Papers by Dario Albarello
Geophysical Journal International, Feb 3, 2016
Synthetic dispersion curves are here computed in the frame of an ambient-vibration fullwavefield ... more Synthetic dispersion curves are here computed in the frame of an ambient-vibration fullwavefield model, which relies on the description of both ambient-vibration ground displacement and its sources as stochastic fields defined on the Earth's surface, stationary in time and homogeneous in space. In this model, previously developed for computing synthetic Horizontal-to-Vertical Spectral Ratio curves, the power spectral density function and the spatial autocorrelation of the displacement are naturally described as functions of the power spectral density function of the generating forces and of the subsoil properties (via the relevant Green's function), by also accounting for spatial correlation of these forces. Dispersion curves are computed from the displacement power spectral density function and from the spatial autocorrelation according with the well-known f-k and SPAC techniques, respectively. Two examples illustrate the way this new ambient-vibration model works, showing its possible use in better understanding the role of the surface waves in forming the dispersion curves, as well as its capability to capture some remarkable experimental findings.
Knowledge of the shear-wave velocity profile at strongmotion station sites is important for calib... more Knowledge of the shear-wave velocity profile at strongmotion station sites is important for calibrating accelerograms in terms of local site effects. Surface-wave seismic prospecting methods (both in active and passive configurations) provide an effective tool for an inexpensive and deep penetrating seismic characterization of subsoil. We used a combination of active (Multi-channel Analysis of Surface Waves, MASW) and passive (Extended Spectral AutoCorrelation, ESAC) array techniques along with the single-station ambient vibration measurements (Horizontal-to-Vertical Spectral Ratios - HVSR) to characterize strong-motion sites in Washington and Oregon. The MASW analysis was used to better constrain the shallowest part of the Vs profile, while effective dispersion curve provided by ESAC and HVSR data allow us to extend the survey downwards (up to hundred meters of depth). The combined use of these data in the frame of global-search inversion algorithms (Genetic Algorithms) allows us t...
Natural Hazards and Earth System Sciences, May 15, 2023
A methodology to detect local incompleteness of macroseismic intensity data at the local scale is... more A methodology to detect local incompleteness of macroseismic intensity data at the local scale is presented. In particular, the probability that undocumented effects actually occurred at a site is determined by considering intensity prediction equations (in their probabilistic form) integrated by observations relative to known events documented at surrounding sites. The outcomes of this analysis can be used to investigate how representative and known the seismic histories of localities are (i.e., the list of documented effects through time). The proposed approach is applied to the Italian area. The analysis shows that, at most of the considered sites, the effects of intensity ≥ 6 should most probably have occurred at least once, but they are not contained in the current version of the Italian macroseismic databases. In a few cases, instead, the lack of data may concern higher intensity levels (i.e., ≥ 8). The geographical distribution of potentially lost information reflects the heterogeneity of the seismic activity over the Italian territory.
EARTHQUAKE TRIGGERING IN THE PERI-ADRIATIC REGIONS INDUCED BY STRESS DIFFUSION: INSIGHTS FROM NUM... more EARTHQUAKE TRIGGERING IN THE PERI-ADRIATIC REGIONS INDUCED BY STRESS DIFFUSION: INSIGHTS FROM NUMERICAL MODELLING F. D’Onza (1), M. Viti (1), E. Mantovani (1) and D. Albarello (1) (1) Dept. of Earth Sciences, University of Siena - Italy ([email protected]/Fax:+39-0577-233820) Significant evidence suggests that major earthquakes in the peri-Adriatic Balkan zones may influence the seismicity pattern in the Italian area. In particular, a seismic correlation has been recognized between major earthquakes in the southern Dinaric belt and those in southern Italy. It is widely recognized that such kind of regularities may be an effect of postseismic relaxation triggered by strong earthquakes. In this note, we describe an attempt to quantitatively investigate, by numerical modelling, the reliability of the above interpretation. In particular, we have explored the possibility to explain the last example of the presumed correlation (triggering event: April, 1979 Montenegro earthquake, MS=6.7; ind...
ABSTRACT Results of probabilistic seismic hazard assessment (PSHA), in terms of macroseismic inte... more ABSTRACT Results of probabilistic seismic hazard assessment (PSHA), in terms of macroseismic intensity applied to the Mt. Etna region, are presented. PSHA has been performed using a numerical procedure based on the extensive use of local macroseismic information, as an alternative to the usual Cornell-McGuire methods. The large amount of intensity data available for this area - coming from the Italian intensity database DBMI04 for the regional earthquakes, and from the Etna catalogue for the ‘local’ events - has provided fairly exhaustive seismic site histories (i.e. the data set of macroseismic observations available for a given locality) to estimate the seismic hazard for 402 localities on the volcano. In order to improve the completeness of the site catalogue when historical information is missing, observed intensity data have been integrated with values calculated from epicentral information obtained by using an attenuation law specific for the Etna region. Using a probability distribution considering the completeness of the input database and the uncertainty of intensity data, the hazard in terms of maximum intensity (Iexp) characterised by a 10% probability of exceedance in an exposure time of 50 years, has been computed. The highest values ( Iexp = IX or X) are found in the south-eastern flank of Mt. Etna while the rest of the volcano is exposed to a lower hazard (Iexp = VIII). Despite the low energy (M≤4.8) compared with that of the large regional earthquakes affecting the area (6.6≤M≤7.4), the local events strongly influence the pattern of the hazard in the eastern sector of Mt. Etna, representing a significant, and sole, source of hazard when a shorter exposure time (e.g. 30 years) is considered. Published 77-91 4.2. TTC - Scenari e mappe di pericolosità sismica N/A or not JCR
Proseguimento della assistenza al DPC per il completamento e la gestione della appa di pericolosi... more Proseguimento della assistenza al DPC per il completamento e la gestione della appa di pericolosità sismica prevista dall'Ordinanza PCM 3274 e progettazione di ulteriori sviluppi Task 2-Realizzazione di valutazioni di pericolosità sismica in termini di intensità macrosismica ed effettuazione di confronti fra MPS04 e tali valutazioni Deliverable D9 Valutazioni di pericolosità sismica in termini di intensità macrosismica utilizzando metodi di sito D. Albarello (1) , R. Azzaro (2) , M.S. Barbano (3) , S. D'Amico (2) , V. D'Amico (1*) , R. Rotondi (4) , T. Tuvè (2) , G. Zonno (5)
ABSTRACT Seismic intensity is, by definition, an index for the classification of the severity of ... more ABSTRACT Seismic intensity is, by definition, an index for the classification of the severity of earthquake effects observed in a settlement. However the experience of many decades of its use within functional relations with other parametric quantities have shown that it represents a quite reliable estimator of ground motion amplitude and that it can be confidently related to instrumentally measured quantities by a logarithmic relation. Most intensity attenuation relations from the literature model empirically the difference between epicentral intensity I_0 (defined as the maximum observed intensity or something less that that) and the intensity at the site. This means assuming that I_0 is actually the average intensity observed at the epicenter and that it scales with site intensity with coefficient equal to 1. We analyzed the Italian macroseismic dataset that can be obtained by combining the two major Italian macroseismic databases following the choices made by the compilers of the parametric catalog of Italian earthquakes. It contains about 50,000 observations from ancient times to 1992. We considered an attenuation equation with log-linear dependence with hypocentral distance (depth fixed to 10 km) and an additional empirical term proportional to I_0 I_s=a + b D + c log{D} + d I_0 We found that: i) the intensity data observed at sites located at distance larger than the one at which the expected average intensity is below the limit of diffuse perceptibility (degree IV) are clearly incomplete and might bias the resulting attenuation relation, ii) intensity data with uncertain estimates (i.e. VI-VII) have frequencies lower of about 30-50% than regular ones and thus must be modeled separately, iii) the average intensity at the epicenter is on average from one to two degrees lower than I_0, iv) epicentral intensity contributes to the attenuation relation with a coefficient significantly different from 1.0 (about 0.7-08) thus indicating the it cannot be considered a reference ground-motion level but rather an estimator of the energy of the earthquake, v) the statistical distribution of intensity residuals closely resembles a normal one but with a significant skewness that can be appropriately modeled by a modified Azzalini distribution.
Proseguimento della assistenza al DPC per il completamento e la gestione della mappa di pericolos... more Proseguimento della assistenza al DPC per il completamento e la gestione della mappa di pericolosità sismica prevista dall'Ordinanza PCM 3274 e progettazione di ulteriori sviluppi Task 2-Realizzazione di valutazioni di pericolosità sismica in termini di intensità macrosismica ed effettuazione di confronti fra MPS04 e tali valutazioni Deliverable D11 Aggiornamento relazioni fra l'intensità macrosismica e PGA A.A. Gómez Capera (1) , D. Albarello (2) , P. Gasperini (3)
Recent Evolution and Seismicity of the Mediterranean Region, 1993
... AD: Adriatic block; AE: Aegea; AN: Anatolia; AR: Arabia; BA: Balearic basin; BB: Bay of Bisca... more ... AD: Adriatic block; AE: Aegea; AN: Anatolia; AR: Arabia; BA: Balearic basin; BB: Bay of Biscay; BS: Black Sea; CYA: Cyprus arc; Gf: Gloria fault; GM: Gibraltar-Morocco block; Ht: Hellenic trench; I: Iberia; PA: Pannonian basin; PSt: Pliny and Strabo trenches; RGs: Rhine Graben ...
... Brancato A., Gresta S., Sandri L., Selva J., Marzocchi W., Alparone S., Andronico D., Bonfort... more ... Brancato A., Gresta S., Sandri L., Selva J., Marzocchi W., Alparone S., Andronico D., Bonforte A., Caltabiano T., Cocina O., Corsaro RA, Cristofolini R., Di Grazia G., Distefano G., Ferlito C., Gambino S., Giammanco S., Greco F., Napoli ... Corresponding author: Dario Albarello Dept. ...
Building Knowledge for Geohazard Assessment and Management in the Caucasus and other Orogenic Regions, 2021
Bulletin of Earthquake Engineering, 2022
Author names/surnames found in reverse order and needs to be corrected as per original submission... more Author names/surnames found in reverse order and needs to be corrected as per original submission: first name: STEFANIA-last name (surname): FABOZZI first name: DARIO-last name (surname): ALBARELLO first name: ALESSANDRO-last name (surname): PAGLI-AROLI first name: MASSIMILIANO-last name (surname): MOSCATELLI.
La modernità ha delineato il futuro come spazio di libertà. Questo spazio è garantito dalla coesi... more La modernità ha delineato il futuro come spazio di libertà. Questo spazio è garantito dalla coesistenza di modelli previsionali legittimati da procedure che ne garantiscono la coerenza interna e sono corroborati da dati osservativi. Ma la coesistenza di modelli potenzialmente efficaci richiede anche una valutazione comparata che attribuisca opportuni valori di verosimiglianza agli scenari alternativi che questi modelli delineano. Sulla base di queste valutazioni, la comunità è chiamata a decidere quali modelli adottare attraverso una pratica politica capace di implementare scelte consapevoli dei vincoli che il paradigma scientifico pone e tenga contestualmente conto dei valori e dei desideri di quella comunità.
Building Knowledge for Geohazard Assessment and Management in the Caucasus and other Orogenic Regions, 2021
The possibility is here explored to use an ‘equivalent’ homogeneous configuration to simulate 1D ... more The possibility is here explored to use an ‘equivalent’ homogeneous configuration to simulate 1D seismic response of heterogeneous engineering-geological bodies when relatively weak seismic impedance contrasts (150 m/s) only exist above the seismic bedrock. This equivalent configuration is obtained by considering an equivalent Vs value the harmonic average of the actual Vs values and a linear combination of G/G 0 and D curves relative to the lithotechnical components present in the actual configuration. To evaluate feasibility of this approach, a wide set of numerical simulations was carried out by randomly generating subsoil layering including sequences of alternating thin layers of geotechnical units ( e.g., sands and clays) each characterized by a characteristic nonlinear curve. Outcomes of these simulations are compared with those provided by considering a single homogeneous layer characterized by equivalent nonlinear curves obtained as a weighted average of the original curves....
In 2015, the Seismic Hazard Centre (CPS) of the Istituto Nazionale di Geofisica e Vulcanologia (I... more In 2015, the Seismic Hazard Centre (CPS) of the Istituto Nazionale di Geofisica e Vulcanologia (INGV) was commissioned to engage and coordinate the national community with the aim of elaborating a new reference seismic hazard model, which is expected to be released in mid 2018. CPS outlined a roadmap to describe the main features of this complex endeavour, including the different scientific tasks, milestones and timelines. The scientific tasks focus their work on i) improving the quality and the accuracy of the input data (e.g. historical seismic catalogue, seismotectonic zonation, etc.); ii) building new earthquake rate models based on these new input data, iii) selecting the most proper ground motion prediction equations, iv) testing the overall seismic hazard model as well as each component; v) combining the results of the statistical testing phase and the outcome of an expert's elicitation session to assign a weight to each component of the final seismic hazard model. The ne...
Bulletin of the Seismological Society of America, 2021
ABSTRACTThis article focuses on the full exploitation of geological and economically viable geoph... more ABSTRACTThis article focuses on the full exploitation of geological and economically viable geophysical surveys for the seismic characterization of the shallow subsoil in the frame of microzonation studies in urban areas where economic resources for detailed seismic response analyses are scarce. In these conditions, the outcomes of inexpensive geophysical surveys (e.g., based on ambient vibration monitoring or surface-wave prospecting) must be fully exploited. To reduce the uncertainties related to these kinds of procedures, their joint interpretation in the light of geological evidence is mandatory. To this purpose, we propose the application of principal component analysis to combine the results of distributed single-station ambient vibration measurements (horizontal-to-vertical spectral ratio [HVSR] technique) to provide a preliminary zonation of the study area. The zones identified in this way are then characterized by considering the available geognostic boreholes, VS profiles ...
Geosciences, 2021
A first-order seismic characterization of Northern Apulia (Southern Italy) has been provided by c... more A first-order seismic characterization of Northern Apulia (Southern Italy) has been provided by considering geological information and outcomes of a low-cost geophysical survey. In particular, 403 single-station ambient vibration measurements (HVSR techniques) distributed within the main settlements of the area have been considered to extract representative patterns deduced by Principal Component Analysis. The joint interpretation of these pieces of information allows the identification of three main domains (Gargano Promontory, Bradanic Through and Southern Apennines Fold and Thrust Belt), each characterized by specific seismic resonance phenomena. In particular, the Bradanic Through is homogeneously characterized by low frequency (<1 Hz) resonance effects associated with relatively deep (>100 m) seismic impedance, which is contrasting corresponding to the buried Apulian carbonate platform and/or sandy horizons located within the Plio-Pleistocene deposits. In the remaining on...
Bulletin of the Seismological Society of America, 2019
In earthquake engineering, 'engineering bedrock' is regarded as a stiff material (i.e., rock or r... more In earthquake engineering, 'engineering bedrock' is regarded as a stiff material (i.e., rock or rock-like geological formation) that is characterized by a shear-wave velocity greater than a target value (e.g., 800 m/s; current Italian and European seismic codes). In the case of deep basins, the identification of engineering bedrock is problematic, as it can lie well below the penetration depth of most common prospecting methods (i.e., a few tens of meters). Moreover, the depth of engineering bedrock might not represent an effective proxy of the sedimentary thickness responsible for site amplification. The Po Plain sedimentary basin (northern Italy) is one of the deepest and widest worldwide, and it presents such problems. The aim of this work is to estimate the sedimentary thickness responsible for ground-motion amplification at medium and long periods in the Po Plain. Passive seismic prospecting methods based on ambient-vibration measurements using single-station and array configurations were considered to map 'seismic bedrock' depth. This corresponded to a marked seismic impedance contrast where the shear-wave velocity approached, or exceeded, 800 m/s. In the latter case, seismic and engineering bedrocks coincided. Our mapping will be useful for future site response assessments, numerical modeling of seismic-wave propagation, dynamic ground response analyses, and site-specific seismic hazard evaluation at the basin scale.
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Papers by Dario Albarello