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  • 1
    ISSN: 1573-157X
    Keywords: Nocera Umbra ; site effects ; weak motions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract During the ML = 5.6 and 5.8 earthquakes occurredin central Italy on 26 September 1997 the historiccentre of Nocera Umbra, lying on top of a 120 m highhill, was diffusely damaged (VII-VIII degrees of MCSintensity). Some recently built houses in the modernpart of the town suffered an even higher level ofdamage. A temporary seismic array was deployed toinvestigate a possible correlation between localamplifications of ground motion in this area and theobserved pattern of damage. After a geologic andmacroseismic survey, eight sites were selected asrepresentative of different local conditions, such astopographic irregularities, sharp hard-to-softlithology transitions, alluvium-filled valleys, andboth undisturbed and deformed rocks.Horizontal-to-vertical spectral ratios for bothmicrotremor and earthquake recordings, as well asspectral ratios referred to undisturbed rock sites,were used to quantify local variations of groundmotion. In spite of the diffuse damage in the historiccentre of Nocera Umbra, a small amplification isobserved at the stations on the hill's top. Thissuggests that the higher vulnerability of the ancientbuildings mainly accounts for the diffuse damage inthat part of the town. In the frequency band ofengineering interest (1 to 10 Hz) the largestamplifications of ground motion are found at softsites: in the Topino river valley, where many episodesof severe structural damage occurred, spectralamplification is significant over a broad frequencyband ranging from 2 Hz to more than 20 Hz. Inparticular, in the central part of the valley highamplification (〉 4) is found from 3 to 10 Hz,reaching a maximum of 20 around 4 Hz. At the edge ofthe valley, close to the soil-to-rock transition,amplification is as large as 10 in a frequency bandranging from 4 to more than 20 Hz. A significantamplification (by a factor of 10 around 10 Hz) isobserved also at one of the rock sites, possibly dueto the presence of a cataclastic zone related to theactivity of a regional fault that altered themechanical properties of the rock.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-157X
    Keywords: fault zone ; ground motion ; Nocera Umbra ; site effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract During the two mainshocks of September 26, 1997 inthe Umbria-Marche border a strong-motion accelerographrecorded peak ground accelerations as large as 0.6 g,approximately, in the town of Nocera Umbra, atdistances of 10 to 15 km from the epicentres. Thisvalue is significantly larger than expected on thebasis of the usual regressions with magnitude anddistance. A broad-band amplification up to a factor of10 was consistently estimated in previous papers,using both weak and strong motion data recorded at theaccelerograph site during local moderate earthquakes.To study the cause of this amplification we deployedsix seismologic stations across the tectonic contactbetween the Ceno-Mesozoic limestone and the Mesozoicmarly sandstone where the accelerograph is installed.Seismograms of 21 shallow aftershocks in the magnituderange from 2.2 to 4.0 and a subcrustal Mw = 5.3event are analysed. Regardless of epicentre location,waveforms show a large complexity in an approximately200 m wide band adjacent to the tectonic contact. Thisis interpreted as the effect of trapped waves in thehighly fractured, lower velocity materials within thefault zone.
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2015-06-09
    Description: On 30 October 1930, an M w  5.8 earthquake hit the northern Marche coastal area (central Italy), causing significant damage ( I 0 VIII–IX degree Mercalli–Cancani–Sieberg) along a 40 km stretch of the Adriatic coast between Pesaro and Ancona, centered on the town of Senigallia. This area is characterized by relatively infrequent and moderate-sized earthquakes and by elusive active faults. In spite of the presence of well-known northwest–southeast-trending, northeast-verging fault-propagation folds forming the outer thrusts of the Apennines, the current level of activity, and the kinematics of these coastal structures are still controversial. We present a multidisciplinary analysis of the source of the 30 October 1930 Senigallia earthquake, combining instrumental and macroseismic data and elaborations with available evidence from geological and tectonic investigations. We determine the main seismic parameters of the source, including the earthquake location, its magnitude, and, for the first time, its focal mechanism, providing the first instrumental evidence for thrust faulting along the northern Marche coastal belt. Our findings provide conclusive evidence for the current activity of the northern Marche coastal thrusts. As such they have significant implications for the seismic hazard of the area, a densely populated region that hosts historical heritage, tourism facilities, industrial districts, and key transportation infrastructures. Online Material: Description of method used for moment tensor computation, tables of focal mechanisms and recording stations, and figures of seismic flux and uncertainty maps for macroseismic epicenters.
    Print ISSN: 0037-1106
    Electronic ISSN: 1943-3573
    Topics: Geosciences , Physics
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  • 4
    Publication Date: 2021-03-02
    Description: On 30 October 1930, an Mw 5.8 earthquake hit the northern Marche coastal area (central Italy), causing significant damage (I0 VIII–IX degree Mercalli–Cancani– Sieberg) along a 40 km stretch of the Adriatic coast between Pesaro and Ancona, centered on the town of Senigallia. This area is characterized by relatively infrequent and moderate-sized earthquakes and by elusive active faults. In spite of the presence of wellknown northwest–southeast-trending, northeast-verging fault-propagation folds forming the outer thrusts of the Apennines, the current level of activity, and the kinematics of these coastal structures are still controversial. We present a multidisciplinary analysis of the source of the 30 October 1930 Senigallia earthquake, combining instrumental and macroseismic data and elaborations with available evidence from geological and tectonic investigations.We determine the main seismic parameters of the source, including the earthquake location, its magnitude, and, for the first time, its focal mechanism, providing the first instrumental evidence for thrust faulting along the northern Marche coastal belt. Our findings provide conclusive evidence for the current activity of the northern Marche coastal thrusts. As such they have significant implications for the seismic hazard of the area, a densely populated region that hosts historical heritage, tourism facilities, industrial districts, and key transportation infrastructures.
    Description: Published
    Description: 1548-1561
    Description: 2T. Tettonica attiva
    Description: JCR Journal
    Description: reserved
    Keywords: 1930 Senigallia earthquake ; seismogenic source ; Northern Marche ; Thrust fault ; Focal mechanism ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
    Publication Date: 2021-03-31
    Description: On 21 August 1962 an earthquake sequence set off near the city of Benevento, in Italy's southern Apennines. Three earthquakes, the largest having Mw 6.1, struck virtually the same area in less than 40 min (at 18:09, 18:19 and 18:44 UTC, respectively). Several historical earthquakes hit this region, and its seismic hazard is accordingly among the highest countrywide. Although poorly understood in the past, the seismotectonics of this region can be revealed by the 1962 sequence, being the only significant earthquake in the area forwhichmodern seismograms are available. We determine location, magnitude, and nodal planes of the first event (18:09 UTC) of the sequence. The focal mechanismexhibits dominant strike-slip rupture along a north-dipping, E-W striking plane or along a west-dipping, N-S striking plane. Either of these solutions is significantly different fromthe kinematics of the typical large earthquakes occurring along the crest of the Southern Apennines, such as the 23 November 1980 Irpinia earthquake (Mw 6.9), caused by predominant normal faulting along NW-SE-striking planes. The epicentre of the 21 August 1962, 18:09 event is located immediately east of the chain axis, near one of the three north-dipping, E-W striking oblique-slip sources thought to have caused one of the three main events of the December1456 sequence (Io XIMCS), the most destructive events in the southern Apennines known to date. Wemaintain that the 21August 1962, 18:09 earthquake occurred along the E-Wstriking fault systemresponsible for the southernmost event of the 1456 sequence and for two smaller but instrumentally documented events that occurred on 6May 1971 (Mw 5.0) and 27 September 2012(Mw 4.6), further suggesting that normal faulting is not the dominant tectonic style in this portion of the Italian peninsula.
    Description: Published
    Description: 375-384
    Description: 2T. Tettonica attiva
    Description: JCR Journal
    Description: open
    Keywords: 1962 Irpinia earthquake ; Multiple earthquake ; Focal mechanism ; Strike-slip faulting ; Active tectonics ; Seismic hazard ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
    Publication Date: 2017-04-04
    Description: During the two mainshocks of September 26, 1997 in the Umbria-Marche border a strong-motion accelerograph recorded peak ground accelerations as large as 0.6 g, approximately, in the town of Nocera Umbra, at distances of 10 to 15 km from the epicentres. This value is significantly larger than expected on the basis of the usual regressions with magnitude and distance. A broad-band amplification up to a factor of 10 was consistently estimated in previous papers, using both weak and strong motion data recorded at the accelerograph site during local moderate earthquakes. To study the cause of this amplification we deployed six seismologic stations across the tectonic contact between the Ceno-Mesozoic limestone and the Mesozoic marly sandstone where the accelerograph is installed. Seismograms of 21 shallow aftershocks in the magnitude range from 2.2 to 4.0 and a subcrustal Mw = 5.3 event are analysed. Regardless of epicentre location, waveforms show a large complexity in an approximately 200 m wide band adjacent to the tectonic contact. This is interpreted as the effect of trapped waves in the highly fractured, lower velocity materials within the fault zone.
    Description: Published
    Description: 543-554
    Description: JCR Journal
    Description: reserved
    Keywords: site effects ; central Italy ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
    Publication Date: 2012-02-03
    Description: The 1908 earthquake is one of the most catastrofic event in the italian history, recorded by most of the historical seismic stations existing at that time. Some of the seismograms recorded by these stations have already been used by many authors for the purpose of studying source characteristics, although only copies of the original recordings were available. Thanks to the Euroseismos project (2002-2007) and to the Seismos project, most of the original data (seismogram recordings and instrument parameter calibrations)for these events are now available in digital formats. The Sismos database has recently acquired many original seismograms and related instrumental parameters for the 1908 Messina earthquake, recorded by 14 stations distributed worldwide and never used before in previous works. We have estimated the main event parameters (i.e. location, Mw and focal mechanism) with the new dataset. The aim of our work is to provide the scientific community with a reliable size and source estimation for accurate and consistent seismic hazard evaluation in Sicily, a region characterized by long term high seismicity.
    Description: Unpublished
    Description: San Francisco
    Description: 3.1. Fisica dei terremoti
    Description: open
    Keywords: 1908 Messina earthquake ; seismological parameters ; 04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
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  • 8
    Publication Date: 2017-04-04
    Description: On July 23rd 1930, a strong earthquake (Ms=6.6) occurred in the Irpinia region, the most seismically active area of the Southern Apennines (Italy). Destructive effects were reported in a wide area of about 6300 km2, causing more than 1400 victims. The same region had already been struck by several large earthquakes in 1456 (Me=6.9), 1694 (Me=6.0), 1702 (Me=6.0), 1732 (Me=6.6), and 1910 (Me=5.9). Other major events have hit Irpinia since the 1930 earthquake, including that of 1962 (Mw = 6.2) and the catastrophic one of 23 Nov 1980 (Mw = 6.9). Formerly published studies concerning the 1930 Irpinia event include analysis of macroseismic data, first motion polarities and a single station waveforms. By using the available bulletins and the historical seismograms, in our previous study we estimated the source parameters in terms of focal mechanism, magnitude, hypocentral location and seismic moment. Fault length, rupture velocity and other characteristics are also obtained by performing body waveform inversion for moment rate retrieval. These results are here used to study the static stress transfer between the 1930 Irpinia earthquake and subsequent large events like the 1962, and 1980 ones in order to investigate the possible fault interaction and earthquake triggering. To improve our knowledge on the region of the1930 event, we also study the Coulomb stress field related to E-W trending seismogenic sources, responsible for the main sub-events of the multiple 1456 historical earthquake. Modelling of such effects is useful both to obtain more information on seismogenic sources and to gain an improved evaluation of seismic hazard in this region.
    Description: Submitted
    Description: Università di Perugia, Perugia, Italy
    Description: 3.2. Tettonica attiva
    Description: open
    Keywords: CFF ; 1930 Irpinia earthquake ; southern Apennines ; southern Italy ; 04. Solid Earth::04.06. Seismology::04.06.02. Earthquake interactions and probability ; 04. Solid Earth::04.06. Seismology::04.06.05. Historical seismology ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: Poster session
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  • 9
    Publication Date: 2017-04-03
    Description: The Southern Apennines chain is related to the west-dipping subduction of the Apulian lithosphere. The strongest seismic events mostly occurred in correspondence of the chain axis along normal NW–SE striking faults parallel to the chain axis. These structures are related to mantle wedge upwelling beneath the chain. In the foreland, faulting develops along E–W strike-slip to oblique-slip faults related to the roll-back of the foreland. Similarly to other historical events in Southern Apennines, the I0 = XI (MCS intensity scale) 23 July 1930 earthquake occurred between the chain axis and the thrust front without surface faulting. This event produced more than 1400 casualties and extensive damage elongated approximately E-W. The analysis of the historical waveforms provides the chance to study the fault geometry of this ‘‘anomalous’’ event and allow us to clarify its geodynamic significance. Our results indicate that the MS = 6.6 1930 event nucleated at 14.6 ± 3.06 km depth and ruptured a north dipping, N100 E striking plane with an oblique motion. The fault propagated along the fault strike 32 km to the east at about 2 km/s. The eastern fault tip is located in proximity of the Vulture volcano. The 1930 hypocenter, similarly to the 1990 (MW = 5.8) Southern Apennines event, is within the Mesozoic carbonates of the Apulian foredeep and the rupture developed along a ‘‘blind’’ fault. The 1930 fault kinematics significantly differs from that typical of large Southern Apennines earthquakes, which occur in a distinct seismotectonic domain on late Pleistocene to Holocene outcropping faults. These results stress the role played by pre-existing, ‘‘blind’’ faults in the Apennines subduction setting
    Description: Published
    Description: B05303
    Description: 3.2. Tettonica attiva
    Description: 3.10. Sismologia storica e archeosismologia
    Description: 5.2. TTC - Banche dati di sismologia strumentale
    Description: JCR Journal
    Description: reserved
    Keywords: southern apennines ; historical earthquakes ; 04. Solid Earth::04.06. Seismology::04.06.03. Earthquake source and dynamics
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 10
    Publication Date: 2017-04-04
    Description: During the ML = 5.6 and 5.8 earthquakes occurred in central Italy on 26 September 1997 the historic centre of Nocera Umbra, lying on top of a 120 m high hill, was diffusely damaged (VII-VIII degrees of MCS intensity). Some recently built houses in the modern part of the town suffered an even higher level of damage. A temporary seismic array was deployed to investigate a possible correlation between local amplifications of ground motion in this area and the observed pattern of damage. After a geologic and macroseismic survey, eight sites were selected as representative of different local conditions, such as topographic irregularities, sharp hard-to-soft lithology transitions, alluvium-filled valleys, and both undisturbed and deformed rocks. Horizontal-to-vertical spectral ratios for both microtremor and earthquake recordings, as well as spectral ratios referred to undisturbed rock sites, were used to quantify local variations of ground motion. In spite of the diffuse damage in the historic centre of Nocera Umbra, a small amplification is observed at the stations on the hill’s top. This suggests that the higher vulnerability of the ancient buildings mainly accounts for the diffuse damage in that part of the town. In the frequency band of engineering interest (1 to 10 Hz) the largest amplifications of ground motion are found at soft sites: in the Topino river valley, where many episodes of severe structural damage occurred, spectral amplification is significant over a broad frequency band ranging from 2 Hz to more than 20 Hz. In particular, in the central part of the valley high amplification (〉 4) is found from 3 to 10 Hz, reaching a maximum of 20 around 4 Hz. At the edge of the valley, close to the soil-to-rock transition, amplification is as large as 10 in a frequency band ranging from 4 to more than 20 Hz. A significant amplification (by a factor of 10 around 10 Hz) is observed also at one of the rock sites, possibly due to the presence of a cataclastic zone related to the activity of a regional fault that altered the mechanical properties of the rock.
    Description: Published
    Description: 555-565
    Description: JCR Journal
    Description: reserved
    Keywords: site effects ; Nocera Umbra ; 04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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