Massa, Marco

The present work would like to illustrate a new concept of multiparametric stations to characterize the crustal fluids-tectonic interaction in specific geological contexts. The dynamics of crustal fluids in relation to tectonics is a complex and sometimes intricate issue. Several factors act and mutually influence themselves, so that in each tectonic and geological context they follow a specific behavior, and a comprehensive cause-effect rule is hard to find. Changes in water chemistry and levels and in soil flux regimes (e.g., CO2, CH4, radon) are just a few examples well documented in the literature as being pre-, co- and post-seismic modifications as well as being markers of the local tectonic stress acting in the crust. A regional study combined with a long-lasting multiparametric monitoring is needed to prepare to a seismic sequence in a given place. The field infrastructure was set up starting from the end of 2021, and multiparametric stations have been installed in correspondence of active seismogenic sources initially located in Northern Italy. Data are transmitted in real-time and archived in an ad hoc developed relational database. Monitoring is mainly focused on groundwater parameters (water level, temperature, and electrical conductivity) of aquifers showing distinct degrees of confinement and lithologies. Sites are also equipped of meteorological sensors (pressure, temperature, rain, humidity, wind speed and direction), radon sensors and surface and borehole seismic stations providing accelerometric and velocimetric data. A mud volcano field is also monitored and holds the installation of a permanent CO2 soil flux station. A statistical analysis working flow is also proposed for a preliminary evaluation of the acquired time-series. In particular, a couple of tools to detect, and thus filter, anthropogenic and meteorological effects on a groundwater level series is described. We wish to provide a model of approach to analogous study cases in other potentially seismic areas.

Il giorno 9 novembre 2022, alle 06:07:24 UTC (07:07:24 ora locale) un terremoto di magnitudo momento (MW) pari a 5.5 ha interessato la Costa Marchigiana Pesarese (Pesaro Urbino). A causa della magnitudo del mainshock e del livello di danneggiamento riscontrato, l’INGV ha attivato il gruppo operativo EMERSITO (http://emersitoweb.rm.ingv.it/index.php/it/), il cui obiettivo è di svolgere e coordinare le campagne di monitoraggio per studi di effetti di sito e di microzonazione sismica. Il gruppo operativo ha provveduto all’installazione di una rete sismica temporanea nel territorio del comune di Ancona; molte delle stazioni sismiche sono state installate in corrispondenza di edifici pubblici (scuole, Tribunale, Marina Militare, strutture religiose), grazie alla collaborazione con la sede INGV di Ancona, con la Protezione Civile Regione Marche, la Marina militare e la Capitaneria di Porto. Nel presente Report vengono brevemente riassunte le attività già svolte (si vedano i Report precedenti), discusse le analisi dei dati raccolti e mostrati alcuni risultati preliminari riguardanti la rete sismica temporanea. Sono state effettuate le seguente analisi preliminari: qualità delle registrazioni; rapporti spettrali su rumore sismico ambientale e su una selezione di terremoti registrati; analisi della dipendenza dei risultati dei rapporti spettrali dalla direzione del moto sismico (polarizzazione del segnale); calcolo dei meccanismi focali su alcuni eventi selezionati. Infine è stato prodotto un modello geologico semplificato, inclusivo delle informazioni derivanti dalle indagini geologiche e geofisiche preesistenti, che fornisce una chiave interpretativa dei risultati ottenuti.

Following the Mw 6.0 Amatrice earthquake on 24 August 2016 in central Italy, the Emersito task force of the Istituto Nazionale di Geofisica e Vulcanologia installed a temporary seismic network focusing on the investigation of amplification effects at municipalities located on topographic reliefs. Fourteen stations were installed at three sites: Amandola, Civitella del Tronto, and Montereale. During the operational period, stations recorded about 150 earthquakes with Mw up to 4.7. Recorded signals were analyzed calculating the horizon- tal-to-vertical spectral ratios at single station, using both ambient noise and earthquake waveforms, as well as standard spectral ratios (SSRs) to a reference site. To robustly estimate site amplification at each station of the site amplification effect at each station, the influence of backazimuth and epicentral distance is investigated. With the aim of reproducing the observed amplification pattern, 2D numerical simulations were performed on a section orthogonal to the topography major axis, constrained through in situ geological investiga- tions and geophysical surveys. Although at Montereale site no clear amplification effects were observed, at Amandola site, all stations on the relief consistently detected significant peaks at about 4 Hz and along N120–150 azimuth. At Civitella del Tronto, a proper reference station is missing, implying a misleading of site response evaluation in terms of SSRs. Moreover, even if all stations show amplification in the frequency band 1–3 Hz, the direction of the maximum amplification varies from northeast to northwest. At the three sites, obser- vations were successfully reproduced by 2D numerical models, the latter suggesting that topography alone cannot reproduce data, and the interplay with subsoil velocity structure is needed to produce a clear amplification effect. We conclude that according to the previous articles, rather than the sole topography convex shape, the geophysical structure has often a predominant role in controlling the observed amplification pattern on topography.

Il giorno 9 Novembre 2022, alle 06:07:24 UTC (07:07:24 ora locale) un terremoto di magnitudo momento (MW) pari a 5.5 ha interessato la Costa Marchigiana Pesarese (Pesaro Urbino). A causa della magnitudo del mainshock e del livello di danneggiamento riscontrato, l’INGV ha attivato il gruppo operativo EMERSITO (http://emersitoweb.rm.ingv.it/index.php/it/), il cui obiettivo è di svolgere e coordinare le campagne di monitoraggio per studi di effetti di sito e di microzonazione sismica. Nel presente Report sono descritte le attività portate avanti nei giorni successivi al Report n.1 (Gruppo Operativo EMERSITO (2022) - Rapporto n.1 preliminare sulle attività svolte dal gruppo operativo Emersito a seguito dell’evento sismico Costa Marchigiana Pesarese Mw 5.5 del 9/11/2022. Pubblicato il 9/11/2022, URL: http://hdl.handle.net/2122/15783): reperimento di informazioni geologiche e geofisiche, di studi su effetti di sito già osservati nella zona colpita e della microzonazione sismica disponibile. In base ai dati recuperati, è stata pianificata l’installazione di una rete sismica temporanea di circa 10 stazioni nell’area urbana di Ancona, capoluogo di provincia e importante zona portuale, caratterizzata da livelli alti di PGA e che ha subito danni diffusi e evacuazioni, caratterizzata da elevate eterogeneità litologiche e morfologiche. Sono stati inoltre analizzati i dati registrati durante l’attuale sequenza sismica ed acquisiti dalle stazioni sismiche permanenti (IV e IT) e temporanee (GO SISMIKO) presenti nell’area, per verificare la presenza di effetti di sito nelle registrazioni.

Il giorno 9 Novembre 2022, alle 06:07:24 UTC (07:07:24 ora locale) un terremoto di magnitudo momento (MW) pari a 5.5 ha interessato la Costa Marchigiana Pesarese (Pesaro Urbino). A causa della magnitudo del mainshock e del livello di danneggiamento riscontrato, l’INGV ha attivato il gruppo operativo EMERSITO (http://emersitoweb.rm.ingv.it/index.php/it/), il cui obiettivo è di svolgere e coordinare le campagne di monitoraggio per studi di effetti di sito e di microzonazione sismica. Durante le prime fasi di un’emergenza sismica, l’attività principale del gruppo operativo EMERSITO consiste, attraverso la costituzione di gruppi di lavoro, nel reperimento delle informazioni geologiche e geofisiche, nell’analisi dei dati sismici esistenti, nella pianificazione di misure sismologiche e geofisiche ed in attività propedeutiche alla microzonazione sismica. Nel caso specifico della sequenza sismica della Costa Marchigiana Pesarese: - sono state reperite informazioni di letteratura sugli effetti di sito già osservati nella zona colpita, sulla cartografia geologica e sulla microzonazione sismica disponibile; - sono state reperite le informazioni di caratterizzazione dei siti delle stazioni sismiche permanenti presenti nell’area (http://itaca.mi.ingv.it/ItacaNet_31 e http://crisp.ingv.it) e sono stati rianalizzati alcuni dati disponibili (http://eida.ingv.it/). - è stata pianificata l’installazione di una rete sismica temporanea nella zona colpita dal terremoto, nei comuni di Ancona e Senigallia. La scelta delle aree è stata guidata principalmente dalla prossimità con l’area epicentrale, dalla disponibilità di studi di microzonazione sismica e di carte geologiche a differenti scale di rappresentazione, dalla distribuzione dei parametri di scuotimento del suolo e della sismicità in tempo reale.

The present work is part of the 2015 ART-IT project (Early Earthquake Alert in Italy). Its main purpose is the estimation of the PRESTo system [PRobabilistic and Evolutionary early warning SysTem, Iannaccone et al., 2010; Satriano et al., 2011] performance through an ad hoc calibration of the software configuration parameters using only the accelerometric networks installed in an area of Central Italy, selected as test site. The correct operation of an early warning system could be used for a more correct and effective management of a seismic emergency from the first seconds after the occurrence of a strong earthquake, allowing to adopt sudden actions to reduce the exposure and, consequently, the seismic risk. To evaluate the performance of the software, it is necessary to carry out an a priori calibration phase of the configuration parameters in order to guarantee the best performance in terms of seismic event detection and reliability in the estimation of hypocentral parameters. The tests were carried out by means of a series of recorded waveforms simulations considering a selected catalogue of earthquakes with a magnitude range between 3.9 and 5.4, occurred in the Amatrice-Norcia area, with a magnitude range between 3.9 and 5.4, occurred in the Amatrice-Norcia area, with particular focus on the seismic sequence of January 2017.

In this paper, we present the work carried out to characterize the spatial variability of seismic site response related to local soil conditions in the city of Milan and its surroundings, an area with ~3 million inhabitants and a high density of industrial facilities. The area is located at the northwestern end of the Po Plain, a large and deep sedimentary basin in northern Italy. An urban-scale seismo-stratigraphic model is developed based on new passive and active seismic data, supported by the available geological data and stratigraphic information from shallow and deep vertical wells. In particular, 33 single-station and 4 ambient-vibration array measurements are acquired, together with 4 active multichannel analyses of surface waves (MAWS). To estimate the resonant frequencies of the sediments, the horizontal to vertical spectral ratio technique (HVSR) is applied to the ambient-vibration recordings, whereas to determine the Rayleighwave dispersion curves from the passive array, the data are analysed using the conventional frequency-wavenumber, the modified spatial autocorrelation and the extended spatial autocorrelation (ESAC) techniques. The array data are used to determine the local shear wave velocity profiles, VS, via joint inversion of the Rayleighwave dispersion and ellipticity curves deduced from the HVSR. The results from HVSR show three main bands of amplified frequencies, the first in the range 0.17–0.23 Hz, the second from 0.45 to 0.65 Hz and the third from 3 to 8 Hz. A decreasing trend of the main peaks is observed from the northern to the southern part of the city, allowing us to hypothesize a progressive deepening of the relative regional chrono-stratigraphic unconformities. The passive ambient noise array and MASW highlight the dispersion of the fundamental mode of the Rayleigh-wave in the range 0.4–30 Hz, enabling to obtain detailed Vs. profiles with depth down to about 1.8 km. The seismo-stratigraphic model is used as input for 1D numerical modelling assuming linear soil conditions. The theoretical 1D transfer functions are compared to the HVSR curves evaluated from both ambient noise signals and earthquake waveforms recorded by the IV. MILN station in the last 10 years.

The eruption of the volcano Hunga Tonga-Hunga Ha‘apai on Jan 15, 2022, 04:14:54 UTC, was such energetic that instruments observed different physical phenomena all over the globe. In Italy, the Istituto Nazionale di Geofisica e Vulcanologia (INGV), who is continuously operating different kinds of monitoring networks, as e.g., the Italian Seismic Network (ISN), micro-barometric and infrasonic stations for monitoring the active volcanoes, ionospheric monitoring network (GNSS and ionosonde), recorded seismic, acoustic and electromagnetic signals originated by this exceptional event. The blast wave generated by the volcanic explosion of Hunga Tunga was recorded by the micro-barometric and infrasound stations installed at Phlegrean Fields (PF), at Stromboli volcano and on Mt. Etna. The first arrival was recorded at ~20:00 UTC, after travelling along the “short” great circle (17600 km), was succeeded by a second onset, about 3:40 h later, arriving at PF from the opposite direction. The mean propagation velocity in both directions was calculated as 310 m/s. The stations of the Etna Radio Observatory (ERO) are also equipped with micro-barometers, measuring the atmospheric pressure at a sampling rate of 5 min. The first group of atmospheric shock waves was recorded in the evening of Jan 15, 2022, while 36 hours later the ERO-stations observed a second signal after having completed the second orbit. The magnitude of M5.7 of the Hunga Tonga eruption was strong enough to record core phases (PKIKP, PKP), surface reflection of mantle phases (PP, SS), as well as Rayleigh and Love waves, at many stations of the ISN. The atmospheric waves generated by the eruption generated Travelling Ionospheric Disturbances in the ionosphere detected as disturbances in the Total Electron Content calculated by using GNSS data acquired by the GNSS network of INGV and variations of the ionospheric peak layer parameters (foF2, hmF2), recorded by the ionosonde installed on the Italian territory by INGV.

We present the Istituto Nazionale di Geofisica e Vulcanologia Strong‐Motion Data‐quality (ISMDq)—a new automatic system designed to check both continuous data stream and event strong‐motion waveforms before online publication. The main purpose of ISMDq is to ensure accurate ground‐motion data and derived products to be rapidly shared with monitoring authorities and the scientific community. ISMDq provides data‐quality reports within minutes of the occurrence of Italian earthquakes with magnitude ≥3.0 and includes a detailed daily picture describing the performance of the target strong‐motion networks. In this article, we describe and discuss the automatic procedures used by ISMDq to perform its data‐quality check. Before an earthquake, ISMDq evaluates the selected waveforms through the estimation of quality indexes employed to reject bad data and/or to group approved data into classes of quality that are useful to quantify the level of reliability. The quality indexes are estimated based on comparisons with the background ambient noise level performed both in the time and frequency domains. As a consequence, new high‐ and low‐noise reference levels are derived for the overall Italian strong‐motion network, for each station, and for groups of stations in the same soil categories of the Eurocode 8 (Eurocode 8 [EC8], 2003). In absence of earthquakes, 24 hr streaming of ambient noise recordings are analyzed at each station to set an empirical threshold on selected data metrics and data availability, with the goal to build a station quality archive, which is daily updated in a time span of six months. The ISMDq is accessible online (see Data and Resources) from August 2020, providing rapid open access to ∼10,000 high‐quality checked automatically processed strong‐motion waveforms and metadata, relative to more than 160 Italian earthquakes with magnitude in the 3.0–5.2 range. Comparisons between selected strong‐motion data automatically processed and then manually revised corroborate the reliability of the proposed procedures.