Latorre, Diana

It is well known that in the geosciences (as in all STEM disciplines), the percentage of women in top positions decreases in favor of men, despite comparable academic careers and, sometimes, even better results for women. The authors of this contribution hold managerial roles in preparing and managing seismic and tsunami emergencies at INGV. It has been a long journey, but it is now a positive reality. But it has sometimes been different! Since its establishment in 1999, the INGV has undergone significant growth and transformation. De Lucia et al. in 2021 [1] analyzed gender diversity within the organization, revealing that the workforce comprised 38% female and 62% male. While these proportions have remained relatively stable over subsequent years, nuances emerge when examining gender distribution with higher representation of women in administrative roles and men in technical positions. What is slowly changing in recent years is the presence of women in research and managerial leadership positions. Notably, between 2016-2020, a woman served as General manager and, since 2017, one of the three Department Directors (Environment, Earthquakes and Volcanoes) is a woman. Currently, 4 out of the 10 Directors of the INGV Offices are women, reflecting a positive trend towards gender parity in leadership roles. Additionally, both the recently elected INGV members of the Scientific Council are women, underscoring the growing influence of female voices in shaping scientific discourse and decision-making. In the present day, an increasing number of women fulfill pivotal roles across research, technical, and administrative realms, actively contributing to coordination and leadership. Notable instances include women actively engaged in the preparation and execution of seismic, volcanic and tsunami emergency protocols. Their responsibilities encompass crucial tasks and providing support services for emergency response teams (including operational rooms for seismic, volcanic, and tsunami surveillance, network monitoring infrastructures, or emergency response teams). In this contribution, the authors recount their experiences.

La revisione da parte degli analisti del BSI della sismicità registrata in Italia dal 1 settembre al 31 dicembre 2022 ha riguardato tutti i terremoti di magnitudo M≥1.5, mentre i parametri dei terremoti di magnitudo inferiore a tale soglia sono quelli calcolati in tempo reale, nella SALA DI SORVEGLIANZA SISMICA DI ROMA. I terremoti più forti (M≥3.5) e pochi altri di particolare interesse [vedi Marchetti et al., 2016, DOI: 10.4401/ag-6116], sono stati revisionati dagli analisti del BSI, mediamente nelle 24 ore successive al loro accadimento.

La revisione da parte degli analisti del BSI della sismicità registrata in Italia dal 1 gennaio al 30 aprile 2023 ha riguardato tutti i terremoti di magnitudo M≥1.5, mentre i parametri dei terremoti di magnitudo inferiore a tale soglia sono quelli calcolati in tempo reale, nella SALA DI SORVEGLIANZA SISMICA DI ROMA. I terremoti più forti (M≥3.5) e pochi altri di particolare interesse [vedi Marchetti et al., 2016, DOI: 10.4401/ag- 6116], sono stati revisionati dagli analisti del BSI, mediamente nelle 24 ore successive al loro accadimento.

On September 18, 2023, an earthquake with a magnitude of Ml=4.8 (Mw=4.9) occurred a few kilometers SW of Marradi (FI) at a depth of about 8 kilometers. The computed TDMT solution of the mainshock suggests a normal fault oriented NW-SE (Scognamiglio et al., 2006). The earthquake, preceded by a foreshock with a magnitude of Ml=3.3 (Mw=3.4), triggered a seismic sequence characterized, in the first two months, by approximately 700 aftershocks localized by the staff on duty in the Seismic Monitoring Room of the INGV in Rome, including 6 events with a magnitude of Ml≥3.0 occurred in the first two days. The sequence occurred in a high seismic hazard region. The two closest historical earthquakes occurred in the Mugello area about 30 km SW of Marradi (and about 25 km north of Florence): one, whose magnitude (Mw) is estimated to be about 6.0, occurred on June 13, 1542 while the other with estimated magnitude (Mw) of about 6.4 occurred on June 29, 1919. The second one is among the strongest (most significant) Italian earthquakes of the 20th century, and also one of the strongest known to date with its epicentre in the northern Apennines. The affected area was that of Mugello, with extensive damage both in the province of Florence and on the Romagna side of the Apennines. The analysts of the BSI (Italian Seismic Bulletin) reviewed the initial three days of the sequence, paying special attention to the hours directly following the mainshock. The BSI work mainly consists in revising the picking of P and S phases and assigning them appropriate weights, retrieving previously unused phases, and evaluating the maximum amplitudes necessary for calculating the value of Ml. The latter is a critical aspect of the initial phases of a seismic sequence; in fact, the occurrence of events is very close in time, making it challenging to estimate the maximum amplitudes and, consequently, the magnitude automatically. Through this analysis, they have identified an earthquake with a magnitude of Ml=3.4, occurring approximately one minute after the mainshock and overlooked during the surveillance service. Furthermore, a comprehensive effort to recover smaller seismic events not initially analyzed in the Seismic Monitoring Room resulted in the localization of 498 earthquakes, nearly a 30% increase within the first three days. In Figure 1(a-d), hypocentral parameters and time readings of the 352 earthquakes detected in the Seismic Monitoring Room have been compared with those of the same events revised by the BSI. It is evident as both the horizontal and vertical errors, as well the seismic gap associated with the location decrease for the dataset analyzed from the BSI, while the number of P and S phases increases for the same dataset. Subsequently, the events revised from BSI were initially relocated by applying the NonLinLoc code (Lomax et al., 2000) using a 1D regional velocity model from Pastori et al. (2019). Following this, a double-difference technique (Waldhauser and Schaff, 2008) was applied to improve the geometries of the activated structures (see Figure 2). Concomitantly, an analysis using the template matching technique was applied, for the period from September first to October 10th, to identify events overlooked by the Earthworm system in the Seismic Monitoring Room. The results are shown in Figure 3. It was found that the number of detections increased by approximately 60%. Furthermore, the figures 3c and 3d put in evidence as the larger number of new detected earthquakes is characterized by lower magnitude. This result highlights the value of integrating this type of analysis to complement the efforts of the Italian Seismic Bulletin (BSI).

Nel 2018 è stato avviato il progetto FOCUS - Fiber Optic Cable Use For Seafloor Studies Of Earthquake - coordinato da Marc-André Gutscher del Laboratoire Géosciences Océan dell’Università di Brest, in Francia. Questo progetto indaga la sismicità e la struttura crostale del Mar Ionio attraverso l’analisi e l’interpretazione di dati raccolti da strumentazione sottomarina e da reti di monitoraggio disponibili o appositamente installate nelle zone di costa. In tale contesto, l’Osservatorio Nazionale Terremoti (ONT) e l’Osservatorio Etneo (OE), entrambe Sezioni dell’Istituto Nazionale di Geofisica e Vulcanologia (INGV), e il Laboratorio di Sismologia dell'Università della Calabria (UniCal), hanno contribuito al progetto con l’installazione di una rete sismica temporanea lungo la costa ionica calabro-siciliana a integrazione della rete permanente presente nell’area dello Stretto di Messina. La rete temporanea, costituita da 13 stazioni, ha acquisito dal mese di dicembre 2021 al mese di giugno 2023. Nel gennaio 2022, i partner internazionali del progetto FOCUS hanno installato una rete temporanea di sismometri OBS e sensori di pressione per fondali marini. La grande quantità di dati raccolta e la loro integrazione, consentirà di migliorare il monitoraggio sismico e le conoscenze relative alla struttura terrestre dell’area con particolare attenzione alle strutture sismogenetiche con un dettaglio mai raggiunto fino a ora. Tutte le istituzioni coinvolte in FOCUS collaborano per l’acquisizione e l’elaborazione dei dati, l’imaging dell’interno della Terra attraverso l’utilizzo di tecniche avanzate, l’interpretazione e la modellazione dei dati. Il presente lavoro descrive la progettazione, la realizzazione e la gestione della rete temporanea a terra definita FXland, fornendo indicazioni relative sul suo generale funzionamento e sulle caratteristiche del dataset acquisito.

The INGV is the operational center for earthquake monitoring in Italy, https://www.ingv.it/en/monitoraggio-e-infrastrutture/sorveglianza/servizio-di-sorveglianza-sismica, it operates the Italian National Seismic Network and other networks at different scales and is a primary node of EIDA for archiving and distributing seismic recordings. INGV provides earthquake information to the Department of Civil Protection and to the public. In the frame of the FOCUS (Fiber Optic Cable Use for seafloor studies of earthquake hazard and deformation) project, https://www.geo-ocean.fr/Recherche/Projets-de-Recherche/ERC-FOCUS, we deployed a temporary seismic network, FXLand (1J), for a passive seismological experiment to record regional seismicity and teleseismic events. This experiment aims to improve the detection of seismicity; the accuracy of earthquake locations, and to define the crustal structure of the region. The seismicity in the Ionian area is possibly the result of two types of tectonic activity at different depths: a gently NW dipping subduction interface of the Calabrian subduction zone, and the strike-slip fault systems in the Ionian Sea, well expressed in the morpho-bathymetry and observed in previous seismic profiles.

Introduction In November 2022 a seismic sequence occurred in the Marche offshore, about 29 km from the coast and the city of Fano. The sequence started on November 9 (06:07:25 UTC) with a ML=5.7 earthquake (Mw=5.5 from TDMD computation, Scognamiglio et al., 2006), immediately followed by a ML=5.2 earthquake (06:08:29 UTC) located about 8 km to the south. The two mainshocks activated a seismic sequence with about 400 aftershocks lasting the first week, 13 of them with ML>= 3.5 (Fig. 1). Few hours after the occurrence of the mainshock, the BSI (“Bollettino Sismico Italiano”) working group started to manually analyze P and S phase arrival times and seismogram amplitudes of earthquakes with magnitude ML>= 3.5 recorded by the the Italian National Seismic Network (Rete Sismica Nazionale, hereafter RSN) in order to better constrain hypocenter locations previously provided by the seismic surveillance room of the INGV in Rome for rapid communication to the Italian Civil Protection (Dipartimento Protezione Civile, DPC). Later, the BSI working group analyzed the seismicity of the sequence of the first weeks of seismic activity by revising hypocentral parameters of more than 500 events. The 2022 Marche offshore sequence took place along the Adriatic outer front of the northern Apennines in central Italy. Offshore seismic reflection profiles image a shallow thrust-and-fold system striking WNW–ESE to NNW–SSE. Along the coastal Adriatic area, active blind thrusts deform Plio-Quaternary siliciclastic turbidites that are few hundreds of meters to more than 2 km thick in correspondence of ramp anticlines and synclines, respectively. In a recent work, through the analysis of high-quality background seismicity data, De Nardis et al. (2022) identified two lithospheric-scale active thrusts deepening westward under the Adriatic outer front from upper- to lower-crustal depths. These new data support previous thick-skinned interpretations of seismic commercial profiles and CROP03 deep reflection data (Lavecchia et al., 2003). Focal mechanisms of weak to moderate (ML < 4.8) local earthquakes occurred between 2009-2017 at upper- to deep-crustal depths show prevailing reverse and reverse/oblique solutions (De Nardis et al., 2022) and subordinate strike-slip faulting (Mazzoli et al., 2014). The analysis of the 2022 Marche offshore sequence opens again the discussion on the uncertainties related to the hypocenter locations of earthquakes that occur in the Adriatic offshore domain (e.g., Di Stefano et al., 2022) and the limits of our present capability to provide an accurate seismotectonic interpretation of the instrumental seismicity in this region. Actually, the 2022 sequence area is only covered on land by RSN, with the closest seismic station located at about 28 km from the epicentral location of the mainshock. The particular geometry of the network along the Italian coast makes it difficult to correctly constrain hypocenter locations compared with other regions of Italy. Taking into account this configuration, although the INGV is able to obtain coherent earthquake information for Civil Protection purposes into the limits of the communication threshold, we note that data provided by the seismic surveillance room in terms of both seismic phase readings of arrival times for hypocenter location and waveform amplitudes for magnitude computation need to a more accurate analysis if the main goal is the correct reconstruction of the active structures involved in the sequence. This analysis should include a) a careful revision of the arrival time pickings to reduce the errors due to seismic phase misinterpretations, b) an accurate study to constrain earthquake locations with appropriate velocity models, and c) the hypocenter solution assessment through adequate tests that define which information can be inferred from earthquake location results. Data analysis and phases interpretation Through the interpretation of the seismic records, the BSI analysts have identified refracted first arrivals of P and S phases at epicentral distances of about 60 km, smaller than those expected for Pn/Sn refracted phases at the Moho discontinuity (e.g., Di Stefano and Ciaccio, 2014) whose arrivals should be observed at distances of about 90-100 km in this area. Since possible systematic misinterpretation of P and S arrivals can strongly affect the correct hypocenter locations, we have carefully revised the phase pickings provided by the INGV surveillance room by discriminating direct from refracted phases at stations located at distances greater than 60 km. This is mainly important for interpretation of weak S refracted phases that are often hidden into the arrivals after the P phase. We have taken into account these characteristics in the earthquake location process by only using clear direct/refracted S phases in our inversion procedure. The comparison of the ML>= 3.5 hypocenter locations performed by the BSI and the INGV surveillance room (Figs. 1 and 2) shows how an accurate analysis of the pickings is necessary to obtain robust earthquake locations for seismotectonic interpretation: even using the same hypocenter location code and velocity model, we observe that the mislocation of the hypocenters in this area can range from few to about 10 kilometers (Fig. 1) while the formal errors are strongly reduced after the BSI picking revision (Fig. 2) The velocity model issue Events location in the Adriatic Sea suffers from the lack of a specific velocity model for the seismic sequence area. The use of inadequate velocity parameters during the location process can introduce systematic errors, which may result in incorrect seismotectonic interpretations. We therefore built and tested different velocity models from both available geophysical data and our inversion of the velocity structure using the arrival time readings revised by the BSI working group. In order to define deterministic 1D models suitable for earthquake location (Vp and Vp/Vs), we integrated sonic logs from local deep wells (ViDEPI Project, 2005) with literature data that include: seismic commercial profiles, deep seismic refraction surveys, the CROP03 crustal profile, Receiver Function and regional seismic tomography models, Vp/Vs reference values for mid- and lower-crustal crystalline rocks (Coward et al., 1999; Ponziani et al., 1995; Lavecchia et al., 2003; Spada et al., 2013; Di Stefano et al., 2009, Christiansen and Mooney, 1993). In order to obtain the velocity structure from our revised dataset, we first determined the Vp/Vs ratio by using the arrival time pickings of selected P and S phases. The mean velocity ratio Vp/Vs was computed through the cumulative Wadati diagram. Then, by collecting all the a priori available information regarding the structure of Adriatic Sea (velocities, layer thicknesses and Moho depth), we applied the VELEST software (Kissling, 1995) to compute a new 1D velocity model for earthquake location. Conclusions In this work we present our first analyses of the sequence and the accurate study of the velocity models that we obtained from both a revision of available data and the inversion of arrival time pickings analyzed by the BSI analists. Moreover, we will discuss our preliminary earthquake locations with a particular attention to resolution analysis and hypocenter location assessment.

La revisione da parte degli analisti del BSI della sismicità registrata in Italia dal 1 maggio al 31 agosto 2022 ha riguardato tutti i terremoti di magnitudo ML≥1.5, mentre i parametri dei terremoti di magnitudo inferiore a tale soglia sono quelli calcolati in tempo reale, nella SALA DI SORVEGLIANZA SISMICA DI ROMA. I terremoti più forti (ML≥3.5), e pochi altri di particolare interesse [vedi Marchetti et al., 2016, DOI: 10.4401/ag- 6116], sono stati revisionati dagli analisti del BSI, mediamente nelle 24 ore successive al loro accadimento.

La revisione da parte degli analisti del BSI della sismicità registrata in Italia dal 1 gennaio al 30 aprile 2022 ha riguardato tutti i terremoti di magnitudo ML≥1.5, mentre i parametri dei terremoti di magnitudo inferiore a tale soglia sono quelli calcolati in tempo reale, nella SALA DI SORVEGLIANZA SISMICA DI ROMA. I terremoti più forti (ML≥3.5), e pochi altri di particolare interesse [vedi Marchetti et al., 2016, DOI: 10.4401/ag- 6116], sono stati revisionati dagli analisti del BSI, mediamente nelle 24 ore successive al loro accadimento.

We have built a complete catalog of three-dimensional (3D) hypocenter locations of earthquakes recorded in Italy from 1981 to 2018. Our catalog includes more than 420,000 events relocated by inverting a newly integrated dataset of ~5.0 million P and ~ 3.5 million S wave arrival times recorded by the Italian National Seismic Network and other permanent seismological networks operating in Italy. Available magnitudes are associated with earthquake locations from the most recent datasets and bulletins of Italian seismicity. Earthquakes are located in an updated 3D tomographic model of Italy obtained by including the Moho discontinuity and the seismic velocities of the Ionian subduction zone. We used a probabilistic, non-linear earthquake location code which provides complete information of the hypocenter solution uncertainties. Quality estimators of earthquake locations are analyzed a posteriori with an original criterion for a quantitative classification of the results, allowing users to select seismic events belonging to consistent quality classes and giving a more controlled image of the Italian instrumental seismicity for tectonic and geodynamical studies. The resulting catalog gives a new, coherent view of the spatial and temporal distribution of Italian seismicity. By selecting well constrained located events we construct the new Italian Crustal Seismogenic Layer (CSL) with a good spatial resolution, allowing us to show a comparison between seismogenic thicknesses and Moho geometry distribution. We finally present some examples of seismicity distribution in selected areas of Italy at regional and local scale relating the relocated events of our catalog with available multidisciplinary information from geology, geochemistry, geodynamical models, and historical seismicity.