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Palombo, Barbara
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Palombo, Barbara
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barbara.palombo@ingv.it
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- PublicationRestrictedStudy of site effects in the area of Nocera Umbra (central Italy) during the 1997 Umbria-Marche seismic sequence(2000)
; ; ; ; ; ; ; ; ;Caserta, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Bellucci, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Cultrera, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Donati, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Marra, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Mele, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Palombo, B.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Rovelli, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; ; ; ; ; ; 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.289 27 - PublicationOpen AccessBroad-band moment tensor inversion from single station, regional surface waves for the 1990, NW-Iran earthquake sequence(1994-12)
; ; ; ; ;Giardini, D.; Dipartimento di Scienze Geologiche, III Università di Roma, Italy ;Malagnini, L.; Istituto Nazionale di Geofisica, Roma, Italy ;Palombo, B.; Istituto Nazionale di Geofisica, Roma, Italy ;Boschi, E.; Istituto Nazionale di Geofisica, Roma, Italy; ; ; e present a method for the inversion of complete waveforms in the 5-30 mHz frequency band for moment tensor determination. The method is based on the calibration of phase and group velocity dispersion curves for Rayleigh and Love fundamental modes to account for heterogeneous lithospheric structure, and is applied to the analysis of single station records of the VSL MEDNET station for the 1990 NW Iran earthquake sequence (the events of June 20, 21 and 24). The revised seismic moment of the June 20, 1990 Iranian earthquake is Mo = 1.56 x 1027 dyne-cm, corresponding to Mw = 7.4. The method proves to be a very robust tool for the analysis of moderate and large earthquakes at regional distances, producing consistent moment tensor solutions trom single station inversions in narrow (2-4 mHz) and wide (up to 20 mHz) frequency bands across the whole band of interest.298 295 - PublicationOpen AccessInvestigation on static stress interaction among the 1930 Irpinia Earthquake and other large events in Southern Apennines (Italy)(2007-07)
; ; ; ; ;Perniola, B.; Istituto di Fisica, Università di Urbino, Urbino (PU), Italia ;Fracassi, U.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Palombo, B.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Pino, N. A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; ; ; 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.239 7650 - PublicationOpen AccessRU4.02TaskB: Source parameters of significant italian historical earthquakes within the SISMOS project framework(2009-10)
; ; ; ; ;Palombo B1., B.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Bernardi, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Ferrari, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Hunstad, I.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; ; ; We have analyzed 18 out of the selected 19 events of the Italian seismic history. We have paid particular attention to the Adriatic coast earthquakes, 1908 Calabro Messinese and the 1917 Sansepolcro earthquakes. The historical bulletins, the instrumental parameters and the paper seismograms for all the 13 events have been recovered. The relocation of the events for which we have the complete set of data (the P and S arrival times and the paper records to read the missing arrival times) was carried out. We have vectorialized seismograms for the recovered components of the following earthquakes: Calabria 1905, Calabro Messinese 1908, Monterchi-Citerna 1917, Senigallia 1930, Adriatic reagion1934,1938, 1962. For the earthquakes occurred during war periods, is very difficult to find the bulletins, the paper seismograms and the instrument parameters. However, for the 1916 Adriatic earthquake we have enough bulletins to estimate the instrumental location. The Sismos team has developed a new methodology to compute the moment tensor. This method has the advantage to be suitable for historical dataset, but require long time computation even using the new multi-dualcore computers. Using this technique we have calculated the moment tensor and magnitude for the 1917 San Sepolcro earthquake using amplitudes from digitized seismograms, while polarities come from both bulletins and seismograms reading.209 314 - PublicationRestrictedWaveform modeling of historical seismograms of the 1930 Irpinia earthquake provides insight on ‘‘blind’’ faulting in Southern Apennines (Italy)(2008)
; ; ; ; ; ;Pino, N. A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia ;Palombo, B.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Ventura, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Perniola, B.; universita' di urbino ;Ferrari, G.; SGA bologna; ; ; ; 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 setting261 27 - PublicationRestrictedLarge amplification of ground motion at rock sites within a fault zone in Nocera Umbra (central Italy)(2000)
; ; ; ; ; ; ; ; ; ;Marra, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Azzara, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Bellucci, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Caserta, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Cultrera, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Mele, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Palombo, B.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Rovelli, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Boschi, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione AC, Roma, Italia; ; ; ; ; ; ; ; 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.313 31 - PublicationOpen AccessOn the recovery and analysis of historical seismogramsThe analysis of historical seismograms has proven to be a fundamental tool to help with the definition of the seismic risk in specific regions. In- deed, modern quantitative reappraisal of relevant earthquakes that oc- curred before the 1960’s; i.e., prior to both the developments of modern recording instruments and the theoretical progress, has been essential for the assessment of the seismic potential of a source area. However, due to the characteristics (transducing and recording) of the old analog seismographs, the data available are affected by intrinsic uncertainties, and errors can be introduced during the processing of waveform digiti- zation. These drawbacks can seriously influence the quality and relia- bility of an investigation. In general, no standard technique can be applied when dealing with historical seismograms. Thus, specific tests and cross-checks have to be designed to estimate the limits of each spe- cific analysis. Here, we aim to provide an overview of the whole proce- dure while focusing on the most crucial steps, from the seismogram recovery to the application of modern techniques for the retrieval of the seismic source information. We also suggest possible checks for the ro- bustness of the data and for the available instrument characteristics, with a description of the effects of various uncertainties on the results that can be obtained. We thus provide useful indications for the analy- sis of historical seismograms, and also for the correct interpretation of the resulting characteristics of the seismic source.
73 29 - PublicationOpen AccessMoment tensor inversion of early instrumental data: application to the 1917 High Tiber Valley, Monterchi earthquake(2016)
; ; ; ; ; ; ; In this paper we present a new study on the High Tiber Valley earthquake occurred on April 26, 1917. Using the digitized data from mechanical seismograph records, we computed the source parameters like focal mech- anism and moment magnitude from moment tensor (MT). The study of historical earthquakes from an instrumental perspective is crucial because of the complexity of problems associated with the study of seismograms of moderate to large earthquakes occurred from the late 19th century until the early 1960s. Since historical earthquake records show significant un- certainties in phase arrival times and have been recorded by seismograph generally with short natural period, we developed a code to compute the MT based on a forward modeling technique, which uses the amplitude spectra of the full waveform length and the first P-arrival polarities to constrain the P- and T-axes. The best solution is determined by the best fit between the observed and synthetic amplitude spectra and from the co- herency between the observed and the theoretical first P-arrival polarities. The 1917 High Tiber Valley earthquake is one of the most important 20th century earthquake occurred in the Italian Peninsula for which the focal mechanism and moment magnitude from seismic records are not avail- able. Additionally, we apply a multidisciplinary approach to character- ize the source of this earthquake, combining instrumental, macroseismic, geological and tectonic data and investigations. The computed MT re- sults in a north-south normal fault mechanism (strike: 147°, dip: 29°, slip: −94°), which is consistent with the strike estimated from the macro- seismic data (157°). The moment magnitude calculated from the MT and that derived from the macroseismic data are Mw=5.5±0.2 and Mw=5.9±0.1, respectively.302 15 - PublicationOpen AccessLong-period modelling of MEDNET waveforms for the December 13, 1990 Eastern Sicily earthquake(1995-05)
; ; ; ;Giardini, D.; Dipartimento di Scienze Geologiche, III Università degli Studi, Roma ;Palombo, B.; Istituto Nazionale di Geofisica, Roma, Italy ;Pino, N. A.; Istituto Nazionale di Geofisica, Roma, Italy; ; The availability of broad-band digital data allow "the analysis" of the seismic signal in the low-noise frequency band for structural and seismic source studies, We model complete seismograms -surface and body waves - for the December 13, 1 990, Eastern Sicily earthquake, recorded at regional distances on the MEDNET stations AQU, BNI and KEG, The inversion for the moment tensor is carried out following two approaches: a) a model-independent stralegy to fit complete seismograms in the 100-130 s period range; b) the calibration of phase velocity curves along each path to fit surface waves in the 40-100 s range, Both methodologies yield stable and consistent results: the 1990 Eastern Sicily earthquake had a seismic moment of M/o = 37 x 1024 dyne.cm, corresponding lo magnitude values of mb = 5,5, Ms = 5,7, Mw = ML = 5.8. In a second stage, synthetic seismograms arc generated by full reflectivity in the 5-50 s period range, with a new code based on the "minors" integration. By modelling surface waves in the 30-50 s range and body waves to 5 s periods, we derive average velocity models for the Central and Eastern Mediterranean, and constrain the hypocenter of the 1990 Eastern Sicily earthquake to be in the 13-17 km depth range.327 189 - PublicationOpen AccessThe source of the 30 October 1930, Mw 5.8, Senigallia (central Italy) earthquake: a convergent solution from instrumental, macroseismic, and geological data(2015-05)
; ; ; ; ; ;Vannoli, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Vannucci, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Bernardi, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Palombo, B.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Ferrari, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia; ; ; ; 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.646 82