We present the results of seismological and geophysical investigations performed by the “
Istituto Nazionale di Geofisica e Vulcanologia
” team operating in Amatrice village (Central Italy), in the ...emergency phases following the Mw 6.0 event of August 24th 2016, that caused severe damage in downtown and surrounding areas. Data from seven seismic stations equipped with both weak and strong motion sensors are analyzed in terms of standard spectral ratio to empirically define amplification function using a bedrock reference site. Ambient vibration spectral ratios between horizontal and vertical component of motion are also evaluated in a large number of sites, spread out in the investigated area, to recover the resonance frequency of the soft soil outcropping layers and to generalize the results obtained by earthquake data. Ambient noise vibration are also used for applying a 2D array approach based on surface waves techniques in order to define the near-surface velocity model and to verify its lateral variation. The results allows to better understand the amplification factors in the investigated area, showing spatial variation of site effects despite of the homogeneous shallow geological condition indicated by the microzonation studies available at moment of the described field campaign. The analysis reveals a diffuse amplification effect which reaches its maximum values in downtown area with a resonant frequency of about 2 Hz. The obtained results were used to integrate the microzonation studies and they can be used for urban planning and reconstruction activities.
In this paper we describe the macroseismic effects produced by the long and destructive seismic sequence that hit Central Italy from 24 August 2016 to January 2017. Starting from the procedure ...adopted in the complex field survey, we discuss the characteristics of the building stock and its classification in terms of EMS-98 as well as the issues associated with the intensity assessment due to the evolution of damage caused by multiple shocks. As a result, macroseismic intensity for about 300 localities has been determined; however, most of the intensities assessed for the earthquakes following the first strong shock on 24 August 2016, represent the cumulative effect of damage during the sequence. The earthquake parameters computed from the macroseismic datasets are compared with the instrumental determinations in order to highlight critical issues related to the assessment of macroseismic parameters of strong earthquakes during a seismic sequence. The results also provide indications on how location and magnitude computation can be strongly biased when dealing with historical seismic sequences.
In this paper we describe an advanced database for the site characterization of seismic stations, named “CRISP—Caratterizzazione della RIsposta sismica dei Siti Permanenti della rete sismica” (
...http://crisp.ingv.it
, quoted with
https://doi.org/10.13127/crisp
), designed for the Italian National Seismic Network (Rete Sismica Nazionale, RSN, operated by Istituto Nazionale di Geofisica e Vulcanologia). For each site, CRISP collects easily accessible station information, such as position, type(s) of instrumentation, instrument housing, thematic map(s) and descriptive attributes (e.g., geological characteristics, etc.), seismic analysis of recordings, and available geophysical investigations (shear-wave velocity
V
S
profile, non-linear decay curve). The archive also provides key proxy indicators derived from the available data, such as the time-averaged shear-wave velocity of the upper 30 m from the surface (V
S30
) and site and topographic classes according to the different seismic codes. Standardized procedures have been applied as motivated by the need for a homogenous set of information for all the stations. According to European Plate Observing System infrastructural objectives for the standardization of seismological data, CRISP is integrated into pre-existing INGV instrument infrastructures, shares content with the Italian Accelerometric Archive, and complies map information about the stations, as well as local geology, through web services managed by Istituto Superiore per la Protezione e la Ricerca Ambientale. The design of the CRISP archive allows the database to be continually updated and expanded whenever new data are available from the scientific community, such as the ones related to new seismic stations, map information, geophysical surveys, and seismological analyses.
In this study data and results of a high-resolution experiment in Cephalonia (Greece) regarding empirical basin effects are presented. A total of 59 velocimeters and 17 accelerometers were deployed ...in the basin of Argostoli Cephalonia (Greece), for a period of 7 months (September 2011–April 2012). Due to high seismicity of the western Greece and surrounding area this array recorded thousands of local, regional and global events. Data used in this work come from a selection of 162 regional and local earthquakes, 3 km ≤ R ≤ 600 km, with magnitude range, 1.0 ≤ M ≤ 5.2. Based on high signal-to-noise ratio recordings and two selected reference stations, variation of several intensity measures (PGA, PGV, Arias Intensity, Cumulative Absolute Velocity), significant duration, HVSR and SSR of ground motion recordings on soil sites within the basin is carefully examined for a range of frequencies of engineering interest. Comparison of results with a detailed 2D geologic model shows a good consistency both in amplification and frequency domain. Influence of “reference” site on ground motion variation of soil sites is also discussed in light of our results. Finally, it is suggested that 2D or/and 3D theoretical modeling should be performed given the availability of geological and geophysical parameters to define a realistic model of the basin. Results of this study can undoubtedly serve in model validation and improvement of ground motion simulation tools.
After the 2009 April 6th Mw 6.3 L’Aquila earthquake (Central Italy) the Italian Civil Defense Department promoted the microzoning study in the ten zones in the epicentral area that suffered major ...damage. In this paper we present the activities and the results concerning a temporary seismic network installed in the historical L’Aquila city center indicated as “macroarea 1” in the microzoning project. Seismic data were collected to investigate the amplification effects in the city and to support the microzoning activities in verifying both geological profiles and 1D numerical modeling of the seismic response of the city. The conventional spectral approaches using both microtremor and earthquake data allowed to determine the fundamental resonance frequencies and the amplification factors within the city respectively. The spatial variability of these quantities can be related to the geological and geomorphologic characteristics of the investigated area. A comparison between the network data and the data recorded by the two strong motion instruments installed in the city was also made. This allows verifying the relative response of the accelerometric stations that recorded in the city the major events of the sequence.
A temporary network of 33 seismic stations was deployed in the area struck by the 6th April 2009, Mw 6.1 (Scognamiglio et al. in Seism Res Lett 6/81,
2010
), L’Aquila earthquake (central Italy), with ...the aim to investigate the site amplification within the Aterno river Valley. The seismograms of 18 earthquakes recorded by 14 of the 33 stations were used to evaluate the average horizontal to vertical spectral ratio (HVSR) for each site and the standard horizontal spectral ratio (SSR) between a site and a reference station. The obtained results have been compared to the geological and geophysical information in order to explain the resonance frequencies and the amplification levels with respect to surface geology of the valley. The results indicate that there is no uniform pattern of amplification, because of the complex geologic setting, as the thickness and degree of cementation of the deposits is highly variable.
Numerous studies demonstrate that memory recall is improved by reflecting upon, or revisiting, the environment in which information to-be-recalled was encoded. The current thesis sought to apply ...these ‘context reinstatement’ (CR) techniques in an attempt to improve the effectiveness of facial composites—likenesses of perpetrators constructed by witnesses and victims of crime. Participant-constructors were shown an unfamiliar target face in an unfamiliar environment (e.g., an unknown café). The following day, participants either revisited the environment (physical context reinstatement) or recalled the environmental context in detail along with their psychological state at the time (mental context reinstatement, Detailed CR); they then freely recalled the face and constructed a facial composite using a holistic (EvoFIT) or a feature system (PRO-fit). Over the course of five experiments and meta-analyses, Detailed CR of the environmental context was effective at increasing correct naming and likeness ratings of ensuing composites. The size of the advantage for Detailed CR was dependent on the extent to which the environment had been encoded: the advantage was (i) variable for incidental encoding (Experiments 1-3) with an overall small effect size (ES) (assessed by meta-analysis), (ii) best (very large ES) under intentional encoding (Experiment 3) and (iii) intermediate (large ES) for incidental encoding when participants were encouraged to engage naturally with the environment (Experiment 4). Detailed CR was also found to be effective when combined with a specific interviewing technique (Holistic-Cognitive Interview) where constructors focused on the target’s character; it was no more effective when constructors were prompted to recall the environment in greater detail. Further analyses (Meta-analyses) and additional data (Experiment 5) indicate that the advantage of Detailed CR was mediated by an increase in constructor’s total face recall. Results are interpreted in terms of the encoding specificity principle and can be applied by forensic practitioners who use feature and recognition systems. This thesis is the first to reveal that context cues can be implemented effectively during forensic face construction using modern composite systems.
The 24 August 2016 earthquake very heavily struck the central sector of the Apennines among the Lazio,Umbria, Marche and Abruzzi regions, devastating the town of Amatrice, the nearby villages and ...other localities along the Tronto valley. In this paper we present the results of the macroseismic field survey carried out using the European Macroseismic Scale (EMS) to take the heterogeneity of the building stock into account. We focused on the epicentral area, where geological conditions may also have contributed to the severity of damage. On the whole, we investigated 143 localities; the maximum intensity 10 EMS has been estimated for Amatrice, Pescara del Tronto and some villages in between. The severely damaged area (8-9 EMS) covers a strip trending broadly N-S and extending 15 km in length and 5 km in width; minor damage occurred over an area up to 35 km northward from the epicenter.
SUMMARY
In the last decade the use of passive methods has become appealing in reconstructing the properties of the propagation medium by seismic ambient noise data, without the use of localized ...natural or artificial sources. A temporary seismic network was installed in the urban area of Benevento (southern Italy) in order to characterize the shallow structure of the city using stable methods for the analysis of the seismic noise continuously acquired by stations. The city of Benevento is one of the italian areas with highest seismic hazard, and at present the region is affected by low energy swarms and sparse events (Ml ≤ 4.1). It has been struck by several destructive historical earthquakes, the strongest of which occurred in 1456, 1688, 1805 with associated MCS intensity up to X–XI. We used the sixteen seismic stations installed in Benevento to record ambient noise for about 1 month. The stations were equipped with different seismic instruments: (i) digitizers Quanterra Q330 connected to Le3d-5 s short-period sensors; (ii) Nanometrics Centaur digitizers coupled with Trillium Compact 120s broad-band velocimeters; (iii) one station with Episensor force balance accelerometer connected to a D6BB-DIN Staneo digitizer. Interstations Green's functions were reconstructed by the cross-correlation of continuous ambient noise data, and surface waves signals were extracted from Green's Functions (GFs) for investigating the elastic properties of the subsurface structure. In this regard, we performed the beamforming analysis to test the hypothesis of isotropy distribution of noise sources on which the cross-correlation method is based, and the particle motion analysis to confirm the presence of surface Rayleigh waves in the GFs. We analysed the temporal stability of the cross-correlated signals and the results show that 2 weeks of continuous measurements are sufficient to stabilize the surface waves signal extracted from the GFs. The phase velocity dispersion curves are computed for 115 station pairs through the use of a far-field representation of the surface-wave GFs and an image transformation technique. Our strategy based on cross-correlation analysis provides robust phase-velocity dispersion curves that vary approximately from 1.4 km s–1 at 0.7 Hz to 0.6 km s–1 at 5 Hz. Different pairs were selected for the inversion of phase-velocity dispersion curves aimed to derive 1-D shear-wave velocity (Vs) profiles (up to a maximum depth of about 500 m) representative of some areas of the city characterized by different soil deposits.
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