Annals of Geophysics
https://www.annalsofgeophysics.eu/index.php/annals
Annals of Geophysics is an international, peer-reviewed, diamond open-access, online journal. Annals of Geophysics welcomes contributions on primary research on Geophysics, Seismology, Volcanolgy Physics and Chemistry of the Earth, Physics of the High Atmosphere.Istituto Nazionale di Geofisica e Vulcanologia, INGVen-USAnnals of Geophysics1593-5213<h4>Open-Access License</h4> <p><strong><em>No Permission Required</em></strong></p> <p><a href="http://www.ingv.it" target="_blank" rel="noopener">Istituto Nazionale di Geofisica e Vulcanologia</a> applies the Creative Commons Attribution License (CCAL) to all works we publish.</p> <div style="text-align: center;"> <p><a href="http://creativecommons.org/licenses/by/3.0/" rel="license"><img style="border-width: 0;" src="http://i.creativecommons.org/l/by/3.0/88x31.png" alt="Creative Commons License" /></a></p> </div> <p>Under the CCAL, authors retain ownership of the copyright for their article, but authors allow anyone to download, reuse, reprint, modify, distribute, so long as the original authors and source are cited. No permission is required from the authors or the publishers.</p> <div>In most cases, appropriate attribution can be provided by simply citing the original article.</div> <div>If the item you plan to reuse is not part of a published article (e.g., a featured issue image), then please indicate the originator of the work, and the volume, issue, and date of the journal in which the item appeared. For any reuse or redistribution of a work, you must also make clear the license terms under which the work was published.</div> <div>This broad license was developed to facilitate open access to, and free use of, original works of all types. Applying this standard license to your own work will ensure your right to make your work freely and openly available. For queries about the license, please contact ann.geophys@ingv.it. <p> </p> </div>Spatial and Temporal Analysis of Carbon Dioxide Concentrations over Italy by means of OCO‑2 Satellite Data Series
https://www.annalsofgeophysics.eu/index.php/annals/article/view/9000
<p>Carbon dioxide is a greenhouse gas with sink and source related to natural cycles and anthropic activities. OCO‑2 is a NASA carbon dioxide dedicated mission launched in 2014 aimed to measure the CO2 concentrations in the atmosphere by recording sunlight reflected off the Earth and provides, at the state of the art, the highest spatial resolution for mapping CO2 at global scale. In this work, for the first time, we statistically analyse 8 years of OCO‑2 acquisitions over Italian territory, obtaining the main trend and the seasonal behaviour of CO2 over land. After data reprocessing and compensating on temporal frequency of OCO‑2 acquisitions over Italy, a mean of 21 ppm of increment in the period from 2015 to 2022 has been found. In the data time series, we also noticed a significant acceleration in the trend between 2019 and 2020 and a return to average values of the trend after the COVID19 pandemic lockdown. In addition, such trends have been compared with those achieved by the European Centre for Medium Range Weather Forecasts (ECMWF) model. The data time series was also used to perform a spatial analysis of areas characterized by lower/higherc CO2 concentrations to detect sinks/sources in Italy due to the land use. The analysis reveals that the North Italian regions, with more population and industries, are the source of CO2; moreover, the fundamental role of vegetation as a sink of CO2 is confirmed.</p>Vito RomanielloClaudia SpinettiAlessandro Piscini
Copyright (c) 2024 Vito Romaniello, Claudia Spinetti, Alessandro Piscini
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2024-02-292024-02-29665PA533PA53310.4401/ag-9000Ionospheric equivalent slab thickness ingestion into the NeQuick model
https://www.annalsofgeophysics.eu/index.php/annals/article/view/9026
<p>The ionospheric equivalent slab thickness (<em>τ</em>), defined as the ratio of the vertical total electron content (vTEC) to the ionospheric F2-layer electron density maximum (<em>Nm</em>F2), is a parameter providing useful information on the shape of the vertical electron density profile. However, the use of this information is of difficult practical application in empirical ionosphere models, such as the NeQuick model, because by design they do not explicitly include <em>τ </em>as a modelling parameter. In this work, we investigated the opportunity of using measured <em>τ </em>values to improve the empirical modelling of the ionosphere vertical electron density profile by NeQuick. Measured <em>τ </em>values were obtained through <em>Nm</em>F2 observations and vTEC measurements obtained between 2001 and 2019 by an ionosonde and a ground-based GNSS receiver, respectively, co-located at Rome ionospheric station (41.8° N, 12.5° E; Italy). NeQuick <em>τ </em>was obtained as the ratio between modelled <em>Nm</em>F2 and vTEC values, the latter obtained by integration of the vertical profile. As a first step, <em>τ </em>values modelled by NeQuick were compared with corresponding values measured at Rome station to highlight diurnal, seasonal, and solar activity differences. Then, measured <em>τ </em>values were ingested in NeQuick through a three-parameter assimilation procedure which first assimilate F2-layer peak characteristics to constrain the F2-layer anchor point, and then assimilate vTEC to optimize the F2-layer shape through the NeQuick F2-layer thickness parameter, namely <em>B</em><sub>2bot</sub>. The assimilation procedure provides information on how the NeQuick <em>B</em><sub>2bot</sub> has to be modified to match measured <em>τ</em> values, and then on how the shape of the F2-layer profile has to be changed accordingly. Our results highlight that, in many cases, the NeQuick <em>B</em><sub>2bot</sub> has to be increased to match observations, which has implications on the modelling of the NeQuick bottomside and topside effective scale heights.</p>Alessio PignalberiBruno NavaMarco PietrellaMichael PezzopanePierdavide CoïssonClaudio Cesaroni
Copyright (c) 2024 Alessio Pignalberi, Bruno Nava, Marco Pietrella, Michael Pezzopane, Pierdavide Coïsson, Claudio Cesaroni
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2024-02-262024-02-26665PA528PA52810.4401/ag-9026Improving seimic hazard assessment in the Mediterranean Region
https://www.annalsofgeophysics.eu/index.php/annals/article/view/8881
<p class="p1">This paper is intended as a short presentation of the main limitations affecting seismic hazard</p> <p class="p1">assessment, revisiting possible methods available in the literature to be applied for this purpose.</p> <p class="p1">The convergence of the African Plate with the Eurasian Plate is the cause of the high seismic activity characterizing the Mediterranean region, with particular intensity in its eastern part. It is clear that the associated seismic risk requires appropriate measures for its mitigation. Seismic risk, the amount of resources that the community is expected to pay to earthquakes in the long term, is the product of three factors, such as seismic hazard, vulnerability and value of the exposed goods. As earthquakes cannot be prevented, seismic risk can be mitigated by improving our knowledge of seismic hazard, which is largely based on statistical analysis of historical earthquake catalogs.</p> <p class="p1">Nevertheless, historical records are affected by problems of reliability, completeness and shortness, as they commonly span time lengths of the same order of magnitude or even shorter than the inter-event time of the strongest earthquakes produced by specific seismic sources. In this respect, alternative methods can be proposed for integrating and improving our knowledge of seismogenic processes, and estimating both time-independent and time-dependent occurrence rates of strong earthquakes. We propose the application of physics-based earthquake simulators, requiring the knowledge of a robust geological-geophysical seismogenic model.</p>Rodolfo ConsolePaola Vannoli
Copyright (c) 2023 Rodolfo Console, Paola Vannoli
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2024-02-262024-02-2666510.4401/ag-8881Large Earthquakes Recurrence Time in the Kefalonia Transform Fault Zone (KTFZ), Greece: Results from a physics-based simulator approach
https://www.annalsofgeophysics.eu/index.php/annals/article/view/8936
<p class="p1"><span class="s1">Large earthquakes mean recurrence time (T</span><span class="s2">r</span>) on specific fault segments is one of the primary input parameters for developing long-term Earthquake Rupture Forecast (ERF) models in a specific time span considering either a time-independent or an elastic rebound motivated renewal assumption.</p> <p class="p1">An attempt is made to define Tr on the major fault segments comprised in Kefalonia Transform Fault Zone (KTFZ), which is an active boundary demarcating from the west the area of central Ionian Islands, namely Lefkada and Kefalonia, and is associated with remarkably high seismic activity.</p> <p class="p2">Frequent large (M<span class="s2">w </span><span class="s3">≥ </span>6.0) earthquakes are reported to have caused severe damage during the last six centuries. Although the number of large earthquakes (including both historical and instrumental) is satisfactory enough for regional hazard studies, their number become very limited when they are subdivided into subsets assigned to specific fault segments. Physics-based earthquake simulators are approaches to overcome recurrence intervals shortage, due to their ability to generate long lasting earthquake catalogs. The application of a physics-based simulatorn the KTFZ, is attemped upon a detailed fault network model and implemented multiple times and with a wide range of input parameters, aiming at the definition of the most representative simulated catalog in respect to the observed regional seismicity. The most representative simulated catalog is finally used for investigating the recurrence behavior of large (M<span class="s2">w </span><span class="s3">≥ </span>6.0) earthquakes and assessing whether the renewal model performs better that the Poisson model, after considering both individual and multiple ruptured segments scenarios.</p>Christos KourouklasRodolfo ConsoleEleftheria PapadimitriouVassilios KarakostasMaura Murru
Copyright (c) 2023 Christos Kourouklas, Rodolfo Console, Eleftheria Papadimitriou, Vassilios Karakostas, Maura Murru
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2024-02-262024-02-2666510.4401/ag-8936Monitoring the vegetation stress coming from anthropogenic activities by modeling phenology using Sentinel-2 data
https://www.annalsofgeophysics.eu/index.php/annals/article/view/8837
<p class="p1">The study aimed at verifying the existence of stress induced on the functionality of natural ecosystems by particularly impacting anthropogenic activities. In detail, a methodology has been developed to evaluate any alterations in the phenology of plant species in areas surrounding sites defined by Italian legislation as “potentially polluted”. Specifically, the study areas located in Basilicata (southern Italy) were intended for municipal solid waste management activities and, at some stage of their management, Potential Toxic Elements (PTEs) concentrations were recorded above the thresholds permitted by the current legislation. The phenological trends of the vegetation were analyzed at gradually increasing distances from the centroid of the sites and then compared with points of the same type of vegetation, very distant from the sites, in areas that were not reasonably impacted by any contamination. The reconstruction of the phenological trends was carried out using Sentinel-2 images approximately on a monthly basis from which the Normalized Difference Vegetation Index (NDVI) was evaluated. Finally, the trends between areas adjacent the sites and unpolluted ones were statistically analyzed using dissimilarity indices which led to the conclusion of the non-existence of effects induced by PTEs on the functionality of the vegetation.</p>Giuseppe MancinoRodolfo ConsoleMichele GrecoMaria Lucia TrivignoAntonio Falciano
Copyright (c) 2023 Giuseppe Mancino, Rodolfo Console, Michele Greco, Maria Lucia Trivigno, Antonio Falciano
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2024-02-262024-02-2666510.4401/ag-8837Random Forest based estimate to assess the damages of future earthquakes: preliminary results
https://www.annalsofgeophysics.eu/index.php/annals/article/view/8935
<p>In this paper we present a case study where the Random Forest (RF) Classifier, has been used to estimate the damage to buildings caused by a (possible) future earthquake, starting from the data of past earthquakes. This prelaminar work is based on the Shakedado dataset, which contains information on buildings and ground shaking parameters for the six major earthquakes that occurred in Italy between 1981 and 2012. We perform the following two conceptual experiments</p> <ul> <li><em>E1: Assume that the sequence that hit Emilia has just ended and the data relating to the other major earthquakes happened in the past (L’Aquila, Pollino, and Irpinia) are available, then calculate the level of damage for each building in the Emila dataset.</em></li> <li><em>E2: Assume that the sequence that hit Pollino has just ended and the data relating to the other major earthquakes happened in the past (L’Aquila, Emilia) are available, then calculate the level of damage for each building in the Pollino dataset.</em></li> </ul> <p>Both training and test datasets contain only masonry buildings located within 10 km of the main shock of each sequence. The results show the RF algorithm’s ability to discriminate between buildings with light/no damage from those with medium/severe damage, with a good accuracy, especially for E1.</p>Federica Di MicheleEnrico StagniniDonato PeraRoberto Aloisio Pierangelo Marcati
Copyright (c) 2024 Federica Di Michele, Enrico Stagnini, Donato Pera, Roberto Aloisio , Pierangelo Marcati
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2024-02-262024-02-2666510.4401/ag-8935Pedogenic effect and the impact of erosion factors on topsoil magnetic susceptibility enhancement
https://www.annalsofgeophysics.eu/index.php/annals/article/view/8896
<p>The main aims of this study were to i) investigate the impact of erosion factors including land use, slope position, and lithology on magnetic susceptibility (MS) of soil, and ii) detecting the pedogenic effect on MS enhancement using simple methods, including median absolute deviation (MAD), topsoil-subsoil difference methods, MS magnitude and Dearing’s model. Soil cores were sampled along five slope positions in two transects selected in forested and cultivated lands in a watershed located in north of Morocco. The results showed higher values of MS in the upperslopes in forested land due to soil stability, and lower ones in middleslopes and lowerslopes due to soil erosion. However, MS is higher in cultivated land in middleslopes due to soil deposition and it is lower in the upperslopes due to erosion. The results confirmed the pedogenic effect on MS. This is confirmed by i) enhanced Forster factor and low values of magnetic susceptibility background, ii) dominance of ultrafine super-paramagnetic/stable single-domain ferrimagnetic grains in almost all studied soils, and iii) absence of anomaly in MAD data set and pertinence of the results of MAD and topsoil-subsoil difference methods.</p>Naima BouhsaneSaidati Bouhlassa
Copyright (c) 2023 Naima Bouhsane, Saidati Bouhlassa
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2024-02-262024-02-26665GM527GM52710.4401/ag-8896The March 2023 UAS-based high-resolution Digital Surface Model and orthomosaic of the NE flank of Stromboli volcano (Sicily, Italy)
https://www.annalsofgeophysics.eu/index.php/annals/article/view/8982
<p class="p1">Stromboli is a volcanic island in a persistent state of activity, located in the Tyrrhenian Sea off the northern coast of Sicily. During the night of 25 and 26 May 2022, a massive human-caused wildfire destroyed most of the vegetation cover on the NE flank of the island, just above the main village.</p> <p class="p1">On 12 August 2022, a particularly heavy rainfall event remobilized the loose volcaniclastic deposits that covered the burned volcanic flank, no longer protected by the vegetation. This event triggered several debris flows that were channeled by the roads and flooded several streets and buildings, causing severe damage to the village. In late-March 2023, just before the large spring vegetation growth, we conducted an Unmanned Aerial System (UAS) photogrammetric campaign over a sector of the NE flank of Stromboli Island, to acquire data on an area massively affected by the wildfire first and by the debris flows later. Here we present and share with the scientific community and civil authorities the results of this UAS campaign, which consists of a 1.4 km<span class="s1">2 </span>wide 10 cm-resolution Digital Surface Model (DSM) and 1.6 cm-resolution orthomosaic. These data clearly show the dramatic consequences of the 2022 tragic events at Stromboli. We also produced an elevation difference map by comparing the 2023 DSM here generated and the 2012 LiDAR DEM to provide a first overview of the thickness of the deposits that were removed from the Stromboli NE flank.</p>Luca NannipieriAndrea BevilacquaFederico Di TragliaMassimiliano FavalliAlessandro Fornaciai
Copyright (c) 2023 Luca Nannipieri, Andrea Bevilacqua, Federico Di Traglia, Massimiliano Favalli, Alessandro Fornaciai
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2024-02-262024-02-26665DM526DM52610.4401/ag-8982Comparative Analysis of Methods to Estimate Geodetic Strain Rates from GNSS Data in Italy
https://www.annalsofgeophysics.eu/index.php/annals/article/view/9015
<p>Our ability to estimate surface deformation rates in the Central Mediterranean has considerably enhanced in the last decade thanks to the growth of continuous Global Navigation Satellite System (GNSS) networks. Focusing on the Apennine/Alpine seismogenic belt, this area offers the opportunity to test the use of geodetic strain rates for constraining active tectonic processes and for seismic hazard assessments. Given the importance of geodetic strain rate models in modern hazard estimation approaches, however, one has to consider that different approaches can provide significantly different strain rate maps. Despite the increasing availability of GNSS velocity data, in fact, strain rate models can significantly differ, because of the spatial heterogeneity of GNSS stations locations and inherent strategies in computing strain rates. Using a dense GNSS velocity dataset, this study examines three methods for estimating horizontal strain rates, described in the recent literature and selected to represent approaches of increasing mathematical complexity. Advantages, drawbacks and optimal settings of each method are discussed. The main result is an ensemble of strain rate models that enable the evaluation of epistemic uncertainties in seismicity rates models constrained by geodetic velocities.</p>Riccardo NucciEnrico SerpelloniLicia FaenzaAlexander GarciaMaria Elina Belardinelli
Copyright (c) 2024 Riccardo Nucci, Enrico Serpelloni, Licia Faenza, Alexander Garcia, Maria Elina Belardinelli
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2024-02-262024-02-26665DM531DM53110.4401/ag-9015Sediment-thickness and upper-lower crustal boundary of the Maracaibo block, Venezuela, from gravity study
https://www.annalsofgeophysics.eu/index.php/annals/article/view/8981
<div class="page" title="Page 1"> <div class="layoutArea"> <div class="column"> <p>The Maracaibo Block is a triangularly shaped fraction of independent continental lithosphere located in north‐western Venezuela, controlled by a complex system of strike‐slip and thrusts faults; the Oca‐Ancon fault (north), the Santa Marta‐Bucaramanga fault (southwest) and Boconó fault (east). In the present research we study two interfaces associated with the upper crust, the basement‐sediment, and the upper‐lower crustal interface, as well the interaction with the Caribbean plate. These interfaces were defined using gravimetric inversion methods in conjunction with well information, refraction and reflection seismic and seismological data. Applying the inversion algorithm of Cordell and Henderson to the gravimetric data, 10 km of sedimentary column are estimated in the deepest part of the Maracaibo Lake basin and 5 km in the Apure Barinas basin, both zones coincide with the minimum gravimetric anomaly of each basin. Using spectral analysis, a discontinuity with depths between 17 and 24 km is observed; located between the upper and lower crustal boundary. Four gravimetric domains are defined; to the north related to the displacement of the Oca‐Ancon fault and its influence on the Bonaire block, to the west the displacement of the Santa Marta Bucaramanga fault, to the east the Apure fault and the central domain, relacionated with the Maracaibo block. There are 60 km of distance between the gravity minimums belonging to the Apure Barinas and Maracaibo Lake basins; this displacement is associated with the right lateral strike slip offsets of the Boconó fault. The displacement of Boconó fault, and the shortening in a northeast‐southeast direction, is consistent with ongoing strain partitioning in the Mérida Andes. A displacement of 110 km is proposed for the Santa Marta Bucaramanga fault and 100 km for the Oca Ancon fault, respectively. The first pulses of Oligocene uplift of the Merida Andes are due to the interaction of the Maracaibo block with the Caribbean plate. The uplift of the Merida Andes was dominated mainly by the northwest‐southeast compression until 4 Ma ago; in the Pleistocene, the displacement of the Boconó fault and the rotation of the Trujillo block began to control the current structural configuration of the northeastern Mérida Andes. This interaction gives rise to a pattern of gravimetric lows and highs associated with subbasins and basement highs, located between Oca Ancón and Boconó faults.</p> </div> </div> </div>Francisco AraujoNuris Orihuela
Copyright (c) 2024 Francisco Araujo, Nuris Orihuela
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2024-02-262024-02-26665DM532DM53210.4401/ag-8981Atmospheric Correction of FG5 Absolute Gravimetry Data using Measured Air Pressure
https://www.annalsofgeophysics.eu/index.php/annals/article/view/8993
<p>Changes in atmospheric density affect atmospheric pressure, which is a key factor affecting highprecision gravity measurement. Currently, atmospheric correction of absolute gravity measurements uses the empirical admittance value recommended by the International Association of Geodesy (−0.3 μGal/mbar); however, the actual admittance value changes with atmospheric mass and time. In this study, we determine the effect of using measured admittance values for absolute gravity correction. First, high-precision relative gravimeters (GWR OSG-057, Scintrex CG5) are used for continuous gravity measurements. Then, air pressure measured by the pressure sensor equipped by FG5 absolute gravimeter is used to obtain the atmospheric admittance using the iterative least squares method, which is compared with the theoretical atmospheric admittance. Taking FG5-257 as an example, we use the measured admittance for atmospheric correction of absolute gravity at four different elevations (Lhasa, Nagqu, Gar, and Suining, China). The results are as follows: 1) According to co-location measurements in Lhasa, CG5 and OSG gravimeter measured admittance values exhibit comparable precision (–0.332± 0.003 μGal/mbar and –0.332± 0.001 μGal/mbar,respectively),though the CG5 has larger standard deviation. 2) After correction using the measured admittance, changes in set standard deviation and measurement precision are approximately 0.01 μGal; however, the effect on the measurement results does not exceed 1 μGal, which is equivalent to the measurement precision of FG5. Therefore, measured admittance values are only recommended for atmospheric correction of high-precision absolute gravity measurements.</p>Dulin ZhaiZiwei LiuLei BaiHao ZhouJianing Gou
Copyright (c) 2024 Dulin Zhai, Ziwei Liu, Lei Bai, Hao Zhou, Jianing Gou
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2024-02-262024-02-26665GD530GD53010.4401/ag-8993Point clouds repeatability and fast scale factor estimates in free SfM surveying: terrestrial application and empirical approach
https://www.annalsofgeophysics.eu/index.php/annals/article/view/9009
<p class="p1">Previous experiments highlighted the possible existence of a relation between repeatability of point clouds obtained from Structure-from-Motion photogrammetry (SfM), represented by the standard deviation (𝜎), and the nominal ground sampling distance (GSD). In particular, the empirical relation 3𝜎 ∼ 2.5 <span class="s1">GSD </span>was found. For this reason, in-situ tests aimed at studying this relation were carried out. Data from seven surveys carried out in 2018-2022 time span allowed the comparison between 20 pairs of almost contemporary point clouds, generated by means of relative bundle adjustment (BA) without ground control points (GCPs) and then relatively scaled and aligned. In this way, the relation 3𝜎 = <span class="s1">aGSD </span>was found, where <span class="s1">a </span>= 2.5 <span class="s1">± </span>0.4. This result also suggested the use of the reverse procedure, where the scale factor (<span class="s1">SF</span>) is estimated from the standard deviation of non-metric point <span class="s1">clouds, </span>𝜎<span class="s2">nmu</span>, by using the relation <span class="s1">SF</span><span class="s2">a </span>= <span class="s1">aGSD/</span>3𝜎<span class="s2">nmu</span>. Additional checks proved that <span class="s1">SF</span><span class="s2">a </span>differs from <span class="s1">SF </span>by 3%. This error is not acceptable error for length, area or volume measurements, but the estimated <span class="s1">SF</span><span class="s2">a </span>is more than adequate for a fast, rough registration of photogrammetric models aimed at searching patterns or precursors of incipient phenomena in impervious/inaccessible areas or in emergency conditions.</p>Arianna PesciGiordano TezaFabiana Loddo
Copyright (c) 2024 Arianna Pesci, Giordano Teza, Fabiana Loddo
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2024-02-262024-02-26665RS529RS52910.4401/ag-9009