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b map evaluation and on-fault stress state for the Antakya 2023 earthquakes
No full textThe analysis of on-fault seismicity can enlighten the current stress state on the fault itself. Its definition is relevant to individuate fault patches that have not released all the accumulated stress even after the occurrence of a high magnitude earthquake. We use the b value to characterize the stress state on the fault of the Antakya 2023 main events, being b inversely proportional to the stress. The small magnitude seismicity occurring on the maximum slip fault-patches does not allow the b value estimation. This represents a strong indication that the maximum slip zone released most of the stress previously accumulated. Conversely, the lowest b values are located at the bends of the faults and close to the nucleation zone suggesting that, there, still exists not released stress implying that it could be reactivated in the future.Published1596JCR Journa
A target-based approach for multi-hazard assessment: application to volcanic hazards
No full textVolcanic activity is intrinsically a multi-hazard problem. Different phenomena accompanying volcanic activity, such as seismicity, static deformation, lava flows, gas emission and tephra fallout, can be dangerous to the society and economy with a wide range of impacts. Moreover, the physical parameters representing the intensity measure of such hazards are of different nature and therefore their integration in a single analysis is not straightforward. The most frequent approaches for multi-hazard assessment usually start from considering each hazard as the primary subject of the analysis; afterwards, the multi-hazard analysis is generally based on the integration of multiple volcanic hazards independently assessed, often without any effort of harmonization of the results. Afterwards, the final multi-hazard integration is done using different approaches as e.g., the definition of subjective indexes (for example "Low", "Medium" and "High" hazard zones) or by the spatial overlap of hazard maps representing a specific (sometimes termed "reference") scenario. From a decision-maker point of view, these multi-hazard analyses may not be sufficiently informative, and may be biased by the subjective choices taken by the hazard analysts. In this work, we introduce a target-based approach for multi-hazard assessment in which the target (objective) of the analysis is the starting point of the process. The method is implemented using a fully probabilistic approach that allows also propagating epistemic uncertainties (often quantified while evaluating single hazards separately). The approach is based on a system for the solution of "fault trees" and "event trees" called MERGER [1], and involves: (i) the definition of a clear objective for the analysis (i.e., the "target"), which is probably a more clear task for a decision maker; (ii) the identification of hazardous events that can potentially contribute to the achievement of the "target" objective; and (iii) the definition of possible logical relationships between the events that identify the way in which they can contribute to achieving the target objective. As a demonstrator of our approach, we present some preliminary results obtained in the framework of the PANACEA project (INGV's project "Pianeta Dinamico", funded by the Italian Ministero dell'Università e la Ricerca, MUR) regarding the multi-hazard assessment around Mt Etna volcano. In particular, we identify a few target objectives related to mobility disruption due to Mt Etna activity, and we show how the MERGER model can integrate the probabilistic hazard for seismic events, lava flow inundation and tephra fallout.PublishedCataniaOSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametric
Tidal Calibration of the Gladwin Tensor Strain Monitor (GTSM) Array in Taiwan
No full textTo ensure the accuracy and reliability of crustal strain measures, sensors require a thorough calibration. In Taiwan, the complicated dynamics of surface and subsurface hydrological processes under semi-tropical climate conditions conjugated with the rough surface topography could have impacted strainmeter deployment, pushing the installation conditions astray from the optimal ones. Here, we analyze the complex response of 11 Gladwin Strain Monitor (GTSM) strainmeter type deployed in north and central Taiwan and we propose a novel calibration methodology which relies on waveform modeling of Earth and ocean tidal strain-related deformations. The approach is completely data-driven, starting from a simple calibration framework and progressively adding complexity in the model depending on the quality of the data. However, we show that a simple quasi-isotropic model (three calibration factors) is generally suitable to resolve the orientation and calibration of 8 instruments out of 11. We also highlight the difficulty of clearly defining the behavior of instruments that are highly affected by hydrological forcing.In pressOST3 Vicino alla fagliaJCR Journa
Combining Seismotectonic and Catalog-Based 3D Models for Advanced Smoothed Seismicity Computations
No full textThe new generation seismic hazard maps use 3D seismotectonic fault models, which are more consistent with the actual nature of faults, whereas the classical models based on earthquake catalogs only utilize a 2D representation of the seismicity. Although the former provides more reliable information on seismogenic structures, the latter can deliver trustworthy seismicity rates easily. Therefore, it is necessary to combine both the approaches to create a high‐quality seismic hazard assessment model. This study proposes an innovative approach using smoothed seismicity methods that can be advantageous in all contexts with available 3D fault models and high‐quality seismic catalogs. We applied our method on the Adriatic Basal Thrust (ABT) in eastern central Italy—a lithospheric‐scale active contractional structure with a well‐constrained 3D geometric–kinematic reconstruction and a related high‐quality catalog. Our new 3D algorithm was applied to smooth the ABT seismicity on the grid, resulting in a 3D earthquake rate model that also provides rupture parameters such as strike, dip, rake, and seismogenic thickness. Our approach is particularly useful for complex seismotectonic settings, such as in cases of lithospheric shear zones, subduction planes, and overlapping multidepth seismogenic volumes.Published10-20OST2 Deformazione e Hazard sismico e da maremotoJCR Journa
Lithospheric, atmospheric and ionosphere coupling mechanism related to the seismic activity: preliminary results
No full textIn recent years, the accumulated evidence of co-seismic ionospheric signatures of large seismic events led to an increasing scientific interest in the coupling mechanisms, related to seismic activity. Aimed at a deeper understanding and modeling of the interplay processes, the integration of data acquired by both satellites and on-ground devices is crucial. Here, we compare the atmospheric fluctuations in response to moderate and large (M>5) earthquakes. This work is born in the framework of the project Prin2022 funded MIUR, which aims to develop a Lithospheric-Atmospheric-Ionospheric Coupling (LAIC) analytical model. The fluctuations that depend on the parameters of the earthquake source inside the lithosphere are expected to drive atmospheric waves that propagate toward the high atmosphere, generating a co-seismic signature of earthquakes.
The first approach in calibrating the model is to compare the static ground displacement and coseismic deformation field associated with the earthquakes with the observed deformation data (GNSS). Specifically, we focused the attention on the strongest earthquake occurred in Italy close to the city of Norcia provoking severe damages in October 2016, also considering the related aftershocks. Following the approach of Okada, we estimated the static displacement due to Norcia earthquake fault, considering a homogeneous elastic and Poissonian half-space model. For such a scope, we adopted the Coulomb software, developed in Matlab environment, intending to compare the estimated static field with the deformation (GNSS) measurements. We took the specific information about the fault parameters and cinematics regarding the selected earthquakes from the catalog of ESM (Engineering Strong Motion Database, https://esm-db.eu/).
We found that the estimated values of the static displacements are compatible with those observed, opening the route to a well-founded LAIC model.PublishedCorfù (Greece)OST1 Alla ricerca dei Motori GeodinamiciOSA1: Variazioni del campo magnetico terrestre, imaging crostale e sicurezza del territori
The 8 September 2023, MW 6.8, Morocco Earthquake: A Deep Transpressive Faulting Along the Active High Atlas Mountain Belt
No full textOn 8 September 2023 an MW 6.8 earthquake struck the High Atlas Mountains of western Morocco, about 70 km southwest from Marrakesh, causing significant devastation and casualties. In this study, we investigate a comprehensive geodetic data set, employing interferometric synthetic aperture radar measurements to assess the fault segment responsible for the seismic event. Our findings suggest two potential fault scenarios: either a transpressive NNW-dipping high-angle (70°) fault related to the Tizi n'Test alignment or a transpressive SSW-dipping low-angle (22°) fault associated with the North Atlas Fault, with slip (up to 2.2 m) only occurring on deeper parts of the fault. While seismic catalogs couldn't definitively determine the dip direction of the fault, evidence from mainshock locations, gravity and heat flow data and modeling, and active shortening direction suggest the activation of a low-angle south-westerly dipping oblique thrust of the North Atlas fault during the 2023 Moroccan earthquake.Publishede2023GL106992OST3 Vicino alla fagliaJCR Journa
Low-cost MEMS accelerometers for earthquake early warning systems: A dataset collected during seismic events in central Italy
No full textThis article describes a dataset of acceleration signals acquired from a low-cost Wireless Sensor Network (WSN) during seismic events that occurred in Central Italy. The WSN consists of 5 low-cost sensor nodes, each embedding an ADXL355 tri-axial MEMS accelerometer with a fixed sampling frequency of 250 Hz. The data was acquired from February 2023 to the end of June 2023. During this period, several earthquake sequences affected the area where the sensor network was installed. Continuous data was acquired from the WSN and then trimmed around the origin time of seismic events that occurred near the installation site, close to the city of Pollenza (MC), Italy. A total of 67 events were selected, whose data is available at the Istituto Nazionale di Geofisica e Vulcanologia (INGV) Seismology data center. The traces acquired from the WSN were then manually annotated by analysts from INGV. Annotations include picking time for P and S phases, when distinguishable from the background noise, alongside an associated uncertainty level for the manual annotations. The resulting dataset consists of 328 3 × 25,001 arrays, each associated with its metadata. The metadata includes event data (hypocenter position, origin time, magnitude, magnitude type, etc.), trace-related data (mean, median, maximum, and minimum amplitudes, manual picks, and picks uncertainty), and sensor-specific data (sensor name, sensitivity, and orientation). Furthermore, a small dataset consisting of non-seismic traces is included, with the goal of providing records of noise-only traces, relative to both electronic and environmental/anthropic noise sources. The dataset holds potential for training and developing Machine Learning or signal processing algorithms for seismic data with low signal-to-noise ratios. Additionally, it is valuable for research about earthquakes, structural health monitoring, and MEMS accelerometer performance in civil and seismic engineering applications.Published110174OST5 Verso un nuovo MonitoraggioJCR Journa
Sea level rise and extreme events along the Mediterranean coasts: the case of Venice and the awareness of local population, stakeholders and policy makers
No full textSea level rise (SLR) is among the major climate change effects threating the coasts of the Mediterranean basin, which are increasingly exposed to coastal flooding, especially along the low lying coastal plains, river deltas, lagoons and reclama- tion areas. Coastal erosion, beach retreat and marine flooding are already causing unprecedented environmental and socio- economic impacts on coastal populations. According to the Intergovernmental Panel on Climate Change (IPCC) these effects are expected to worsen by 2100 and beyond with a projected global SLR up to about 1 m above the current level. This study provides an overview of the Mediterranean basin, focusing on the vulnerable city of Venice, which is particularly exposed to marine flooding due to SLR and land subsidence. We show the current and future sea level trend as well as a flooding scenarios in the absence of the Experimental Electromechanical Module (MoSE), which is protecting the city of Venice since 2020. To understand the awareness of citizens in Venice to address SLR, we have engaged a group of stakeholders through a structured participatory process to develop solution-oriented, case-specific and site-specific Policy Tools. Our results show that the Policy Tools contain relevant, effective and implementable actions stemming from stakeholder interaction and consensus building, identifying relevant issues that should be considered for SLR adaptation policies. A more extensive participation in public processes is required to materialize the Policy Tools into concrete actions to help vulnerable areas adapt to the expected SLR by the end of this century.Published359–370OSA4: Ambiente marino, fascia costiera ed Oceanografia operativaJCR Journa
CO2 Flushing Triggers Paroxysmal Eruptions at Open Conduit Basaltic Volcanoes
No full textOpen conduit volcanoes erupt with the highest frequency on Earth. Their activity is characterized by an outgassing flux that largely exceeds the gas that could be released by the erupted magma; and by frequent small explosions intercalated by larger events that pose a significant risk to locals, tourists, and scientists. Thus, identifying the signs of an impending larger explosion is of utmost importance for the mitigation of volcanic hazard. Larger explosive events have been associated with the sudden ascent of volatile rich magmas, however, where and why magma accumulates within the plumbing system remains unclear. Here we show that the interaction between CO2-rich fluids and magma spontaneously leads to the accumulation of volatile-rich, low density and gravitationally unstable magma at depth, without the requirement of permeability barriers. CO2-flushing forces the exsolution of water and the increase of magma viscosity, which proceeds from the bottom of the magma column upward. This rheological configuration unavoidably leads to the progressive thickening of a gas-rich and low density (i.e., gravitationally unstable) layer at the bottom of the feeding system. Our calculations account for observations, gas monitoring and petrological data; moreover, they provide a basis to trace the approach to deeply triggered large or paroxysmal eruptions and estimate their size from monitoring data. Our model is finally applied to Stromboli volcano, an emblematic example of open conduit volcano, but can be applied to any other open conduit volcano globally and offers a framework to anticipate the occurrence of unexpectedly large eruptions.Publishede2023JB028486OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametriciJCR Journa
Crustal uplift rates implied by synchronously investigating Late Quaternary marine terraces in the Milazzo Peninsula, Northeast Sicily, Italy
No full textLate Quaternary crustal uplift is well recognized in northeast Sicily, southern Italy, a region also prone to damaging earthquakes such as the 1908 “Messina” earthquake (Mw 7.1), the deadliest seismic event reported within the Italian Earthquake Catalogue. Yet it is still understudied if, within the Milazzo Peninsula, crustal uplift rates are varying spatially and temporally and whether they may be either influenced by (i) local upper-plate faulting activity or (ii) deep geodynamic processes.
To investigate the long-term crustal vertical movements in northeast Sicily, we have mapped a flight of Middle-Late Pleistocene marine terraces within the Milazzo Peninsula and in its southern area and refined their chronology, using a synchronous correlation approach driven by published age controls. This has allowed a new calculation of the associated crustal uplift rates, along a north–south oriented coastal-parallel transect within the investigated area. Our results show a decreasing uplift rate from south to north across the Milazzo Peninsula and beyond, and that the associated rates of uplift have been constant through the Late Quaternary. This spatially varying yet temporally constant vertical deformation helps to constrain the amount of uplift, allowing us to explore which is the driving mechanism(s), proposing a few related scenarios.
We discuss our results in terms of tectonic implications and emphasize the importance of using appropriate approaches, as such applying a synchronous correlation method, to refine chronologies of undated palaeoshorelines when used for tectonic investigations.Published3555-3574OST2 Deformazione e Hazard sismico e da maremotoJCR Journa