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Editorial for Special Issue “Precise GNSS Positioning and Navigation: Methods, Challenges, and Applications”
No full textThe Global Navigation Satellite System (GNSS) can provide users with high-precision positioning information continuously and benefits all walks of life, e.g., unmanned driving, urban navigation, deformation monitoring, etc. The important scientific research and application value of GNSSs have prompted many countries and regions to develop GNSS technologies. GNSS core positioning technologies, such as Precise Point Positioning (PPP) and Real-Time Kinematic positioning (RTK), can provide decimeter-level or even centimeter-level positioning accuracy in open environments. However, active GNSS positioning technologies are susceptible to complex conditions, including canyon environments, low-cost receivers, and multi-GNSS situations, and, on occasion, cannot provide accurate, continuous, and reliable positioning information. The diversification of GNSS systems and constellations, receiver types, and observation environments puts forward higher requirements for technology and algorithms to maintain high-precision positioning and navigation services. Advanced algorithms are key to solving GNSS practical application problems and expanding the scope of GNSS applications.
This Special Issue aims at studies covering improved methods and the latest challenges in precise GNSS positioning and navigation, especially under complex conditions for various research investigations as well as a range of practical applications. Both theoretical and applied research contributions to the GNSS high-precision technology in all disciplines are considered. Topics may cover anything from precise muti-GNSS positioning algorithms and GNSS data processing to more comprehensive targets and scales. Therefore, new algorithms for high-precision positioning and navigation, GNSS receivers, software development for data collection and processing, and their applications in various fields are all included.Published2271OST2 Deformazione e Hazard sismico e da maremotoJCR Journa
The 2022 Seismic Sequence in the Northern Adriatic Sea and Its Long-Term Simulation
No full textWe studied the long-term features of earthquakes caused by a fault system in the northern
Adriatic sea that experienced a series of quakes beginning with two main shocks of magnitude
5.5 and 5.2 on 9 November 2022 at 06:07 and 06:08 UTC, respectively. This offshore fault system,
identified through seismic reflection profiles, has a low slip rate of 0.2–0.5 mm/yr. As the historical
record spanning a millennium does not extend beyond the inter-event time for the largest expected
earthquakes (M ' 6.5), we used an earthquake simulator to generate a 100,000-year catalogue with
121 events of Mw 5.5. The simulation results showed a recurrence time (Tr) increasing from 800 yrs
to 1700 yrs as the magnitude threshold increased from 5.5 to 6.5. However, the standard deviation
s of inter-event times remained at a stable value of 700 yrs regardless of the magnitude threshold.
This means that the coefficient of variation (Cv = s/Tr) decreased from 0.9 to 0.4 as the threshold
magnitude increased from 5.5 to 6.5, making earthquakes more predictable over time for larger
magnitudes. Our study supports the use of a renewal model for seismic hazard assessment in regions
of moderate seismicity, especially when historical catalogues are not available.Published37462T. Deformazione crostale attiva4T. Sismicità dell'Italia6T. Studi di pericolosità sismica e da maremotoJCR Journa
The Community Stress-Drop Validation Study—Part I: Source, Propagation, and Site Decomposition of Fourier Spectra
No full textIn part 1, we run multiple GIT decomposition for different choices of model assumptions, namely three different window duration for Fourier calculation, two different parametrization of the attenuation, two different site constraints. We also considered different source models (Brune, Boatwright, Brune with kappa_source) and different approaches to estimate uncertainties of source parameters (i.e., considering the covariance matrix, Monte Carlo sampling of the residual distribution, model selection with threshold based on F-test).As part of the community stress-drop validation study initiative, we apply a spectral
decomposition approach to isolate the source spectra of 556 events occurred during
the 2019 Ridgecrest sequence (Southern California). We perform multiple decompositions by introducing alternative choices for some processing and model assumptions,
namely: three different S-wave window durations (i.e., 5 s, 20 s, and variable between 5
and 20 s); two attenuation models that account differently for depth dependencies; and
two different site amplification constraints applied to restore uniqueness of the solution. Seismic moment and corner frequency are estimated for the Brune and Boatwright
source models, and an extensive archive including source spectra, site amplifications,
attenuation models, and tables with source parameters is disseminated as the main
product of the present study. We also compare different approaches to measure the
precision of the parameters expressed in terms of 95% confidence intervals (CIs).
The CIs estimated from the asymptotic standard errors and from Monte Carlo resampling of the residual distribution show an almost one-to-one correspondence; the
approach based on model selection by setting a threshold for misfit chosen with an
F-ratio test is conservative compared to the approach based on the asymptotic standard
errors. The uncertainty analysis is completed in the companion article in which the outcomes from this work are used to compare epistemic uncertainty with precision of the
source parameters.Published1980–19913T. Fisica dei terremoti e Sorgente SismicaJCR Journa
MISARA: Matlab Interface for Seismo-Acoustic aRray Analysis
No full textVolcanic activity produces a broad spectrum of seismic and acoustic signals whose characteristics provide important clues on the underlying magmatic processes. Networks and arrays of seismic and acoustic sensors are the backbone of most modern volcano monitoring programs. Investigation of the signals gathered by these instruments requires efficient workflows and specialist software. The high sampling rates, typically 50 Hz or greater, at which seismic and acoustic waveforms are recorded by multistation networks and dense arrays leads to the rapid accumulation of large volumes of data, making the implementation of efficient data analysis workflows for volcano surveillance a challenging task. Here, we present an open‐source MATLAB graphical user interface, MISARA (Matlab Interface for Seismo‐Acoustic aRray Analysis), designed to provide a user‐friendly workflow for the analysis of seismoacoustic data in volcanic environments. MISARA includes efficient algorithm implementations of well‐established techniques for seismic and acoustic data analysis. It is designed to support visualization, characterization, detection, and location of volcano seismoacoustic signals. Its intuitive, modular, structure facilitates rapid, semiautomated, inspection of data and results, thus reducing user effort. MISARA was tested using seismoacoustic data recorded at Etna Volcano (Italy) in 2010, 2011, and 2019, and is intended for use in education and research, and to support routine data analysis at volcano observatories.Published1689–1702OSV4: Preparazione alle crisi vulcanicheJCR Journa
Qβ, Qc, Qi, Qs of the Gargano Promontory (Southern Italy)
No full textWe have provided the first estimate of scat-
tering and intrinsic attenuation for the Gargano Prom-
ontory (Southern Italy) analyzing 190 local earthquakes
with M L ranging from 1.0 to 2.8. To separate the intrin-
sic Q i and scattering Q s quality factors with the Wen-
nerberg approach (1993), we have measured the direct
S waves and coda quality factors ( Q , Q c ) in the same
volume of crust. Q parameter is derived with the
coda normalization method (Aki 1980) and Q c factor
is derived with the coda envelope decay method (Sato
1977). We selected the coda envelope by performing an
automatic picking procedure from T start = 1.5T S up to
30 s after origin time (lapse time T L ). All the obtained
quality factors clearly increase with frequency. The Q c values correspond to those recently obtained for the
area. The estimated Q i are comparable to the Q c at all
frequencies and range between 100 and 1000. The Q s
parameter shows higher values than Q i , except for 8 Hz,
where the two estimates are closer. This implies a pre-
dominance of intrinsic attenuation over the scattering
attenuation. Furthermore, the similarity between Q i and
Q c allows us to interpret the high Q c anomaly previ-
ously found in the northern Gargano Promontory up to
a depth of 24 km, as a volume of crust characterized by
very low seismic dumping produced by conversion of
seismic energy into heat. Moreover, most of the earth-
quake foci fall in high Q i areas, indicating lower level of
anelastic dumping and a brittle behavior of rocks.Published827-846OST1 Alla ricerca dei Motori GeodinamiciJCR Journa
A scoping review of seismic risk communication in Europe
No full textAlthough earthquakes are a threat in many countries and considerable resources have been invested in safety regulations, communities at risk often lack awareness and preparedness. Risk communication is a key tool for building resilient communities, raising awareness, and increasing preparedness. Over the past 2 decades, seismic risk communication has evolved significantly. This has led to a reorientation from a predominantly “one-way”, top-down communication model to the promotion of new models in which people, their needs, and their participation in disaster risk management are central elements. The 2015–2030 Sendai Framework recommendations, recent disaster experiences and research have highlighted that new models can improve communication effectiveness. In this paper, we critically explore this transition by conducting a scoping review (n=109 publications) of seismic risk communication in Europe. We analyse the approaches, messages, tools, and channels used for seismic risk communication and how they have changed over time. The results reveal that the stated goals of seismic risk communication are, in decreasing order, to share information, raise awareness, change behaviours/beliefs, and increase preparedness. Pupils, students, and citizens are the primary recipients of communication activities. Over the years, two trends have emerged. First, “two-way”, transdisciplinary and bottom-up communication models prevailed over the “one-way” model. Second, communication aimed more at promoting proactive behaviours than just informing the public. Face-to-face, hands-on activities, and serious games are key tools to engage with the public. The results also reveal the emerging role of social media to target different audiences/social groups. Strikingly, only one-fifth of the analysed publications explicitly build on or tests risk communication theories. Future research could focus on comparing practices across countries and risks (e.g., earthquakes and floods) and on innovating communication theories and methodologies, especially by incorporating the role of information technologies and social media.Published1155576OST2 Deformazione e Hazard sismico e da maremotoJCR Journa
Moment magnitude for earthquakes in the Etna volcano area
No full textAccurate quantification of seismic activity in volcanic regions is an important asset for im- proving hazard and risk assessment. This is especially true for densely populated areas, as in the case of Etna volcano (Southern Italy). There, the volcanic hazard is amplified by the seismic risk of acti ve faults, especiall y on the eastern flank of the volcano. In such a context, it is common to rely on moment magnitude ( M W ) to characterize seismicity and monitor the energy released during an eruption. In this study, we calculate the moment-based magnitude ( M W ) for selected seismic data sets, using different approaches in distinct magnitude ranges to cover the widest possible range of magnitude that characterizes Etna’s seismicity . Specifically , we computed the M W from a data set of moment tensor solutions of earthquakes that occurred in the magnitude range 3.4 ≤M L ≤4.8 during 2005–2020; we created a data set of seismic moment and associated M W for earthquakes 1.0 ≤M L < 3.4 obtained by analysing source spectra; we fine-tuned two relationships, for shallow and deep earthquakes, to obtain M W from response spectra. Finally, we calibrated a specific relationship between M W and M L for the Etna area earthquakes in the range 1.0 ≤M L ≤4.8. All the empirical relationships obtained in this study can be applied in real-time analysis of the seismicity to provide fast and robust information on the released seismic energy.INGV-DPC 2012- 2021 agreement; B2 DPC-INGV 2019-2021 project; IMPACT Department strategic project ; ‘Project PE0000005–RETURN (NRRP)Published2520-2534OST2 Deformazione e Hazard sismico e da maremotoJCR Journa
Advances in our understanding of pyroclastic current behavior from the 1980 eruption sequence of Mount St. Helens volcano (Washington), USA
No full textThis review summarizes what the volcanology community has learned thus far from studying the deposits of pyroclastic currents (PCs) from the 1980 eruption sequence at Mount St. Helens. The review includes mass flow events during the May 18 eruption, including the lateral blast, the afternoon column collapse and boil-over PC activity, and some aspects of the debris avalanche. We also include a summary of PCs generated in the smaller eruptions following the climactic May 18 event. Our objective is to summarize the state of our understanding of PC transport and emplacement mechanisms from the combination of field and laboratory observations, granular flow experiments, and numerical modeling techniques. Specifically, we couple deposit characteristics, experiments, and numerical modeling techniques to critically address the problems of (1) constraining conditions in the flow boundary zone at the time of deposition; (2) the influence of substrate roughness and topography on PC behavior; (3) the prevalence, causes, and consequences of substrate erosion by PCs; and (4) the reconstruction of PC transportation and sedimentation processes from a combination of geophysical and sedimentological observations. We conclude by providing opportunities for future research as our field, experimental, and numerical research techniques advance.Published24OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametriciJCR Journa
RAPPORTO MACROSISMICO SUL TERREMOTO DI GUARDIA (ETNA) DEL 18/05/2023 - ORE 3:22 locali
No full textDescrizione degli effetti di invertibilità e risentimento del terremoto del 18/05/2023, ML 3.2Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione OE, Catania, ItaliaUnpublished1SR TERREMOTI - Sorveglianza Sismica e Allerta Tsunam
Prestazioni di un sistema di allerta rapido: il caso del software PRESTo
No full textThis work was carried out within the 2015 ART-IT project (Early Earthquake Alert in ITaly). Its main purpose is to investigate the performance and the critical issues of an early warning system with particular reference to the PRESTo system (PRobabilistic and Evolutionary early warning SysTem, [Iannacone et al., 2010; Satriano et al., 2011]) whose use has been tested in the framework of the above mentioned project.
The correct operation of an early warning system can effectively guarantee a more effective management of a seismic emergency from the first seconds after the occurrence of a strong earthquake, allowing quick actions to reduce exposure and seismic risk. The work was substantially subdivided into two main steps. A first calibration phase, carried out in the first part of the project and aimed to identify the best values of the software configuration parameters in terms of event triggering and declaration. Once the values of the aforementioned parameters have been identified, the second phase of the work was focused on testing the software in real time configuration, on a test site area and the subsequent evaluation of its performance in terms of declaration and localization capacity. This work focuses mainly on the second part of the experimentation and is aimed describing and summarizing the analysis carried out to evaluate the response of the PRESTo software (and in general of an early warning system) after one year of experimentation and acquisition and highlight any problems and critical issues of the software and more generally of the rapid alert systems.Published1-328T. Sismologia in tempo reale e Early Warning Sismico e da TsunamiJCR Journa