Abstract:Studying seismicity in a volcanic environment provides important information on the state of activity of volcanoes. The seismicity of the Neapolitan volcanoes, Campi Flegrei, Vesuvius, and Ischia, shows distinctive characteristics for each volcano, covering a wide range of patterns and types. In this study we relocated some significant volcano-tectonic earthquake swarms that occurred in Campi Flegrei and Vesuvius. Moreover, we compared the earthquake occurrence evolution, the magnitude and the seismic energy r… Show more
“…1 a). The completeness magnitude in this dataset is 0.2 to 0.4, and when the background seismic noise is particularly low, this station can record earthquakes with magnitude > − 0.2 67 , 109 , 110 .…”
Section: The Ground Displacement and Seismic Datasets Collected In Cfcmentioning
confidence: 91%
“…The Gutenberg-Richter b-value increased through time—from values smaller than 0.8 in 2014 to values close to 1.3 at the end of 2019 109 ; this may reflect the increasing injection of magmatic fluids into the hydrothermal system and its pressurization 65 , 111 . Several of the seismic swarms in this time interval affected the Solfatara-Pisciarelli area 110 , where has been recorded the greatest increase in the rise of flux of fluids, however many other earthquakes occurred elsewhere, mostly concentrating in a 3 km radius from the center of the caldera 67 . Figure 2 Overview of the earthquakes recorded at Campi Flegrei in 2000–2020.…”
Section: The Ground Displacement and Seismic Datasets Collected In Cfcmentioning
confidence: 91%
“…1a). The completeness magnitude in this dataset is 0.2 to 0.4, and when the background seismic noise is particularly low, this station can record earthquakes with magnitude > − 0.2 67,109,110 . Seismicity typically occurs in CFc during the uplifting phases, whereas it is almost absent during subsidence 77 .…”
mentioning
confidence: 92%
“…In this study, we tackle the problem of the mathematical analysis of the GPS and seismic data by considering the most complete instrumental catalogs of ground displacement and earthquakes in CFc, up to 31/12/2020 27 , 54 , 67 . The main target of our study is measuring and modeling the main features of the geophysical monitoring signals described in terms of temporal rates, Fourier analysis and differential modeling of nonlinear acceleration.…”
Section: Introductionmentioning
confidence: 99%
“…The STH seismic catalog of CFc from 2000 to 2020. The INGV-OV permanent seismic network currently consists of 40 digital stations and 5 analog seismic stations 67 . In this study we consider the 01/2000-12/2020 seismic catalog of Campi Flegrei that is routinely updated by the Osservatorio Vesuviano seismic laboratory 93 .…”
Ongoing resurgence affects Campi Flegrei caldera (Italy) via bradyseism, i.e. a series of ground deformation episodes accompanied by increases in shallow seismicity. In this study, we perform a mathematical analysis of the GPS and seismic data in the instrumental catalogs from 2000 to 2020, and a comparison of them to the preceding data from 1983 to 1999. We clearly identify and characterize two overlying trends, i.e. a decennial-like acceleration and cyclic oscillations with various periods. In particular, we show that all the signals have been accelerating since 2005, and 90–97% of their increase has occurred since 2011, 40–80% since 2018. Nevertheless, the seismic and ground deformation signals evolved differently—the seismic count increased faster than the GPS data since 2011, and even more so since 2015, growing faster than an exponential function The ground deformation has a linearized rate slope, i.e. acceleration, of 0.6 cm/yr2 and 0.3 cm/yr2 from 2000 to 2020, respectively for the vertical (RITE GPS) and the horizontal (ACAE GPS) components. In addition, all annual rates show alternating speed-ups and slow-downs, consistent between the signals. We find seven major rate maxima since 2000, one every 2.8–3.5 years, with secondary maxima at fractions of the intervals. A cycle with longer period of 6.5–9 years is also identified. Finally, we apply the probabilistic failure forecast method, a nonlinear regression that calculates the theoretical time limit of the signals going to infinity (interpreted here as a critical state potentially reached by the volcano), conditional on the continuation of the observed nonlinear accelerations. Since 2000, we perform a retrospective analysis of the temporal evolution of these forecasts which highlight the periods of more intense acceleration. The failure forecast method applied on the seismic count from 2001 to 2020 produces upper time limits of [0, 3, 11] years (corresponding to the 5th, 50th and 95th percentiles, respectively), significantly shorter than those based on the GPS data, e.g. [0, 6, 21] years. Such estimates, only valid under the model assumption of continuation of the ongoing decennial-like acceleration, warn to keep the guard up on the future evolution of Campi Flegrei caldera.
“…1 a). The completeness magnitude in this dataset is 0.2 to 0.4, and when the background seismic noise is particularly low, this station can record earthquakes with magnitude > − 0.2 67 , 109 , 110 .…”
Section: The Ground Displacement and Seismic Datasets Collected In Cfcmentioning
confidence: 91%
“…The Gutenberg-Richter b-value increased through time—from values smaller than 0.8 in 2014 to values close to 1.3 at the end of 2019 109 ; this may reflect the increasing injection of magmatic fluids into the hydrothermal system and its pressurization 65 , 111 . Several of the seismic swarms in this time interval affected the Solfatara-Pisciarelli area 110 , where has been recorded the greatest increase in the rise of flux of fluids, however many other earthquakes occurred elsewhere, mostly concentrating in a 3 km radius from the center of the caldera 67 . Figure 2 Overview of the earthquakes recorded at Campi Flegrei in 2000–2020.…”
Section: The Ground Displacement and Seismic Datasets Collected In Cfcmentioning
confidence: 91%
“…1a). The completeness magnitude in this dataset is 0.2 to 0.4, and when the background seismic noise is particularly low, this station can record earthquakes with magnitude > − 0.2 67,109,110 . Seismicity typically occurs in CFc during the uplifting phases, whereas it is almost absent during subsidence 77 .…”
mentioning
confidence: 92%
“…In this study, we tackle the problem of the mathematical analysis of the GPS and seismic data by considering the most complete instrumental catalogs of ground displacement and earthquakes in CFc, up to 31/12/2020 27 , 54 , 67 . The main target of our study is measuring and modeling the main features of the geophysical monitoring signals described in terms of temporal rates, Fourier analysis and differential modeling of nonlinear acceleration.…”
Section: Introductionmentioning
confidence: 99%
“…The STH seismic catalog of CFc from 2000 to 2020. The INGV-OV permanent seismic network currently consists of 40 digital stations and 5 analog seismic stations 67 . In this study we consider the 01/2000-12/2020 seismic catalog of Campi Flegrei that is routinely updated by the Osservatorio Vesuviano seismic laboratory 93 .…”
Ongoing resurgence affects Campi Flegrei caldera (Italy) via bradyseism, i.e. a series of ground deformation episodes accompanied by increases in shallow seismicity. In this study, we perform a mathematical analysis of the GPS and seismic data in the instrumental catalogs from 2000 to 2020, and a comparison of them to the preceding data from 1983 to 1999. We clearly identify and characterize two overlying trends, i.e. a decennial-like acceleration and cyclic oscillations with various periods. In particular, we show that all the signals have been accelerating since 2005, and 90–97% of their increase has occurred since 2011, 40–80% since 2018. Nevertheless, the seismic and ground deformation signals evolved differently—the seismic count increased faster than the GPS data since 2011, and even more so since 2015, growing faster than an exponential function The ground deformation has a linearized rate slope, i.e. acceleration, of 0.6 cm/yr2 and 0.3 cm/yr2 from 2000 to 2020, respectively for the vertical (RITE GPS) and the horizontal (ACAE GPS) components. In addition, all annual rates show alternating speed-ups and slow-downs, consistent between the signals. We find seven major rate maxima since 2000, one every 2.8–3.5 years, with secondary maxima at fractions of the intervals. A cycle with longer period of 6.5–9 years is also identified. Finally, we apply the probabilistic failure forecast method, a nonlinear regression that calculates the theoretical time limit of the signals going to infinity (interpreted here as a critical state potentially reached by the volcano), conditional on the continuation of the observed nonlinear accelerations. Since 2000, we perform a retrospective analysis of the temporal evolution of these forecasts which highlight the periods of more intense acceleration. The failure forecast method applied on the seismic count from 2001 to 2020 produces upper time limits of [0, 3, 11] years (corresponding to the 5th, 50th and 95th percentiles, respectively), significantly shorter than those based on the GPS data, e.g. [0, 6, 21] years. Such estimates, only valid under the model assumption of continuation of the ongoing decennial-like acceleration, warn to keep the guard up on the future evolution of Campi Flegrei caldera.
Determining the time spans of processes related to the assembly of eruptible magma at active volcanoes is fundamental to understand magma chamber dynamics and assess volcanic hazard. This information can be recorded in the chemical zoning of crystals. Nevertheless, this kind of study is still poorly employed for the active volcanoes of the Neapolitan area (Southern Italy), in particular, for Ischia island where the risk is extremely high and this information can provide the basis for probabilistic volcanic hazard assessment. For these reasons, we acquired chemical composition on clinopyroxene crystals erupted at Ischia during the Zaro eruption (6.6 ± 2.2 ka) and performed numerical simulations of the input of mafic magma into a trachytic reservoir, in order to investigate various aspects of pre-eruptive dynamics occurring at different timescales. This event emplaced a ~ 0.1 km3 lava complex, in which the main trachytic lava flows host abundant mafic to felsic enclaves. Previous petrological investigation suggested that mafic magma(s) mixed/mingled with a trachytic one, before the eruption. In this work, the clinopyroxene zoning patterns depict the growth of crystals in different magmatic environments, recording sequential changes occurred in the plumbing system before the eruption. The evolution of the plumbing system involved a hierarchy of timescales: a few hours for magma mingling caused by mafic recharge(s) and likely occurred multiple times over a decade during which a dominant magmatic environment was sustained before the eruption. Such timescales must be considered in volcanic hazard assessment at Ischia and similar active volcanoes in densely populated areas.
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