Annals of Geophysics (INGV, Istituto Nazionale di Geofisica e Vulcanologia)
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3‑D inversion and accuracy assessment of gravitational data to determine the depth of sedimentary layers; An Application in the Burg El‑Arab Area, Northwestern Desert of Egypt
Full text linkThe study aims to determine the depth of subsurface sedimentary layers using a Fourier‑based 3‑D stripping inversion method and assess its accuracy. The seismic‑based depth maps of the topDabaa, Kharita, and El Alamein Formations in the Burg El‑Arab Area were utilized to evaluate the inversion process’s accuracy. The calculated gravity effects of the top Dabaa, Kharita, and El Alamein Formations range were analytically estimated from thickness and density contrast and assigned to the surface observation level (Bouguer stations) before sequential stripping. The apparent density was calculated in addition to the upper and lower depth bounds of each sedimentary layer, which were used as constraints during 3‑D Fourier‑domain inversion procedure. The inversion results showed satisfactory fit statistics compared to seismic‑based depth data. The analysis of the inversion’s performance for the three inverted sedimentary layers showed that the percentage error between the inverted‑based depth and the seismic‑based depth was ranging from ±0.004 to 21.67%. The seismic and inverted‑based depths of the top Dabaa, Kharita, and El Alamein Formations were found to have correlation coefficient values of 0.88, 0.82, and 0.75, respectively. A 2‑D model was created for four horizons, including the basement layer. The 2‑D modeling indicated that the study area is affected by a number of normal faults that cross most of the layers and dip into the NE and SW directions, with dipping angles ranging from 70° to 80° and 75° to 85°, respectively. The 3‑D inversion results demonstrated that gravity measurements can accurately determine the depth of the sedimentary layer when stripping is performed at the Bouguer‑station level and the inversion is constrained by density and seismic information, with a tolerance of up to 21.67% and decrease until it matches the true depth in some locations
Application of the Vertical‑to‑Horizontal (VH) Ratio of the Peak Ground Velocity (PGV) in the Bay of Algiers using Data from Weak to Moderate Earthquakes
Full text linkThis research aims to identify the most appropriate predictor for the Vertical‑to‑Horizontal (VH) ratio of the Peak Ground Velocity (PGV) from the five existing models in the literature useful for regional or site‑specific probabilistic seismic hazard assessment, and practical applications in the Bay of Algiers. Firstly, dataset of 285 observed VH ratios of PGV was compiled from nine seismic stations within the study area, installed on different flat and irregular surfaces. This dataset was derived from earthquakes with moment magnitude (Mw) ranging from 3.3 to 5.3. Next, the dataset was categorized into two groups based on the soil type at the station locations: rock (S1) (Vs30 above 800 m/s) and stiff (S2) (Vs30 360‑800 m/s) soils. After that, a preliminary linear regression analysis was performed for each group of observed VH ratios of PGV as a function of the Joyner‑Boore distance (RJB) of near field and compared with three selected candidature predictors: Akkar et al. (2014), Bozorgnia and Campbell (2016), and Ramadan et al. (2021) (RA2021). For an extensive evaluation, the Euclidean Distance‑based ranking method (EDR) was applied on the three mentioned candidature predictors. For rocky soil, the results indicate that all models closely align with the linear regression fit, around a VH ratio of PGV of 0.6. However, RA2021 appears to provide a reasonable fit, with a VH ratio of PGV of 0.4 for stiff soil, despite the significant site‑effects at the respective stations. The EDR showed that RA2021 gives the lowest sigma with the observed ratios for S1 and S2 soil classes. For the far field, estimates of the VH ratio of PGV are provided for three strong earthquake magnitudes (6.5, 7.0, and 7.5) and different soil classes, using the existing models
Seismic event location with a small aperture DASarray: a case‑study from DIVE ICDP drilling project
Full text linkDistributed Acoustic Sensing (DAS) has emerged as an innovative technology in seismology, sensing seismic waves along fiber optic cables and, thus, increasing ten‑folds the spatial density of seismic measurements. However DAS potential in seismic monitoring is still under investigation. In this study, we assess the differences in seismic event detection and localization when using DAS, conventional seismometers, and combination of both, by analyzing a dataset acquired during a field experiment in Megolo di Mezzo (Northern Italy). A ~1 km buried fiber optic cable was deployed with an almost L‑shape configuration. Seismic data were continuously recorded from November 2023 to February 2024 and compared with simultaneous observations from the local seismic network (DIVEnet). Several local earthquakes were detected, including microseismic events not listed in the official catalog. P‑wave arrival times were extracted from DAS recordings using different picking algorithms and compared to manual picks from seismometers. Event localization was performed through a Bayesian Monte Carlo approach applied separately to DAS and seismometer data, and jointly. Results demonstrate that DAS shows considerable potential in earthquake detection, particularly for low‑magnitude events and those occurring close to the fiber optic cable, as potentially expected during anthropic activities underground. The joint inversion of DAS and seismometer datasets reduced localization uncertainties and produced solutions consistent with the official INGV catalog. However, differences of up to ~2 km between DAS – and seismometer – based epicenters highlight the limitations of simplified velocity models and the impact of network geometry. These findings confirm the complementarity of DAS and traditional networks and underline the potential of hybrid monitoring strategies for advancing earthquake detection and characterization in complex geological environments
Tectonic evolution of the Central Anatolian Crystalline Complex: Insights from using magnetic and gravity data
No full textThis study investigates the inherited crustal architecture and concealed tectonic boundaries of the Kırşehir Massif, a key component of the Central Anatolian Crystalline Complex (CACC), using satellite‑derived potential field datasets. Earth Magnetic Anomaly Grid 2 (EMAG2) magnetic anomalies and World Gravity Map 2012 (WGM2012) Bouguer gravity data were analyzed together with multiple edge‑detection filters, including Total Horizontal Gradient (THG), Tilt Angle (TA), Theta Map (TM), and Tilt Angle of Horizontal Derivative Amplitude (TAHG), to enhance structural boundaries andidentify subsurface discontinuities prior to geological interpretation. The enhanced magnetic and gravity fields reveal two principal lineament sets trending NW‑SE and NE‑SW, which coincide with major lithological contacts, fault zones, and the boundaries of the İzmir‑Ankara‑Erzincan Suture Zone (IAESZ) and Inner Tauride Suture Zone (ITSZ). Quantitative lineament classification based on azimuth and length statistics further confirms three dominant structural orientations (NW‑SE, NE‑SW, and E‑W), reflecting both inherited suture‑related structures and younger transtensional deformation. By integrating filtered anomaly gradients with regional geological constraints, this study provides the most detailed potential‑field‑based structural model of the Kırşehir Block to date and offers new insights into crustal inheritance, lithospheric segmentation, and the multi‑phase tectonic evolution of Central Anatolia
Historical Perspective and Critical Reviewof the Seismic Swarm Concept
No full textEarthquake swarms are clusters of seismic events occurring in a localized area over a short time span, without a dominant mainshock. Unlike typical mainshock‑aftershock sequences, seismic swarms feature earthquakes of similar magnitude and unpredictable temporal patterns. Their occurrence can be put in relation with crustal heterogeneity, fluid migration, and volcanic activity, including related geothermal processes. The concept of earthquake swarm emerged in the late19th century, with the early key contribution from Josef Knett in Europe. In Japan, renewed interest in the mid‑20th century – especially following the development of modern recording techniques and the Matsushiro swarm (1965‑1967) – led to major advancements made by researchers like Kiyoo Mogi and Takeo Utsu, who contributed two complementary approaches to swarm classification:quantitative and statistical, respectively. Parallel developments occurred in the United States and Europe, gradually shaping earthquake swarms as a distinct seismological phenomenon. By providing a historical perspective on the concept of seismic swarms, this work establishes a context for our future research, which will focus on the application of statistical models, such as the Epidemic Type Aftershock Sequence (ETAS) model
Two Thousand Years of Historical‑Archaeological Observations of Bradyseism in Pozzuoli
No full textThe Serapeum of Pozzuoli has long served as a pivotal site for scholars seeking to integrate geology, archaeology, and historical records to study the phenomenon of ground deformation in the CampiFlegrei area. Early modern observations of slow vertical ground movements in Pozzuoli laid the groundwork for understanding a process that has persisted for millennia, leaving tangible traces in stone, inscriptions, and ancient manuscripts. The interplay between human activity and the dynamic volcanic environment is revealed through architectural remains, epigraphic evidence, and historical accounts, highlighting both the resilience and vulnerability of urban settlements to bradyseism events. This study synthesizes archaeological, historical, and geological data to reconstruct the evolution of ground deformation in Pozzuoli, emphasizing the Serapeum as a unique reference point for interdisciplinary research and for evaluating long‑term hazards in volcanic regions
Acknowledgement to Reviewers 2025
No full textThe strength and credibility of a scientific journal rest upon the rigor, fairness, and dedication of its peer-review process. At Annals of Geophysics, peer review is not merely a procedural step; it is the foundation upon which the quality and integrity of our published research are built. On behalf of the Editorial Board of Annals of Geophysics, I wish to express our deepest gratitude to all the reviewers who, throughout the year, have generously devoted their time, expertise, and thoughtful judgment to the evaluation of submitted manuscripts. Their careful assessments, constructive recommendations, and commitment to high scientific standards ensure that the research we publish is original, methodologically sound, and relevant to the broader geoscientific community. As a Diamond Open Access journal, Annals of Geophysics is committed to making high-quality scientific research freely accessible to the global community without financial barriers for authors or readers. In this model, the contribution of reviewers becomes even more essential, as the strength and sustainability of the journal rely fundamentally on academic service, shared responsibility, and scholarly integrity. Thanks in no small part to their dedication, Annals of Geophysics has continued to strengthen its scientific standing. In 2025, the journal recorded an improvement in its Impact Factor, a result that reflects both the quality of the contributions we receive and the rigor of the evaluation process that shapes them. This achievement is the outcome of a collective effort involving authors, reviewers, and the Editorial Board working together to uphold the highest standards of scientific publishing. Peer review remains one of the most essential expressions of academic responsibility and collegiality. The continued growth, credibility, and international visibility of the journal depend directly on this shared commitment to excellence. For this reason, the Editorial Board is particularly pleased to recognize the Top 10 Outstanding Reviewers of 2025. Selected on the basis of the number of completed reviews, timeliness, and the depth and constructiveness of their reports between January 1 and December 31, 2025, these colleagues have made an exceptional contribution to improving the quality of manuscripts and strengthening the journal as a whole. To all our reviewers, we extend our sincere appreciation. We look forward to continuing this collaborative work in advancing the quality, integrity, and impact of Annals of Geophysics in the years ahead
New geophysical and archaeological investigations at the Nunziatella site in Mascali, Mount Etna (Italy)
No full textEtna volcano is characterized by a rich presence of archaeological sites documenting uninterrupted human activity along its lower flanks since the Greek colonization (734/735 B.C.) in Sicily. Within this context is the Nunziatella site in Mascali territory, located on the lower eastern flank of Etna, an area favoured for human settlement by the presence of water sources. The Nunziatella site is known for housing the medieval church of Maria Santissima Annunziata (12th century A.D.) and a small Paleo‑Christian basilica (5th‑6th century A.D.), but clues suggested the presence of additional buried structures. To better investigate the Nunziatella site, an interdisciplinary study was conducted, combining non‑invasive geophysical surveys (GPR), archaeological excavations and C14 dating. GPR results revealed an elongated anomaly with a defined geometry south of the church, hypothesizing buried structures at 0.5‑2 meters depth. The geophysical surveys proved to be a fundamental tool for guiding the excavations. The archaeological excavations confirmed the existence of a building, bringing to light a wall over nine meters‑long parallel to the church’s south facade, featuring interior plaster and a cocciopesto floor at the base that is characterized by the presence of two pits. These latter have revealed numerous fragments of ceramics, tiles and pottery of Byzantine era confirmed by the C14 age of a bone fragment (663‑775 A.D.). The pits refer to a phase of abandonment of the building whose construction took place in an era certainly prior to the 8th/9th century A.D. This new data allows us to hypothesize the presence in this area of a large Late Roman‑Byzantine monumental complex of unknown function confirming the historical importance of the Nunziatella site since ancient time
Magnetic Inversion under Remanent Conditions Using Equivalent Layer Direction Estimation and VOXI Earth Modelling
Full text linkRemanent magnetisation is a critical challenge in magnetic interpretation, often leading to mispositioned anomalies and unreliable inversion results when neglected. This study applies and validates a practical, sequential two‑step workflow that integrates existing techniques to improve magnetic modelling in scenarios where remanent components significantly influence the anomaly geometry. In the first stage, the total magnetisation direction is estimated using the Equivalent Layer technique, which reconstructs the effective magnetisation vector from the observed anomaly without decomposing it into induced and remanent components. The magnetisation direction estimated via the equivalent layer technique was used to perform the reduction to the pole (RTP), and the inversion was subsequently carried out assuming a vertical inducing field (D = 0°, I = 90°). The methodology was tested on synthetic models with varying remanent contributions to evaluate its performance in controlled conditions. Results demonstrate that incorrect directional assumptions lead to distorted source geometries and underestimated susceptibilities, whereas using the Equivalent Layer estimated direction significantly improves inversion accuracy. The approach was also applied to a real airborne magnetic dataset from Espírito Santo State, Brazil, where it successfully recovered a westward‑dipping magnetic body with coherent susceptibility structure. Residual analysis confirmed strong agreement between predicted and observed fields, reinforcing the method’s robustness. While the current implementation assumes a constant magnetisation direction within the target volume, making it less suitable for geologically complex bodies, it offers a stable and interpretable solution for cases where remanence is spatially coherent. This study provides a practical, reproducible workflow for the integrated application of EL‑based direction estimation, RTP, and VOXI susceptibility inversion to remanence‑affected datasets. This workflow is compatible with standard modelling platforms and provides a practical reference for remanence‑affected magnetic interpretation
Revisiting the 1968 Belice valley (western Sicily) earthquake sequence
No full textWe revisit the earthquake sequence that struck the Belice valley (western Sicily) in January‑February 1968. The sequence is characterized by several moderate earthquakes which occurred in close proximity in time and space, with the largest event recorded in the early hours of the 15th of January. To date we gathered the most comprehensive parametric data set of arrival times and surface wave magnitude (MS) readings in order to facilitate relocations and MS reassessments, respectively. The relocation results put the events in the middle-lower crust, with the hypocentres tightened compared to previous results. Our revised MS estimations for ten of the largest events of the sequence support a near-6 magnitude for the mainshock. We show that our MS results are in line with the information provided by the instrumental parametric data available, not just for the mainshock but also within the broader context of the entire sequence. Different from recent estimations, our results support a magnitude above 5.5 for the mainshock, but, at the same time, suggest that the mainshock magnitude value of 6.4 reported in various catalogues is overestimated