthquake struck central Italy, causing about 300 fatalities and heavy damage. A geological survey collected the coseismic effects observed at the surface in order to evaluate two competing hypotheses about their nature: surface faulting versus gravitational deformation. We find that the most significant geological effect is a 5.2 km-long alignment of ground ruptures along the Mt. Vettore Fault-System. These ruptures are independent from lithology, topography, morphology and change in slope and exhibit an average dip slip displacement of ~13 cm. Geometry, kinematics and dimensional properties of this zone of deformation strongly lead us to favor the primary surface faulting hypothesis that fits well the predicted estimates from experimental scaling-law relationships. Our study provides relevant hints for surface faulting in extensional domains, contributing to implement the worldwide database of the moderate earthquakes.

Though the Calabrian arc is the most seismic area of the Italian peninsula, the overwhelming majority of M >6:5 earthquakes have occurred during the last four centuries. Conversely, the Italian seismic catalog exhibits an almost total absence of earthquakes -even moderate- magnitude earthquakes- between the eleventh and sixteenth centuries. The reason for this anomalous distribution of seismicity can be partially accounted for by the lack of historical sources caused by a paucity of local archives and by the enduring isolation of local administrations. We focused our research on moderate-magnitude earthquakes of centralnorthern Calabria between the sixteenth and eighteenth centuries and performed systematic research in many repositories, including in the Archivio Segreto Vaticano, in the state Archives of Naples, Catanzaro, Cosenza, and Potenza, and in several historic libraries. We found 15 previously unknown earthquakes for which we provide the level of shaking and the indication of the epicentral area for the first time. Also, we could definitively categorize one further event as a landslide rather than an earthquake. Finally, we found new evidence and information about four seismic events already known in the seismological literature; in particular, we provide a new intensity map and an increased magnitude (M 6.0) of the 14 July 1767 earthquake. Besides the new data on the earthquakes, we provide general clues and hints for searching useful documents to study earthquakes in the historical context of the sixteenth–eighteenth centuries.

An international team of scientists installed a novel, dense network of 48 seismic sensors on the island of Lipari to investigate the active magma system underground.

The article presents the results of the quantitative statistical analyses of the first world catalog of earthquake‐rotated objects (EROs), presented in Part I of the study (Cucci et al. , 2016). We searched for possible relations between the epicentral distance of EROs occurrence and a number of customary seismological observables, such as magnitude, intensity, focal mechanism, etc. The reliability of results is quantitatively checked by means of some suitable statistical tests. We found strong evidence of a clear log–linear dependence of the epicentral distance, to which an ERO can be observed, on the magnitude M w of the source event. We note that the probability of observing EROs near the epicentral area ( D

The Italian seismic catalog (Rovida et al., 2011) portrays a significant gap of seismicity in the Pollino Range area, the southernmost segment of the southern Apennines at the boundary with the Calabrian arc. In this region, the only significant seismic event of the instrumental era occurred in 1998 north of the Pollino Range (Mw 5.6, Fig. 1). No seismic event with intensity greater than VIII on the Mercalli–Cancani–Sieberg (MCS) scale is present in the historical records, whereas strong earthquakes occurred immediately north (1836 M 6.0; 1857 M 7.0) and south (1184 M 6.7; 1836 M 6.2) of the area (Fig. 1). However, geologic data (Bousquet, 1973; Russo and Schiattarella, 1992) have shown clear evidence of Quaternary faulting along two major normal seismogenic faults, the Pollino and the Castrovillari faults. Paleoseismological data (Michetti et al., 1997; Cinti et al., 1997, 2002) recognized the occurrence of large magnitude events during medieval times along those two faults, but no trace is left of these major events in the historical record. In the case of the Pollino area, the discrepancy between true seismic history and recorded seismic history is due to a combination of a documentary gap of the historical sources (Scionti et al., 2006) and to the low population and scarcity of settlements in the epicentral area (D’Addezio et al., 1995; Cinti et al., 1997). Furthermore, there is the sound possibility that such documentary limitation also might affect moderate (M 5–6) earthquakes, thus providing the opportunity for new assessments that could re-estimate their sizes. Noticeable recent examples of this come from Scionti et al. (2006), with the reestimation to Mw 6.2 of an earthquake that occurred 100 km southeast of the Pollino region, from Tertulliani et al. (2012) for the 1762 earthquake close to L’Aquila, and from Azzaro et al. (2007) for northeastern Sicily. We want to emphasize that there is recent growing interest in the question of reestimating the sizes of historical earthquakes (see Rong et al., 2011; Hough, 2013). Therefore, reducing the uncertainties in the locations and sizes of seismic events for areas like Pollino can be an important contribution toward a clearer picture of the seismic potential and the distribution of earthquake recurrence times that can affect the seismic hazard of a territory. The first attempts at in-depth analyses of the historical seismicity in the Pollino seismic gap date back to the first half of the 1990s (Storia Geofisica Ambiente [SGA], 1994; Valensise et al., 1994; Guidoboni and Mariotti, 1997), whereas more recent developments are by SGA (2000), Camassi and Castelli (2004), and Castelli and Camassi (2005). The seismic histories (the list of earthquakes affecting a site during historic time) of towns and villages of the area (Locati et al., 2011) do not contain earthquakes that occurred before A.D. 1600, neither local nor remote, which could have affected such localities. The oldest traces of earthquakes are associated with the 1638 M 7 event that occurred in central Calabria ∼100 km south of the Pollino area and produced damage in Castrovillari. The more ancient event documented in the study area is the 1693 earthquake, which was listed for the first time in a catalog in 2007 (Guidoboni et al., 2007). In this study, we focus on this latter event, which also appears as the strongest shock in the region and is characterized by a relative scarcity of information and few intensity datapoints. We gathered all potential primary sources of information available for the 1693 earthquake in the attempt to improve its intensity map. We also address two further issues in the reappraisal of the 1693 earthquake: (1) the temporal coincidence between 8 January 1693 Pollino earthquake and its aftershocks and 9–11 January 1693 catastrophic earthquakes of eastern Sicily, along with the consequent quest for a correct attribution of the information regarding the two seismic sequences; and (2) the occurrence in October 2012 (following a sequence of small earthquakes lasting three years) of an Mw 5.3 mainshock, which is by far the strongest event in the instrumental era in the area.

Online Material: Table of the EROs observed following the 2012 seismic events. In the past few years, the awareness that earthquake‐induced rotational effects can be significant in the near‐fault region of an earthquake, and the consequent implications in seismic engineering, has gained rotational seismology a strong recovery in the attention of the scientific community. Impulses came from direct observations as well as numerical simulations, and special volumes related to this topic have been recently published by the Bulletin of the Seismological Society of America (Lee et al. , 2009) and by the Journal of Seismology (Igel et al. , 2012). In particular, some of the most recent papers on this subject addressed the earthquake‐rotated objects (EROs hereinafter), considering the possible contribution to EROs occurrence from true rotational motion and/or translational motion (Kozak, 2006, 2009; Yang et al. , 2010; Hinzen, 2012), the geometry of the structure (Mucciarelli et al. , 2011), the clockwise/counterclockwise (CW/CCW hereinafter) sense of rotation (Yegian et al. , 1994), and the geological conditions at the site (Cucci and Tertulliani, 2011; Castellano et al. , 2012). The renewed attention to earthquake‐induced rotations allowed the collection of a significant dataset of EROs following the M w 6.3 2009 L’Aquila (Central Italy) event (see Cucci et al. , 2011 for a complete description of the dataset); this kind of data collection is a sound starting point for subsequent quantitative analyses of the data. In this paper, we present a new ![Graphic][1] dataset of EROs (available in the electronic supplement to this paper) originated by the Emilia seismic sequence, which occurred in northern Italy in 2012. The main aim of this study is to verify whether and how the distribution of the 2012 EROs is influenced by some geophysical observables (epicentral distance, intensity, directivity, lithology, etc.), in a geomorphological and seismological context completely different … [1]: /embed/inline-graphic-1.gif

Earthquake‐rotated objects (EROs) have been observed and described for centuries (e.g., Hoffmann, 1838; Mallet, 1862; Reid, 1910). Several theories about the rotating mechanisms have been developed. Kozak (2006) classified rotating effects as those caused by a deviation between the projection of the center of gravity into the contact plane and the point of strongest adhesion (Rot1) and those due to subsequent arrival of ground‐motion phases from different directions (Rot2). The EROs found in the literature include parts of buildings, such as chimneys, monuments, tombstones, and columns, often described with great care and in detail by early earthquake reports (Mallet, 1862) or still accessible (Boschi et al. , 1995). However, in most cases rotational effects are observed on vertically oriented objects such as gravestones, tall monuments, and single columns (Kozak, 2009). Although earthquake‐toppled objects (ETOs) allow the determination of minimum ground‐motion thresholds which caused the toppling (Kamai and Hatzor 2008; Hinzen, 2010, 2012), EROs and earthquake‐deformed objects (EDOs) present the chance to make a more detailed back calculation of the causative ground motion (Yegian et al. , 1994; Lee et al. , 2009; Hinzen et al. , 2010; Hough et al. , 2012). Numerous EROs were observed and documented during the 2009 L’Aquila earthquake in central Italy. Cucci and Tertulliani (2011) and Castellano et al. (2012) showed a correlation between the occurrence of EROs in the mesoseismal zone, the fault orientation, and the site conditions. Some of the simply structured and vertically oriented objects mapped by Cucci et al. (2011) and Cucci and Tertulliani (2011) offer the opportunity to use local strong‐motion records to test different hypotheses about the mechanisms that caused the rotation. A main question in this context is whether near‐field rotational components of ground motion are necessary to rotate the studied objects or whether 3D purely translational …

In this paper we present the geological effects induced by the 2012 Emilia seismic sequence in the Po Plain. Extensive liquefaction phenomena were observed over an area of ~ 1200 km2 following the 20 May, ML 5.9 and 29 May, ML 5.8 mainshocks; both occurred on about E–W trending, S dipping blind thrust faults. We collected the coseismic geological evidence through field and aerial surveys, reports from local people and Web-based survey. On the basis of their morphologic and structural characteristics, we grouped the 1362 effects surveyed into three main categories: liquefaction (485), fractures with liquefaction (768), and fractures (109). We show that the quite uneven distribution of liquefaction effects, which appear concentrated and aligned, is mostly controlled by the presence of paleo-riverbeds, out-flow channels and fans of the main rivers crossing the area; these terrains are characterised by the pervasive presence of sandy layers in the uppermost 5 m, a local feature that, along with the presence of a high water table, greatly favours liquefaction. We also find that the maximum distance of observed liquefaction from the earthquake epicentre is ~ 30 km, in agreement with the regional empirical relations available for the Italian Peninsula. Finally, we observe that the contour of the liquefaction observations has an elongated shape almost coinciding with the aftershock area, the InSAR deformation area, and the I ≥ 6 EMS area. This observation confirms the control of the earthquake source on the liquefaction distribution, and provides useful hints in the characterisation of the seismogenic source responsible for historical and pre-historical liquefactions.

Vein networks affect the hydrothermal systems of many volcanoes, and variations in their arrangement may precede hydrothermal and volcanic eruptions. However, the long-term evolution of vein networks is often unknown because data are lacking. We analyze two gypsum-filled vein networks affecting the hydrothermal field of the active Lipari volcanic Island (Italy) to reconstruct the dynamics of the hydrothermal processes. The older network (E1) consists of sub-vertical, N-S striking veins; the younger network (E2) consists of veins without a preferred strike and dip. E2 veins have larger aperture/length, fracture density, dilatancy, and finite extension than E1. The fluid overpressure of E2 is larger than that of E1 veins, whereas the hydraulic conductance is lower. The larger number of fracture intersections in E2 slows down the fluid movement, and favors fluid interference effects and pressurization. Depths of the E1 and E2 hydrothermal sources are 0.8 km and 4.6 km, respectively. The decrease in the fluid flux, depth of the hydrothermal source, and the pressurization increase in E2 are likely associated to a magma reservoir. The decrease of fluid discharge in hydrothermal fields may reflect pressurization at depth potentially preceding hydrothermal explosions. This has significant implications for the long-term monitoring strategy of volcanoes.

The effort for reducing the uncertainties in the location and size of historical earthquakes, even moderate-size ones, is not a peripheral issue, as it plays a major role in the distribution of earthquake recurrence times that can affect the maps of seismic hazard of a territory. The L’Aquila area (Abruzzo, Central Italy) struck by the 6 April 2009 Mw 6.3 seismic event is a typical example of an earthquake-prone region, the location of which historical seismicity needs to be better located. Thanks to a large body of geological, seismological, and geodetic evidence, the deep source of the 2009 mainshock has been imaged as a ~15-km-long, northwest-trending, southwest-dipping, almost-pure normal fault coinciding with the Paganica fault system at the surface (Fig. 1). Conversely, so far, very few papers have addressed the issue of reconstructing the seismic history of the Paganica fault, charting the relationships between this fault and the adjacent ones, and finding out the causative source for each of the earthquakes listed in the Italian earthquake catalog (CPTI Working Group, 2004; Rovida et al., 2011). In particular, the 1461 M 6.4 and the 1762 M 6.0 earthquakes (Fig. 1) took place in the same general area and display a comparable magnitude with that of the 2009 earthquake. According to recently provided paleoseismological data (Cinti et al., 2011), the shock of the 1461 earthquake was the penultimate event that ruptured the Paganica fault. The case of the 1762 earthquake was more open to debate: Tertulliani et al. (2009) suggested that it could have had the same fault source as that of the 2009 shock (west of the catalog epicenter) on account of some similarities in the distribution of the maximum intensities and in the temporal evolution of the 1762 and 2009 sequences. At the same time, however, Tertulliani et al. (2009) were aware of, and cautioned against, the very short recurrence interval implied by their hypothesis. The issue of the too-short recurrence interval, along with some observations on the too-low throw rate measured across the Paganica fault, induced Roberts et al. (2010) to invoke the role of other neighboring sources and to propose for the 1762 shock an alternative location some 10 km east-southeast of the epicenter adopted by the catalog. Such a variance of opinions concerning the epicentral location of the 1762 earthquake is explained by the scantiness of the data set on which investigations must rely and which consists of the shaking intensities at three localities only. As Di Bucci et al. (2011) pointed out, such a data set made it impossible to associate the 1762 event to any fault “beyond mere speculation”. We are left from this stark and somewhat frustrating consideration to systematically gather all potential primary sources of information available for the 1762 earthquake in the area to attempt to improve its intensity map and to compare it with the 2009 one. In the following, we will (1) set out the evidence newly collected from archives in L’Aquila and Naples and from other repositories of contemporary sources; (2) explain the rationale that allowed us to turn demographic and historical information into data sensitive to macroseismic analyses; (3) show the new intensity map for the 1762 earthquake and discuss its main differences from the previous intensity data sets (Boschi et al., 2000 and the most recent versions of the Italian macroseismic database, i.e., Stucchi et al., 2007; Locati and DBMI Working Group, 2009; Locati et al., 2011); (4) provide a more accurate location and propose new source parameters for the event; and (5) discuss the constraints on its epicenter location and source parameters with the possible seismotectonic implications.

The 2009 M w 6.3 L’Aquila earthquake produced an impressive number of rotational effects on vertically organized objects such as chimneys, pillars, capitals, and gravestones. We present a dataset of such effects that consists of 105 observations at 37 different sites and represents a compendium of earthquake-induced instances of rotational effects that is unprecedented in recent times. We find that the absolute majority of the reported effects were observed in the epicentral zone and that most of the observations are located where the Mercalli–Cancani–Sieberg intensity is between 7 and 8–9. The evident asymmetry in the distribution of the rotational effects resembles the southeastward directivity of the macroseismic effects and highlights a significant convergence between rotations and damage. Finally, we perform some qualitative analyses to recognize and evaluate which geological and seismological parameters can be significant contributors to local rotations. We find that surface geology and amplification of the seismic motion at each reported location strongly influence the occurrence and the nature of the earthquake-induced rotational effects. Conversely, the contribution of the pattern of slip distribution on the fault plane plays only a secondary role in enhancing the rotational motion at each site.

Terra Nova, 22, 378–389, 2010 Abstract The elevation of the Capo Vaticano coastal terraces (Tyrrhenian coast, central Calabria) is the result of a combination of regional uplift and repeated coseismic displacement. We subtract the regional uplift from the total uplift (maximum average uplift rates: 0.81–0.97 mm a−1 since c. 0.7 Ma) and obtain the residual fault-related displacement. Then, we model the residual displacement to provide constraints on the location and geometry of the seismogenic source of the 1905 M7 earthquake, the strongest – and still poorly understood – earthquake of the instrumental era in this area. We try four different potential sources for the dislocation modelling and find that (1) three sources are not compatible with the displacement observed along the terraces and (2) the only source consistent with the local deformation is the 100°-striking Coccorino Fault. We calculate average long-term vertical slip rates of 0.2–0.3 mm a−1 on the Coccorino Fault and estimate an average recurrence time of ∼one millennium for a 1905-type earthquake.

On 6 April 2009 an Mw = 6.3, Imax = 9–10 earthquake struck the Abruzzi region of Central Italy (http://portale.ingv.it/highlights/view?set_language=en). We find similarities in some peculiar characteristics of the 2009 sequence and some historical events that occurred in the area, in particular in 1461 and 1762. We observed strong analogies in the distribution of the intensities and in the areas of the strongest effects produced by these shocks, as well as in the temporal evolution of the events. The 2009 quake severely devastated the town of L’Aquila (~ 73,000 inhabitants) and tens of villages located in the middle Aterno Valley (hereinafter MAV, see Figure 1). One month after the event, its social impact was not yet fully known but was certainly burdensome: 308 casualties, 47% of homes damaged in the epicentral area, 20% of those were heavily damaged (with an even worse situation in downtown L’Aquila), and about 40,000 people left homeless. Although the magnitude of the event was not among the largest to have occurred in the Apennines, the Abruzzi earthquake can be considered one of the most disastrous of the last century. The effects of the shaking were recorded not only in the epicentral zone but also in distant areas (e.g., as far as Rome, some 90 km from the epicenter, where it produced light damage) and heavily affected the cultural and socio-economic fabric of a wide region characterized by high seismic risk.

This paper describes the variation of the human perception of earthquakes under the peculiar condition of seismic sequence occurrence. To this aim, we chose and have analyzed four seismic sequences that reflect the most common models of seismicity occurrence in the Italian territory. Our data always refer to the epicentral area, so that the contribution of the epicentral distance to the earthquake sensitiveness is considered constant. To search for recurrent behavior of people in the perception of earthquakes, we crossed seismological data to sensitivity data coming from the archives of the Italian Civil Protection. In each sequence, we individuate a number of “indicators”, such as the rate between felt and not-felt events and the minimum magnitude for which 100% of the events are felt. Such indicators are proportional to the energy released by the sequence and can be particularly affected by the time protraction of the sequence, and/or by the different familiarity with the seismic phenomenon, and/or by the intensity of the emotional impact of a seismic crisis. The observed trends of sensitiveness show a significant variation of the people perceptivity within the sequence development. From the analysis of the dataset, one can distinguish the variation of perceptivity due to emotional factors from those due to physical factors. An important observation, which is confirmed by a statistical analysis, is that the source depth does not affect the perceptiveness of earthquakes. Finally, we find important differences between on-sequence and off-sequence human perceptiveness that are connected with the different levels of alert.

In May–June 2012, a seismic sequence struck a broad area of the Emilia-Romagna region in Northern Italy. The sequence included two mainshocks (on 20th May a ML 5.9 and on 29th May a ML 5.8). The whole aftershocks area extended in an E–W direction for more than 50 km, and included five ML ≥5.0 and more than 1,800 ML >1.5 earthquakes. Instrumental and historical local seismic records show low seismicity rate, the closest and more relevant historical earthquake being the 1570 A.D. earthquake that hit Ferrara. Widespread secondary geological effects were produced by the 2012 Emilia sequence and are mainly related to liquefaction phenomena. A total of more than 1,300 geologic coseismic effects were identified over more than 1,200 km2. We present some preliminary results concerning the study of the liquefactions occurred during the 2012 Emilia seismic sequence with particular emphasis on: (a) the definition of the areas most prone to liquefaction, (b) the identification and characterization of potential paleoliquefaction events. To identify the zones with high, medium or low liquefaction hazard, we show our quantitative approach defined to obtain a GIS based detailed analysis of the geometric relationships between the observed liquefactions and some peculiar geomorphic features of the 2012 epicentral. Differently, for recognition and characterization of paleoliquefaction events we adopted a multidisciplinary approach involving sedimentology, mineralogy and magnetic properties of the 2012 liquefied sands together with geophysical profiling, coring and dating.

In May 2002, Stromboli–one of the two active volcanoes in the Aeolian Islands (southern Tyrrhenian sea)–entered a new phase of explosive activity, initially characterized by gas and ash emission from the summit craters. On 30 December 2002, a massive submarine landslide, followed by a subaerial one from the elevation of about 650 m above sea level (a.s.l.), detached from the submerged part of the northwest slope of Stromboli island producing a tsunami. This huge mass movement was recorded by the INGV seismic stations installed, respectively, at Stromboli and Panarea. In the following days, a working group of INGV researchers and technicians was organized in order to perform a field survey of the tsunami effects in the near-field—including all the Aeolian Islands. Meanwhile, a survey in the far-field was planned, along the coastline of Campania and Sicily, where the effects of the 30 December tsunami were observed but not directly quantified. Visible material effects of the 30 December tsunami could be observed only along the northeast coast of Stromboli island, inundated by the wave, with run-up heights locally up to several meters. Many buildings were severely damaged. On the other Aeolian Islands and in the far-field, the effects of the sea wave were documented only through eyewitness accounts. To ensure a coherent collection of these accounts, a standard interview form, based on the advice of the Intergovernmental Oceanographic Commission (IOC), was used. A databank of all observations, measurements, interview forms and photographs was compiled in order to provide a useful base to test computer simulations, hazard analyses and damage scenarios. Additional information was also made available at the EMERGEO link of INGV web pages http://www.ingv.it/emergeo and http://www.ov.ingv.it .

SUMMARY Our study area is a ca 50 km long section of the central-southern Apennines tectonic belt that includes the Pergola–Melandro basin (PM) and the Agri valley (AV). This region is located between the areas affected by the 1980 Ms= 6.9 Irpinia and the 1857 M= 7.0 val d'Agri earthquakes and is characterized by rare historical events and very low and sparse background seismicity. In this study we provide new seismological and geophysical information to identify the characteristics of the seismotectonics in the area as the prevailing faulting mechanism and the fit of local to regional stress field. These data concern focal mechanisms from waveform modelling and P-wave polarities, analyses of borehole breakouts and detailed investigation of two seismic sequences. All the data cover a significantly broad range of magnitudes and depths and suggest that no important local variation in stress orientation seems to affect this area, which shows a NE–SW direction of extension consistent with that regionally observed in southern Italy. Such local homogeneity in the stress field pattern is peculiar to the study area; the variations of orientation and/or type of stress observed in the northern Apennines, or less than only 100 km toward the northwest within the same tectonic belt, are absent here. Furthermore, there is a suggestion for a northeastward sense of dip of the seismogenic faults in the region, an interesting constraint to the characterization of seismic sources.

The Pollino Range area represents the most prominent gap in seismicity within the southern Apennines. Geomorphic and trenching investigations along the Castrovillari fault indicate that this normal fault is a major seismogenic fault within the southern part of this gap. At least four surface-faulting earthquakes have occurred on this fault since late Pleistocene age. Radiocarbon dating coupled with historical consideration set the time of the most recent earthquake as most likely to be between 530 A.D. and 900 A.D., with the possible widest interval of 530–1100 A.D. No evidence for this event has been found in the historical records, although its age interval falls within the time spanned by the seismic catalogues. Slip per event ranges between 0.5 and 1.6 m, with a minimum rupture length of 13 km. These values suggest a M 6.5–7.0 for the paleoearthquakes. The minimum long-term vertical slip rate obtained from displaced geomorphic features is of 0.2–0.5 mm/yr. A vertical slip-rate of about 1 mm/yr is also inferred from trenching data. The inter-event interval obtained from trench data ranges between 940 and 7760 years (with the young part of the interval possibly more representative; roughly 940–3000 years). The time elapsed since the most recent earthquake ranges between a minimum of 900–1100 and a maximum of 1470 years. The seismic behavior of this fault appears to be consistent with that of other major seismogenic faults of the central-southern Apennines. The Pollino case highlights the fact that geological investigations represent a potentially useful technique to characterize the seismic hazard of ‘silent’ areas for which adequate historical and seismological data record are not available.

A field survey performed during the 1997 Umbria-Marche earthquake sequence led us to recognize ground and pavement ruptures associated with the three largest shocks (Mw ≥ 5.7). The ruptures are concentrated in narrow bands that, in part, are on and near previously mapped high-angle normal faults. The geometry of the ground deformation is consistent with the NE-trending extension indicated by CMT focal solutions of the mainshocks. The distribution of aftershocks suggests that the three mainshocks occurred on ∼40° SW-dipping normal faults. Geological investigations, modelling of expected coseismic elevation changes, and seismic data, suggest that the surface deformation is not the direct result of primary rupture of faults at depth.

The setting of a flight of marine terraces along a 65-km-long section of the Ionian coast of northern Calabria is the result of the interaction between interglacial sea levels, regional uplift, and local fault-related elevation changes. Seven terraces with corresponding palaeoshoreline angles at elevations ranging from 12 m to ∼420 m were recognised by aerial photo interpretation and field surveying. The terraces were correlated to the oxygen isotope stages 1, 5a, 5c, 5e, 7, 9, 15, which correspond to the 7, 81, 102, 124, 215, 330 and ∼600 ka highstands of the palaeosea-level curve. The ∼600-ka-long regional ascent of the terraces took place at an average uplift rate of 0.67 mm/yr; this value slightly but progressively increases southward along the coastline. The elevation of the strandlines is related to the activity of tectonic structures. Three cases were analysed, allowing us: (1) to recognise the height anomalies of the terraces on the Sibari plain as the result of cumulated coseismic deformation caused by the normal Castrovillari fault, and on this basis calculate a minimum slip rate and a mean recurrence time for a single event of deformation; (2) to exclude the presence of significant vertical deformations and consequently activity on the easternmost section of the normal Pollino fault; and (3) to hypothesise the presence of an hitherto unknown active fault responsible for the strong vertical displacements of the flight of terraces near the river Avena. Finally, we find the ratio of the rate of regional uplift to the average rates of local tectonic deformation to be 2 to 3 : 1.

In our recent article (Cucci et al. , 2016), we presented the world catalog of earthquake‐rotated …

On May 20, 2012, a Ml 5.9 seismic event hit the Emilia Po Plain, triggering intense earthquake activity along a broad area of the Po Plain across the provinces of Modena, Ferrara, Rovigo and Mantova (Figure 1). Nine days later, on May 29, 2012, a Ml 5.8 event occurred roughly 10 km to the SW of the first main shock. These events caused widespread damage and resulted in 26 victims. The aftershock area extended over more than 50 km and was elongated in the WNW-ESE direction, and it included five major aftershocks with 5.1 ≤Ml ≤5.3, and more than 2000 minor events (Figure 1). In general, the seismic sequence was confined to the upper 10 km of the crust. Minor seismicity with depths ranging from 10 km to 30 km extended towards the southern sector of the epicentral area (ISIDe, http://iside.rm.ingv.it/). […]

A devastating earthquake was predicted to hit Rome on May 11, 2011. This prediction was never officially released, but it grew on the internet and was amplified by the media. It was erroneously ascribed to Raffaele Bendandi, an Italian self-taught natural scientist who studied planetary motions and related them to earthquakes. Indeed, around May 11, 2011, there was a planetary alignment, and this fed the credibility of the earthquake prediction. During the months preceding May 2011, the Istituto Nazionale di Geofisica e Vulcanologia (INGV) was overwhelmed with requests for information about this prediction, by the inhabitants of Rome and by tourists. Given the echo of this earthquake prediction, on May 11, 2011, the INGV decided to organize an Open Day at its headquarters in Rome, to inform the public about Italian seismicity and earthquake physics. The Open Day was preceded by a press conference two days before, to talk with journalists about this prediction, and to present the Open Day. During this ‘Day’, 13 new videos were also posted on our YouTube/INGVterremoti channel to explain earthquake processes and hazards, and to provide periodic updates on seismicity in Italy from the seismicity monitoring room. On May 11, 2011, the INGV headquarters was peacefully invaded by over 3,000 visitors, from 10:00 am to 9:00 pm: families, students with and without teachers, civil protection groups, and many journalists. This initiative that was built up in a few weeks has had very large feedback, and was a great opportunity to talk with journalists and people about earthquake prediction, and more in general about the seismic risk in Italy.

This paper presents the study of some liquefaction features occurred near the Fossa village due to the April 6, 2009, Mw 6.3 L’Aquila earthquake (Central Italy). Our investigation is based on trenching and coring campaigns as well as sedimentological analyses and datings. The geometrical elements of the sand volcanoes on the surface, of the dike used to rise up and of the probable sandy source at depth are presented. A sandy pockets level found at less than 1 m of depth, interpreted as possible evidence for a paleo-liquefaction event is discussed. Sedimentologic and morphoscopic analyses both provided the necessary elements and parameters to link the ca. 4 m deep sandy layers to the 2009 sand blows on the ground surface as well as to the paleo-liquefaction layer and defined the main characteristics of the deposits sealing the sands that experience liquefaction at depth. Finally a tentative correlation between the paleo-liquefaction layer and the 1461 AD or the 1703 AD local earthquakes is suggested based on the available age constraints.

[1] We performed paleoseismological investigations at four sites across the normal Paganica fault (PF) (source of the 2009 Mw 6.3 L'Aquila earthquake), with the goal of reconstructing the rupture history and of contributing to the evaluation of the maximum event expected along the PF. We recognized five distinct surface faulting earthquakes (including the 2009) in the trenches. The age of the penultimate event is consistent with the 1461 earthquake; the third event back occurred around 1000 AD. The two oldest events have larger uncertainties and occurred in the interval 760 BC–670 AD and 2900–760 BC, respectively. The along-strike vertical displacement for each paleoevent has a limited variability consistently with the fairly homogeneous slip observed in 2009 along the northern part of the rupture. Conversely, the throws change between distinct events and range between 0.15 m in 2009 (maximum estimate) and close to 0.4 (lower bound estimate) in earlier events. These paleorecords and the high fault escarpments imply that earthquakes larger than 2009 occurred on the PF, with implications for the level of hazard. Recurrence intervals also reflect a change with time, the average interval before ∼1000 AD is longer compared to that after this date. Two events occurred in the 2000–4000 years preceding ∼1000 AD, while three events occurred since ∼1000 AD. The age uncertainties affecting the interpreted events prevent the evaluation of a unique value for interevent interval; the older events appear closely spaced in time or far apart depending on the upper or lower boundary of the age interval. We tentatively assign an average interevent time of ∼500 years for the three youngest events, whereas the time elapsed between the previous ones could be larger, in the order of 1000–2000 years. We calculate a late Pleistocene dip-slip rate for the PF of 0.2–0.4 mm/yr, consistent with 0.25–0.5 mm/yr for the early Pleistocene. Using age and throw of individual events, we calculate a similar late Holocene average dip-slip rate of ∼0.3–0.4 mm/yr. This suggests that the portion of the PF where the 2009 continuous surface faulting occurred has fairly a constant average slip release since late Pleistocene. Finally, we discuss different rupture scenarios and alternative models of occurrence compatible with our data and their variability.

After the February 23, 1991 event, localized northwest of Cassino, some phenomena were noted (strong rumbles, shakes, etc.) that frightened people and alarmed the local authorities. To identify the possible causes of these phenoena, a geological and seismic survey was carried out, with particular attention to the hydrogeology of the area. Two seismographic stations were also set up. The stations were removed when the phenomena ceased.

Seismic data users and people managing a sesimic network are both interested in the potentiality of the data, with the difference that the former look at stability, the second at improvements. In this work we measure the performances of the Italian Telemetered Seismic Network in 1985-2002 by defining basic significant parameters and studying their evolution during the years. Then, we deal with the geological methods used to characterise or to plan a seismic station deployment in a few cases. Last, we define the gain of the network as the percentage of located earthquakes with respect to the total recorded earthquakes. By analysing the distribution of non-located ("missed") earthquakes, we suggest possible actions to take in order to increase the gain. Results show that completeness magnitude is 2.4 in the average over the analysed period, and it can be as low as 2.2 when we consider non-located earthquakes as well. Parameters such as the distance between an earthquake and the closest station, and the RMS location decrease with time, reflecting improvements in the location quality. Methods for geologic and seismological characterisation of a possible station site also proved to be effective. Finally, we represent the number of missed earthquakes at each station, showing that nine stations control more that 50% of all missed earthquakes, and suggesting areas in Italy where the network might be easily improved., Comment: 17 pages, 1 table, 11 figures. Submitted to Annals of Geophysics

Historical accounts handed down the legend of the ancient Sybaris, defeated and submerged by the Crotoniates who diverted the River Crati on the town. This paper deals with the reconstruction of the Holocene evolution of the Sybaris Plain, through a number of geological and geomorphological observations. In particular, I found i) ?1 m/yr horizontal coastal progradation rate since Greek times (2.4 kyr BP), possibly since Neolithic (7.0 kyr BP), mainly originated by active alluvial deposition and subordinately by regional uplift; ii) evidence of striking modifications in the surface hydrography of the plain during the last 2.5 kyr, with repeated fluvial captures of the Crati and Coscile rivers testified by ancient historians and geographers, recent maps and archeological accounts. In addition, datings and archeological information from 7 sites in the plain provided iii) ?0.6 mm/yr mean uplift rate during the past 11.2 kyr, that confirms the substantial continuity of this regional process with upper Pleistocene; iv) local, high value of subsidence (0.5÷2.0 mm/yr) affecting the Sybaris main archeological area. Subsidence is not recorded before 4000 years BP and is caused by deposition of fine, highly compressible sediments at the transition between marine and continental environment; v) no evidence of a fault-induced contribution to the subsidence, whilst there is the grounded possibility that man-induced subsidence prevailed in the last century; vi) widespread active continental deposition in the area. Local rates of deposition are relatively lower (1.5 mm/yr) at sites where subsidence is not observed, and range between 2.5 mm/yr and 3.5 mm/yr in the main archeological area. There is also evidence of a clear decrease of the sedimentation following the Mid-Holocene flex of the fast trend of sea level rise. These data suggest that the Holocene evolution of the Sybaris Plain is due to the progressive eastward migration of the land-sea boundary, probably active since the Mid-Holocene (?7.0 ka). Repeated floodings, regional uplift and relative sea-level changes produced the eastward expansion of the plain, subsidence locally slowed it down. Therefore, geology first allowed the creation of Sybaris, then caused its destruction.