The Fucino Basin, the largest tectonic basin within the Central Apennines orogen, is bounded by normal faults that have controlled the deposition of over 1 km of Pliocene-Quaternary continental deposits above a Messinian substratum. Conflicting interpretations from legacy seismic profiles have hindered a full understanding of the basin's stratigraphy, age, evolution, and fault systems, creating uncertainties for tectonic reconstructions, seismic response analysis and hazard assessment. To resolve these uncertainties, we acquired new high-resolution datasets through three complementary active-passive seismic surveys. These include seismic reflection profiles covering similar to 10 km, a nodal ambient noise campaign deploying 258 short-period nodes over 16 km2, preceded by two pilot array tests, and finally a basin-wide ambient noise survey comprising 1-hour recordings at 42 sites. Our analysis focused on the San Benedetto and Trasacco Faults-responsible for the 1915, M7.1, Marsica earthquake-and the main depocenter (the Bacinetto) associated with the San Benedetto Fault. This paper presents experimental setup, recorded data, and initial findings that provide new insights into basin stratigraphy, fault geometry, and spatial distribution of the fundamental resonance frequency (f0). The seismic reflection data show excellent imaging quality, resolution, and penetration exceeding 1 km. The Bacinetto hosts up to 850-900 m of continuous lacustrine succession and lower fluvio-lacustrine deposits that record sustained syn-sedimentary slip along the San Benedetto Fault from the Late Pliocene to Recent times. No evidence is found for significant synthetic or antithetic faulting beneath the depocenter, contradicting earlier structural models. The intra-basin Trasacco Fault forms a clear basement step and localized sediment thickening that tapers northwestward f0 varies from 1 to 2 Hz near the basin margins to similar to 0.2 Hz in the Bacinetto, reflecting progressive sediment thickening, whereas it varies abruptly across fault zones. f0 estimates from nodal and station data show good consistency.

This paper illustrates the activities of EMERSITO, an emergency task force of the Istituto Nazionale di Geofisica e Vulcanologia (INGV, Italy) devoted to site effects and microzonation studies during the seismic sequence that occurred close to the Adriatic coast in central Italy starting from 9 November 2022, following the Mw 5.5 mainshock localized in the sea. In particular, we describe the steps that led to the deployment of a temporary network of seismic stations in the urban area of Ancona, the main city of the Adriatic coastline. Data collected by the temporary Ancona network (identification code 6N; https://doi.org/10.13127/sd/qctgd6c-3a, EMERSITO Working Group, 2024) from November 2022 to the end of February 2023 have been preliminary analyzed with different techniques to characterize the deployment sites and are now available for further and detailed studies.

The ability to image the underground structures of volcanoes is limited by the precision, resolution and pene-tration depth of each single geophysical method. In order to improve the knowledge of specific volcanic edifices and to better understand the general behavior of structures, the use of a combination of methods is strongly recommended to exploit and maximize their complementary capabilities of resolution and penetration depths. In this work a large dataset of seismic and electromagnetic measurements has been used to provide a more detailed and improved geophysical image of the shallower portion of the northern sector of Ischia Island (Campania region, Italy), severely hit by the August 21, 2017 earthquake (Mw 3.9). We analysed data by using different methodologies: Horizontal-to-Vertical Spectral Ratio (HVSR), seismic array technique (f-k), polarization analysis and Time Domain ElectroMagnetic (TDEM) survey. These methods are sensitive in a different way to tectonic features, lithologies, layer geometry and fluid distribution. Thus, their combination is useful for studying sites with complex crustal structures such as Ischia island, which is characterized by a well-developed geothermal system linked to the presence of a shallow magmatic body. Results of our study provides detailed information of the physical properties of the subsoil through: 1) the spatial distribution of the amplification parameters of ground motion, showing frequency peaks below 1 Hz and/or between 1 Hz and 5 Hz; 2) the definition of the velocity models up to 600 m depth, with shear wave velocities ranging from 150 m/s for the shallower layers to 2500 m/s for the half space; 3) the recognition of the correlation between the principal fault structures and polarization directions of the noise wavefield, mostly oriented along EW and NE-SW directions; 4) the resistivity models of the first 80 m depth with high resistivity values of the shallow layers in the range 50-100 omega.m and low resistivity values of the bottom layers in the range 1-10 omega.m.

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.

<p>The role of fluids in the preparatory phase of major earthquakes and in the evolution of aftershocks and swarms in space and time is well-documented. In particular, numerous studies evidence the primary role that mantle-derived fluids play in the generation of large upper crustal earthquakes in extensional domains, where crustal-scale faults act as preferential hydraulic pathways.  </p><p>We focus on the Mefite D'Ansanto degassing site, the largest low-temperature non-volcanic CO<sub>2</sub> emission in the world, located at the northern tip of the Mw6.9 1980 Irpinia faults. The study area experienced strong historical earthquakes (1702, 1732 and 1930 M6+ earthquakes) but it is characterized by a relatively low background seismicity rate with respect to the nearby Sannio and Irpinia regions.    </p><p>To collect high-quality microseismicity data in this key sector of the southern Apennine extensional belt and investigate the relationship among seismicity, crustal fluids, and physical-hydraulic properties of the crust, we installed in July 2021 (up to May 2023) a temporary network composed of 10 stations equipped with short-period velocimeters (5 sec). The temporary network covers an area of approximately 30x30 km<sup>2</sup> surrounding the Mefite d’Ansanto site and integrates with the numerous permanent stations of the INGV and ISNet networks located at the boundary of the survey area. </p><p>Within the Mefite area, we also deployed a temporary seismo-acoustic dense array to study two CO<sub>2</sub> vents. The seismo-acoustic array is composed of 5 infrasonic stations equipped with IST-2018 broadband microphones developed by The ISTerre (Université Savoie Mont Blanc, France), in addition to one seismo-acoustic station equipped with a co-located digital broadband seismometers (120s). The array is positioned approximately at the vertices of a star, with an aperture of about 50 meters. The deployment lasted for 1 week at the end of May 2022, allowing us to sample the emission site during “dry” weather conditions. </p><p>We show first results of the analysis of seismicity recorded by the temporary network applying both standard (STA/LTA) detection algorithms or innovative enhanced techniques such as cross-correlation based <em>template-matching</em> algorithms and/or <em>Deep-Learning-Phase-Recognition</em> methods.</p><p>The activities are developed in the framework of the multidisciplinary project FURTHER (https://progetti.ingv.it/en/further).</p>

The Val d'Agri basin is one of the areas of highest seismic hazard in Italy. Moreover, widespread residential buildings with high seismic vulnerability, a water reservoir, and infrastructures related to hydrocarbon exploitation contribute to increasing the local seismic risk. The basin is several kilometers wide, about 400 m deep, and filled by continental, Quaternary sediments. In this paper we analyse earthquake weak ground motions and ambient noise measurements to investigate local site effects. Data were recorded by eight seismic stations deployed along a 7 km long transect that runs SW-NE across the central part of the basin. The stations operated for three years. Four stations were installed within the basin, two near its edges, and two outside on limestone outcrops. Good quality recordings from about eighty local and regional earthquakes (with average distance from the basin 400 km and 40 km respectively, and ML in the 1.2 - 6.5 range) evidence significant ground motion amplification both in the peak values and durations for the basin stations relative to the hard-rock one. Site effects have been investigated by computing: (1) standard spectral ratios with respect to the hard-rock station (H/Hrif), (2) singlestation H/V spectral ratios, (3) simplified 1-D and 2-D numerical modelling based on subsurface information. Frequency-time and particle motion analyses performed on earthquake data indicate that the observed ground motion amplifications cannot be fully explained by simple 1-D propagation effects, so we carried out several 2-D numerical simulations in order to better investigate the basin seismic response. The results evidence a role played by basin edge effects on the observed ground motion amplifications. Besides, the response of the basin is controlled by lateral heterogeneities between coarse cemented deposits filling the eastern depocenter and lowvelocity softer deposits widespread in the central-western sector.

We present a summary of seismological and geophysical investigations at Amatrice (Central Italy), a village seated on an alluvial terrace and severely stroke by the Mw 6.0 event of August 24th 2016. The high vulnerability alone could not explain the heavy damage (X-XI MCS), whereas the vicinity of the seismic source and the peculiar site effects should be claimed to understand the ground motion variability. After the first mainshock, we investigated the Amatrice terrace for microzonation purposes together with several Italian institutions (Priolo et al., Bull. Earthquake Eng. 2019). In particular: (i) we installed 7 seismic stations as a part of the 3A network (DOI: 10.13127/SD/ku7Xm12Yy9; Cara et al., Sci. Data 2019); we performed (ii) an extensive campaign of 60 single-station ambient noise measurements (downtown stations recorded also few earthquakes), and (iii) several 2D passive seismic arrays aimed at obtaining Vs profiles down to a depth of few tens of meters (Milana et al., Bull. Earthquake Eng. 2019). Earthquake recordings were used to empirically evaluate ground motion amplification effects through spectral ratio approaches, and noise data were collected for defining the spatial distribution of the resonance frequencies. Data analysis reveals a diffuse amplification effect that reaches its maximum values in downtown area with a resonant frequency (f0) of about 2 Hz. Seismic amplification is also characterized by spatial variation and directional amplification, mainly in downtown to the west side of the alluvial terrace, and related to both stratigraphic and topographic effects. This effect tends to decrease and almost vanishes in the central part of the terrace, and it increases again moving towards its eastern edge with a clear shift of f0 towards higher frequencies. Empirical transfer functions were then used to recover the ground motion that could have hit the historical center of Amatrice during the August 24th mainshock, through the convolution with the only record in the vicinity (IT.AMT station experienced a PGA of 0.87 g). The reconstructed peak values are much greater than expected from ground motion models, showing that detailed studies on local site response can largely modify the seismic hazard assessment.

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 August 2016, a magnitude 6.0 earthquake struck Central Italy, starting a devastating seismic sequence, aggravated by other two events of magnitude 5.9 and 6.5, respectively. After the first mainshock, four Italian institutions installed a dense temporary network of 50 seismic stations in an area of 260 km2. The network was registered in the International Federation of Digital Seismograph Networks with the code 3A and quoted with a Digital Object Identifier ( https://doi.org/10.13127/SD/ku7Xm12Yy9 ). Raw data were converted into the standard binary miniSEED format, and organized in a structured archive. Then, data quality and completeness were checked, and all the relevant information was used for creating the metadata volumes. Finally, the 99 Gb of continuous seismic data and metadata were uploaded into the INGV node of the European Integrated Data Archive repository. Their use was regulated by a Memorandum of Understanding between the institutions. After an embargo period, the data are now available for many different seismological studies.

Seismic traces in binary MiniSeed format recorded by the station MZ01. The daily records are separated in folders representing the channels: EHE.D, EHN.D, EHZ.D for the velocimetric data and HNE.D, HNN.D and HNZ.D for the accelerometric data. Velocimetric data are available from September 19, 2016 to October 14, 2016, whereas the accelerometric data are available up to November 25, 2016.

Seismic traces in binary MiniSeed format recorded by station MZ30. The daily records are separated in folders representing the channels: EHE.D, EHN.D, EHZ.D for the velocimetric data and HNE.D, HNN.D and HNZ.D for the accelerometric data. Both velocimetric and accelerometric data are available from October 27, 2016 to November 17, 2016.

Seismic traces in binary MiniSeed format recorded by station MZ18. The daily records are separated in folders representing the channels: EHE.D, EHN.D, EHZ.D for the velocimetric data and HNE.D, HNN.D and HNZ.D for the accelerometric data. Both velocimetric and accelerometric data are available from September 27, 2016 to October 26, 2016.

Seismic traces in binary MiniSeed format recorded by station MZ29. The daily records are separated in folders representing the channels: EHE.D, EHN.D, EHZ.D for the velocimetric data and HNE.D, HNN.D and HNZ.D for the accelerometric data. Both velocimetric and accelerometric data are available from October 27, 2016 to November 17, 2016.

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.

Rapporto Tecnico n°1 della task force operativa EMERSITO++ (INGV) che descrive le campagne sismiche ed elettromagnetiche condotte nei comuni di Casamicciola Terme e di Lacco Ameno a seguito del terremoto di Ischia del 21 Agosto 2017.

We carried out a vibration study experiment on a masonry building in the town of Ariano Irpino, southern Italy, using six-channel stations equipped with three-component velocity-transducers and accelerometers and running in continuous modality from January 2006 to December 2007. The analysis of weak motions from several local earthquakes, together with the 3D numerical modelling of the structure, allowed us to identify the first three vibration modes of the target building. Therefore, we checked the validity of ambient noise data to determine the vibration frequencies of buildings. The analysis tools based on earthquake and ambient noise data were conventional, i.e. spectral ratios between homologous components of stations at high floors in the building with respect to a station installed at the basement, and single-station spectral ratios between horizontal and vertical components. The indications derived from earthquakes and ambient noise result in a satisfactory agreement for frequencies between 1 and 20 Hz when using recordings characterized by low levels of amplitude, both for cultural and meteorological noise. In contrast, when the wind speed increases (above 20 km/h, approximately) seismic noise shows an excess of horizontal vibrations at low frequencies (below 2 Hz). These extra-amplitudes are not related to the seismic input vertically incident to the basement, but are probably due to the lateral action of the wind on the building. In contrast anthropic activities do not affect considerably the trend of spectral ratios in the range of frequencies that include the first modes of vibration of the building, even at high noise level.

347 sIte ChArACterIzAtIon of the nAtIonAl seIsmIC network of ItAly: results At fIVe CAse studIes G. Di Giulio1, P. Bordoni2, G. Cultrera2, M. Vassallo1, D. Famiani2, G. Milana2, F. Cara2, A. Mercuri2, M. Pischiutta2, E. D’Alema3, S. Lovati3, C. Mascandola3, M. D’Amico3, F. Pacor3, C. Felicetta3, M. Massa3, L. Luzi3, R. Puglia3, A. Fodarella4, S. Pucillo4, R. Cogliano4, G. Riccio4, D. Di Naccio1, S. Amoroso1, L. Cantore1, M. Cattaneo5, C. Ladina5, R. Bonomo6, C. D’Ambrogi6, M. D’Orefice6, P. Di Manna6, D. Fiorenza6, R.M. Gafà6, G.M. Monti6, M. Roma6, L. Vita6 1 Istituto Nazionale di Geofisica e Vulcanologia, L’Aquila, Italy 2 Istituto Nazionale di Geofisica e Vulcanologia, Roma, Italy 3 Istituto Nazionale di Geofisica e Vulcanologia, Milano, Italy 4 Istituto Nazionale di Geofisica e Vulcanologia, Grottaminarda, Italy 5 Istituto Nazionale di Geofisica e Vulcanologia, Ancona, Italy 6 ISPRA Sistema Nazionale Protezione Ambiente, Roma, Italy