The 1997 Umbria-Marche earthquakes (Italy): relation between the surface tectonic breaks and the area of deformation

We classified the most outstanding rupturesof the 1997 Umbria-Marche seismic sequence assecondary tectonic effects that occur within the zoneof deformation induced by the deep displacement on theseismogenic structure. The trend of the surfacedeformation is homogeneous within the entire area ofinterest and consistent with NE-oriented extensionevidenced by CMT focal solutions of the three mainshocks. We extrapolate the discontinuous sites ofbreak measurements and suggest that the localdeformation concentrates along four narrow bands.Location and direction of these bands are locallycontrolled by pre-existing structures. The comparisonbetween our data with the seismological data – such asmain rupture planes and spatial aftershockdistribution – highlights that three bands mark partof the boundaries of the NW-SE elongated aftershocksarea and the fourth occurs where this area is widest.Moreover, the analysis of the structural setting ofthe area suggests that N-S shear zones have stronglycontrolled the extension of the main rupture segmentsand the aftershock distribution. The surface rupturesare located within the area of coseismic deformationresulting from DInSAR data; we propose that theyrepresent the localized response to the verticalground deformation of the area. Finally, we discussthe contribution of the pattern of the 1997 surfacebreaks to the characterization of the seismogenicsource.     

The 1627 Gargano earthquake (Southern Italy): Identification and characterization of the causative fault

We present the results of a study of the subsurface tectonic features of the Basso Molise, Western Gargano and Northern Capitanata regions (Southern Italy) aimed at the identification of the source of the disastrous 1627 Gargano earthquake. In the maximum-damage area of this earthquake we have recognised a normal fault, here called the Apricena Fault, which has been identified as the fault that caused the seismic event. The Apricena Fault, striking WNW-ESE and dipping towards SSW, extends in the subsurface for about 30 kilometres from Serracapriola to Santa Maria di Stignano cutting through the whole Quaternary sequence. Other important tectonic structures trending WNW-ESE recognized in the area belong to an inactive Pleistocene strike-slip-fault system that is linked to the Mattinata Fault and to its offshore continuation in the Gondola-Grifone structural high. The Mattinata Fault and the Gondola-Grifone High form a quite complex structural feature whose kinematic behaviour is still matter of debate in the regional geological literature. NW-SE structural features recognized in the area are extensional faults whose activity was probably related to the late flexure-hinge retreat of the Adria plate margin during the Late Pliocene-Early Pleistocene eastward migration of the thrust belt-foredeep-foreland system.     

Seismic hazard in southern Calabria (Italy) based on the analysis of a synthetic earthquake catalog

The application of a newly developed physics-based earthquake simulator to the active faults inferred by aeromagnetism in southern Calabria has produced a synthetic catalog lasting 100 ky including more than 18,000 earthquakes of magnitude ≥?4.0. This catalog exhibits temporal, spatial and magnitude features, which resemble those of the observed seismicity. As an example of the potential use of synthetic catalogs, a map of the peak ground acceleration (PGA) for a given exceedance probability on the territory under investigation has been produced by means of a simple attenuation law applied to all the events reported in the synthetic catalog. This map was compared with the existing hazard map that is presently used in the national seismic building regulations. The comparison supports a strong similarity of our results with the values given in the present Italian seismic building code, despite the latter being based on a different methodology. The same similarity cannot be recognized for the comparison of our present study with the results obtained from a previous study based on our same methodology but with a different geological model.     

Organic pollutants (PAHs, PCBs) in sediments from the Mar Piccolo in Taranto (Ionian Sea, Southern Italy)

Polychlorinated biphenyls (PCBs) and 17 parent polycyclic aromatic hydrocarbons (PAHs) were determined in surface sediments from nine stations in the Mar Piccolo of Taranto (Ionian Sea, Southern Italy). Total PAH concentrations ranged from 380 to 12,750 microg/kg d.w., while total PCB levels ranged from 2 to 1684 microg/kg d.w.; this values were higher than those found in others marine coastal areas of the Mediterranean Sea. For PAHs, low molecular weight/high molecular weight, phenanthrene/anthracene and fluoranthene/pyrene ratio were used for discriminating between pyrolitic and petroleum origin. Results showed that PAHs were mainly of pyrolitic origin. PCB and PAH levels in sediments were compared with Sediments Quality Guidelines (ERM-ERL, TEL-PEL indexes) for evaluation probable toxic effects on marine organism. Finally, ERM and PEL quotients were used to evaluate the degree to which chemicals exceed guidelines. Results suggest an ecotoxicological risk for benthic organisms mainly in the first inlet, where high concentrations of PCBs were found in sediments influenced by harbour activities.     

Organic pollutants (PAHs,PCBs) in sediments from the Mar Piccolo in Taranto (Ionian Sea,Southern Italy)

Polychlorinated biphenyls (PCBs) and 17 parent polycyclic aromatic hydrocarbons (PAHs) were determined in surface sediments from nine stations in the Mar Piccolo of Taranto (Ionian Sea, Southern Italy). Total PAH concentrations ranged from 380 to 12,750 μg/kg d.w., while total PCB levels ranged from 2 to 1684 μg/kg d.w.; this values were higher than those found in others marine coastal areas of the Mediterranean Sea. For PAHs, low molecular weight/high molecular weight, phenanthrene/anthracene and fluoranthene/pyrene ratio were used for discriminating between pyrolitic and petroleum origin. Results showed that PAHs were mainly of pyrolitic origin. PCB and PAH levels in sediments were compared with Sediments Quality Guidelines (ERM–ERL, TEL–PEL indexes) for evaluation probable toxic effects on marine organism. Finally, ERM and PEL quotients were used to evaluate the degree to which chemicals exceed guidelines. Results suggest an ecotoxicological risk for benthic organisms mainly in the first inlet, where high concentrations of PCBs were found in sediments influenced by harbour activities.     

Geochemical signatures of large active faults: The example of the 5 February 1783, Calabrian earthquake (southern Italy)

Five large earthquakes shook southern Calabria in February–March 1783. We focused on the first shock (M_e 6.9), which occurred on 5 February in the Gioia Tauro Plain. Most investigators attribute the event to a W-dipping, high-angle fault running at the base of the Aspromonte crystalline bedrock on the ESE side of the Plain (Aspromonte Fault). Other workers contend that the earthquake was generated by an E-dipping, low-angle blind fault (Gioia Tauro Fault) similar to the adjacent Messina Straits Fault. In 1999–2000 we carried out four geochemical surveys in the Gioia Tauro Plain with the aim of contributing to this debate with an independent line of evidence. We sampled 240 groundwater sites and measured a suite of in-situ physical and chemical parameters. Our goal was to gain new insight into the seismogenic source by identifying geochemical anomalies associated with the deepening of the hydrological circuits due to the presence of enhanced faulting/fracturing. The deep-fluid signatures are mainly represented by temperature, salinity, total carbon and radon anomalies. We identified three zones of dominant deep fluid discharge: the Nicotera-Galatro area (along the Nicotera-Galatro portion of the NW-trending Nicotera-Gioiosa Jonica lineament), a small NW-SE trending area between Gioia Tauro and Seminara, and the coastline between Rosarno and Palmi. This latter sector locates just above the upper edge of the hypothesised Gioia Tauro Fault. Most of the geochemical anomalies are recorded around Rosarno, at the intersection between the Gioia Tauro Fault and the Nicotera-Gioiosa Jonica lineament. In contrast, no evidence of groundwater deepening and active fracturing was found along the Aspromonte Fault. Based on our new findings we updated the concepts of Geochemically Active Fault Zone and Geochemical Interaction Fault Zone in view of the modern understanding of the hydro-mechanical properties of fault zones and the faulting mechanisms promoting fracture permeability in the crust.     

A geological model for the Colfiorito earthquakes (September-October 1997, central Italy)

In this study, surface and subsurface geologicaldata are integrated with seismological data in orderto reconstruct a structural model for theSeptember-October 1997 Colfiorito earthquakes. Theseismic sequence is mainly controlled by two majorSW-dipping normal faults outcropping in the area (M.Pennino-M. Prefoglio and M.Civitella-Preci faults).The activated faults detach, at depth, on a commoneast-dipping low-angle normal fault, the AltotiberinaFault (AF). The AF is interpreted as the base of anactive hangingwall block which is stretching towardNE. The decrease in maximum depth of the earthquakefoci from the Colfiorito area (about 8 km) to theSellano area (about 6 km), suggested by the available seismological data, could be related to the eastward-deepening geometry of the AFdetachment. The seismic fault planes, inferred fromfocal mechanisms and aftershock distributions, arecharacterised by a moderate dip (average 40^°)toward SW, which appears to be independent from thepresence of pre-existing thrust planes.     

Geological constraints for earthquake faulting studies in the Colfiorito area (central Italy)

On September 26, 1997, at 00.33 h(GMT), a Mw 5.7 earthquake occurred in the axial zone of theUmbria-Marche Apennines of central Italy, in the Colfiorito basin area. At09.40 h (GMT), a M_w 6.0 earthquake again struck the area withinthe Colfiorito basin, a major intramontane basin filled with Quaternarycontinental deposits. The two main shocks, and the associated aftershockswere within a roughly NNW-SSE trending zone of largest damage (Imax10), in which ground deformation has been observed. Along this trend,Cello et al. (1997a) had mapped a few capable faults, showingtranstensional to pure extensional kinematics. Field inspection of themapped faults, carried out after the main shocks, revealed that some ofthem were locally reactivated (for lengths of several hundreds metres andsurface slip in the range of 2–8 cm) during the September 26, 1997earthquakes.     

Complex basin development in a wrench-dominated back-arc area: Tectonic evolution of the Crati Basin,Calabria, Italy

Field data and seismic reflection profiles of various resolutions, calibrated by deep well logs, have been used to unravel the tectonic evolution of the Crati Basin (southern Italy). The study area is located in the northern portion of the Calabrian Arc, a well-developed arc-shaped feature of the circum-Mediterranean belts, consisting of a series of ophiolite-bearing tectonic units and overlying basement nappes. NW–SE oriented left-lateral strike-slip faults exerted a major control on the tectonic evolution of northern-central Calabria, from Middle Miocene to Lower Pleistocene times. Such faults, arranged in an en-échelon geometry and dissecting the pre-existing Late Oligocene–Early Miocene orogenic belt, led to a structural setting including major N-S striking synforms – as the offshore Paola Basin and the Crati Basin are interpreted based on our results – separated by a broad antiformal ridge. Since the Middle Pleistocene, both E- and W-dipping normal faults developed in the southernmost sector of the Crati Basin, probably as a consequence of both uplift of the orogenic edifice and Tyrrhenian back-arc extension. The pre-existing regional strike-slip faults became inactive in this sector of the belt. However, working as persistent barriers, it is envisaged here that they inhibited the southern propagation of the newly formed normal faults, which therefore propagated towards the north. A minimum value of cumulative displacement of ca. 600 m has been unraveled for the central sector of the Crati Basin since Middle Pleistocene times. This yields a vertical strain rate of ca. 0.9 mm/y during the last 700 ka.     

The earthquake of 6 September 2002 and the seismic history of Palermo (Northern Sicily,Italy): Implications for the seismic hazard assessment of the city

On September 6, 2002, a M_L = 5.6 earthquake, occurring some tens of kilometres offshore from the Northern Sicilian coast (Southern Tyrrhenian Sea), slightly damaged the city of Palermo and surroundings (degree 6 in the European Macroseismic Scale 1998). The macroseismic investigation of the shock and a detailed study of effects of the main earthquakes which affected Palermo in the past have been performed in order to evaluate the seismic response of the city. Moreover, the comparison of the recent event, which is instrumentally constrained, with historical earthquakes allows us to infer new insights on the seismogenic sources of the area, that seem located offshore in the Tyrrhenian sea.In the last 500 years, Palermo has never been completely destroyed but has suffered effects estimated between intensities 6 and 8 EMS-98 many times (1693, 1726, 1751, 1823, 1940, 1968, 2002). The damage scenarios of the analysed events have shown that damage distribution is strongly conditioned by soil response in the different parts of the city and by a high building vulnerability, mainly in the historical centre and in the south-eastern zone of the modern city. As a matter of fact, Palermo has always suffered greater effects than those reported for other nearby localities. The hazard assessment obtained using observed site intensities has shown that the probability of occurrence for intensity 8 (the strongest intensity observed in Palermo) exceeds 99% for 550 years, while the estimated mean return period is 152 ± 40 years. These results, in connection with building vulnerability due to the urban expansion before the introduction of seismic code, suggest that the city is exposed to a relatively high seismic risk.This paper has not been submitted elsewhere in identical or similar form, nor will it be during the first 3 months after its submission to Journal of Seismology.     

Minimum 1-D velocity model in Southeastern Sicily (Italy) from local earthquake data: an improvement in location accuracy

The monitoring of seismic activity inSoutheastern Sicily (Italy) has beenrecently improved by a digital seismicnetwork. This effort has produced ahomogeneous and complete dataset which weused to define a reference 1-D velocitymodel. We have inverted P- and S-wavearrival times from 51 selected localearthquakes by using several initialvelocity and layer thickness models. Then,the range of possible velocity modelsobtained was tested with earthquakelocations to select the best velocitymodel. Improvements in location accuracy byusing the Minimum 1-D velocity model, withrespect to the locations obtained by usingthe routine velocity model, were evidencedfrom the reduced residuals, the smallerestimated location errors, and theincreased tendency of foci to cluster. Thedistribution of relocated hypocentersconfirmed the lack of seismic activity inthe central part of the area.     

Real time test of the long-range aftershock algorithm as a tool for mid-term earthquake prediction in Southern California

Result of the algorithm of earthquake prediction, published in 1982, is examined in this paper. The algorithm is based on the hypothesis of long-range interaction between strong and moderate earthquakes in a region. It has been applied to the prediction of earthquakes withM6.4 in Southern California for the time interval 1932–1979. The retrospective results were as follows: 9 out of 10 strong earthquakes were predicted with average spatial accuracy of 58 km and average delay time (the time interval between a strong earthquake and its best precursor) 9.4 years varying from 0.8 to 27.9 years. During the time interval following the period studied in that publication, namely in 1980–1988, four earthquakes occurred in the region which had a magnitude ofM6.4 at least in one of the catalogs: Caltech or NOAA. Three earthquakes—Coalinga of May, 1983, Chalfant Valley of July, 1985 and Superstition Hills of November, 1987—were successfully predicted by the published algorithm.The missed event is a couple of two Mammoth Lake earthquakes of May, 1980 which we consider as one event due to their time-space closeness. This event occurred near the northern boundary of the region, and it also would have been predicted if we had moved the northern boundary from 38°N to the 39°N; the precision of the prediction in this case would be 30 km.The average area declared by the algorithm as the area of increased probability of strong earthquake, e.g., the area within 111-km distance of all long-range aftershocks currently present on the map of the region during 1980–1988 is equal to 47% of the total area of the region if the latter is measured in accordance with the density distribution of earthquakes in California, approximated by the catalog of earthquakes withM5. In geometrical terms it is approximately equal to 17% of the total area.Thus the result of the real time test shows a 1.6 times increase of the occurrence ofC-events in the alarmed area relative to the normal rate of seismicity. Due to the small size of the sample, it is of course, beyond the statistically significant value. We adjust the parameters of the algorithm in accordance with the new material and publish them here for further real-time testing.     

Structural geomorphology,active faulting and slope deformations in the epicentre area of the MW 7.0, 1857, Southern Italy earthquake

In tectonically active domains, fault propagation processes are revealed by landforms. A characteristic morphological feature of exposed active faults is the occurrence of triangular facets. Triangle-shaped landforms morphologically similar to fault-related triangular facets result from erosion of moderately-to-steeply dipping strata or layered successions along fold limbs and are known as flatirons. Triangular facets and flatirons may commonly coexist in mountain chains resulting from the superposition of recent extensional faulting on inherited fold-and-thrust architecture. In these settings analysis of flatirons and triangular facets is not trivial and may result in geomorphologic misinterpretations, hence undermine the interpretations of the geological structure and related deformation history. Here we show that active fault lineaments can be discriminate by inherited morpho-structure. We present the combined results of photo-geological and field survey carried out along well-exposed triangular shaped landforms located in the seismically active Upper Agri River Valley of the Southern Apennine. We found that triangular shaped landforms develop along a major fold back-limb, the Mt. Lama western slope, making it possible to unequivocally interpret these as flatirons. Downslope, Mt. Lama back limb is affected by a large deep-sited landslide whose scarp bound the flatirons and mimics a Holocene fault scarp. This inference appears significant, since the investigated landforms were interpreted by many authors as triangular facets related to an active normal fault, located at its foot, responsible for large historical earthquakes (i.e., the 1857 earthquake). We provide new criteria to discriminate morphologic convergence in tectonically active domains, with consequences for the regional geological interpretation, and for the assessment of geological hazards.     

Volcanological implications of crystal-chemical variations in clinopyroxenes from the Aeolian Arc, Southern Tyrrhenian Sea (Italy)

Crystal chemistry and structural data for clinopyroxene from the Aeolian islands (Southern Tyrrhenian Sea, Italy) were determined with the aim of obtaining geobarometric information and exploring implications for the structure of volcanic plumbing systems. Cell and M1 site volumes for clinopyroxenes, which are known to decrease with increasing pressure of crystallization, revealed variable values, both within some single islands and along the entire arc, indicating polybaric conditions of crystallization. The lowest cell and M1 volumes were found at Filicudi, plotting close to values of clinopyroxenes from high-pressure ultramafic xenoliths entrained in alkali basalts. Indications of high-pressure crystallization were also found at Salina and, to a lesser extent, at Alicudi, all situated in the western sector of the Aeolian Arc. The central and eastern islands of Lipari, Vulcano, Panarea and Stromboli generally show higher values of cell parameters, suggesting crystallization in shallow magma chambers. These islands are characterized by the occurrence of large calderas, which are apparently lacking at Salina and Filicudi. Time-related variations were observed for cell and M1 volumes of clinopyroxene for some islands. At Salina, the early-erupted products display low values of cell parameters with respect to later activity, thus indicating a decrease in crystallization pressure with time. A similar, although less striking, pattern is observed at Alicudi and Lipari. An overall increase in cell parameters with time was observed at the scale of the entire arc. The observed variations in clinopyroxene structural parameters highlight the significance of pyroxene crystal chemistry for petrogenetic and volcanological interpretation. Correlation with time and the structural characteristics of volcanoes suggest significant regional and temporal modifications in the plumbing systems of Aeolian volcanoes. Clinopyroxenes from Filicudi and the older Salina crystallized at high pressure in deep magma chambers, in the lower crust or at the mantle-crust boundary. The lower crystallization pressure in the younger Salina is interpreted as evidence of upward migration of magma chambers with time. Similar evolution can be envisaged for Alicudi. Instead, the entire evolutionary history of the central and eastern islands was dominated by low-pressure crystallization, with formation of calderas and generation of abundant acid products that are scarce or absent in the western islands. Evolution of the plumbing system of single volcanoes and of the Aeolian arc in general is probably related to modification of stress regimes and/or thinning of the arc basement, due to the effect of uprising mantle material above the Ionian subduction zone.     

Volcaniclastic debris-flow occurrences in the Campania region (Southern Italy) and their relation to Holocene–Late Pleistocene pyroclastic fall deposits: implications for large-scale hazard mapping

The Campania Region (southern Italy) is characterized by the frequent occurrence of volcaniclastic debris flows that damage property and loss of life (more than 170 deaths between 1996 and 1999). Historical investigation allowed the identification of more than 500 events during the last four centuries; in particular, more than half of these occurred in the last 100 years, causing hundreds of deaths. The aim of this paper is to quantify debris-flow hazard potential in the Campania Region. To this end, we compared several elements such as the thickness distribution of pyroclastic fall deposits from the last 18 ka of the Vesuvius and Phlegrean Fields volcanoes, the slopes of relieves, and the historical record of volcaniclastic debris flows from A.D. 1500 to the present. Results show that flow occurrence is not only a function of the cumulative thickness of past pyroclastic fall deposits but also depends on the age of emplacement. Deposits younger than 10 ka (Holocene eruptions) apparently increase the risk of debris flows, while those older than 10 ka (Late Pleistocene eruptions) seem to play a less prominent role, which is probably due to different climatic conditions, and therefore different rates of erosion of pyroclastic falls between the Holocene and the Late Pleistocene. Based on the above considerations, we compiled a large-scale debris-flow hazard map of the study area in which five main hazard zones are identified: very low, low, moderate, high, and very high.     

Quaternary faults and seismicity in the Umbro-Marchean Apennines (Central Italy): evidence from the 1997 Colfiorito earthquake

Analyses of structural and geomorphological data combined with remote sensing interpretation confirm previous knowledge on the existence of an extensional Quaternary tectonic regime in the Colfiorito area (Umbro-Marchean Central Apennines). This is characterized by a maximum principal axis of finite strain oriented approx. NE–SW, which is the result of a progressive deformation process due to pure and radial extension. Surface geological data, the crustal tectonic setting (reconstructed using a CROP 03 seismic reflection profile), and seismological data relative to the autumn 1997 Colfiorito earthquake sequence constrain the following seismotectonic model. We interpret the seismogenic SW-dipping low-angle normal fault pictured by seismic data as an inverted thrust ramp located in the basement at depth between 5 and 10 km. The surface projection of this seismogenic structure defines a crustal box within which high-angle normal faults are responsible for the deformation of the uppermost crust. The regional patterns of pre-existing basement thrusts therefore control the seismotectonic zoning of the area that cannot be directly related to the high-angle normal fault systems which cut through different crustal boxes; the latter system records, in fact, re-shear along pre-existing normal faults. Moreover, Quaternary slip-rates relative to high-angle normal faults in the Central Apennines are closely related to seismic hazard within each crustal box.     

Testing geomorphic signal of active normal faulting: The case of the Cittanova Fault (Calabria,southern Italy)

Extracting tectonic signals from the landscape is an important challenge for constraining the style and rate of deformation associated with active faults, especially where their displacement history cannot be independently determined. Based on previous paleoseismological data coupled with new geomorphological field work and ¹⁴C dating of geomorphic markers, we analysed the geomorphic signal of the along‐strike differential throw of the Cittanova Fault in southern Calabria (Italy), the recent activity of which is already well documented and constrained. Through DTM‐derived stream power law parameters (SL and χ), we provide evidence of drainage network disequilibrium and reorganization in response to fault growth and deformation style. Furthermore, a methodological test of the reliability of the χ metric as a proxy for the differential throw along the strike of active normal faults provided good preliminary results, consistent with a strong inverse linear correlation with fault throw. Copyright © 2018 John Wiley & Sons, Ltd.     

New constraints on the seismic history of the Castrovillari fault in the Pollino gap (Calabria, southern Italy)

The Pollino Range area represents the mostprominent gap in seismicity within thesouthern Apennines. Geomorphic andtrenching investigations along theCastrovillari fault indicate that thisnormal fault is a major seismogenic faultwithin the southern part of this gap. Atleast four surface-faulting earthquakeshave occurred on this fault since latePleistocene age. Radiocarbon dating coupledwith historical consideration set thetime of the most recent earthquake as mostlikely to be between 530 A.D. and 900 A.D.,with the possible widest interval of530–1100 A.D. No evidence for this eventhas been found in the historical records,although its age interval falls within thetime spanned by the seismic catalogues.Slip per event ranges between 0.5 and1.6 m, with a minimum rupture length of13 km. These values suggest a M 6.5–7.0 forthe paleoearthquakes. The minimum long-termvertical slip rate obtained from displacedgeomorphic features is of 0.2–0.5 mm/yr. Avertical slip-rate of about 1 mm/yr is alsoinferred from trenching data. Theinter-event interval obtained from trenchdata ranges between 940 and 7760 years(with the young part of the intervalpossibly more representative; roughly940–3000 years). The time elapsed since themost recent earthquake ranges between aminimum of 900–1100 and a maximum of 1470years. The seismic behavior of this faultappears to be consistent with that of othermajor seismogenic faults of thecentral-southern Apennines. The Pollinocase highlights the fact thatgeological investigations represent apotentially useful technique tocharacterize the seismic hazard of `silent' areas for which adequate historical andseismological data record are notavailable.     

Seismotectonics and seismic quietness of the Oranie region (Western Algeria): The Mascara earthquake of August 18th 1994, Mw = 5.7, Ms = 6.0

The plate dynamics in the central western Mediterranean region is characterised by a collision between the Eurasian and African plates. In response to this dynamics, many systems of faults and folds having a NE-SW and E-W trending have been generated along the Tellian Atlas of Algeria. The Oranie region (north western Algeria) has experienced some significant earthquakes in the last centuries, the most important one is that of Oran city on February 9^th 1790, I_o = XI which destroyed the town completely and caused the loss of many lives. Since 1790 no other event was so disastrous except that of August 18^th 1994, M_w = 5.7, which struck Mascara province (Algeria) at 01 h 13 mn GMT. Since the beginning of this century the region has been dominated by a seismic quietness. Thus, no event with magnitude larger than 5.5 have occurred in this area. In relation with this recent event, a seismotectonic framework summarising the tectonic, seismicity and focal solution results is presented. The Maximum Observed Intensities Map (MOI) made for Algeria (Bezzeghoud et al., 1996) is also used to show that the Mascara region is located in an VIII-X intensity zone, which explain partially the casualties caused by the 18/08/1994 (M_w = 5.7) earthquake. This earthquake is not anomalous compared to historical records but is unusual compared to recorded seismicity of this century. The seismotectonic map made in this study and also the review of the focal solutions given by the EMSC, Harvard, and other authors shows that our event is probably associated with a source belonging to a system of faults located in the vicinity of the village of Hacine where the maximum damage was observed.     

Raised Holocene paleo-shorelines along the Capo Vaticano coast (western Calabria,Italy): Evidence of co-seismic and steady-state deformation

Detailed mapping of geomorphological and biological sea-level markers around the Capo Vaticano promontory (western Calabria, Italy), has documented the occurrence of four Holocene paleo-shorelines raised at different altitudes. The uppermost shoreline (PS1) is represented by a deeply eroded fossiliferous beach deposit, reaching an elevation of ∼2.2 m above the present sea-level, and by a notch whose roof is at ∼2.3 m. The subjacent shoreline PS2 is found at an elevation of ∼1.8 m and is represented by a Dendropoma rim, a barnacle band and by a wave-cut platform. Shoreline PS3 includes remnants of vermetid concretions, a barnacle band, a notch and a marine deposit, and reaches an elevation of ∼1.4 m. The lowermost paleo-shoreline (PS4) includes a wave-cut platform and a notch and reaches an elevation of ∼0.8 m. Radiocarbon dating of material from individual paleo-shorelines points to an average uplift rate of 1.2–1.4 mm/yr in the last ∼6 ka at Capo Vaticano. Our data suggest that Holocene uplift was asymmetric, with a greater magnitude in the south-west sector of the promontory, in a manner similar to the long-term deformation attested by Pleistocene terraces. The larger uplift in the south-western sector is possibly related to the additional contribution, onto a large-wavelength regional signal, of co-seismic deformation events, which are not registered to the north-east. We have recognized four co-seismic uplift events at 5.7–5.4 ka, 3.9–3.5 ka, ∼1.9 ka and <1.8 ka ago, superposed on a regional uplift that in the area, is occurring at a rate of ∼1 mm/yr. Our findings places new constrains on the recent activity of border faults south of the peninsula and on the location of the seismogenic source the 1905 destructive earthquake.