DSpace Collection:http://hdl.handle.net/2122/552024-03-29T00:16:53Z2024-03-29T00:16:53ZThe Adriatic Thrust Fault of the 2021 Seismic Sequence Estimated from Accurate Earthquake Locations Using sP Depth PhasesDi Stefano, RaffaeleCiaccio, Maria GraziaBaccheschi, PaolaZhao, Dapenghttp://hdl.handle.net/2122/169162024-03-28T10:14:18Z2023-01-01T00:00:00ZTitle: The Adriatic Thrust Fault of the 2021 Seismic Sequence Estimated from Accurate Earthquake Locations Using sP Depth Phases
Authors: Di Stefano, Raffaele; Ciaccio, Maria Grazia; Baccheschi, Paola; Zhao, Dapeng
Abstract: An earthquake sequence occurred in the Central Adriatic region during March–June 2021.
This sequence started on 27 March with a mainshock of moment magnitude (Mw) 5.2 occurring at 13:47 coordinated universal time (UTC). No foreshock was observed before this
mainshock. The sequence lasted approximately three months, until the end of June
2021. Approximately 200 seismic events were recorded by the regional seismic network
during this time, including four M ≥ 4.0 earthquakes. The 27 March 2021 earthquake
was one of the strongest instrumentally recorded events in the area bounded approximately by the Ancona–Zadar line to the north and the Gargano–Dubrovnik line to the
south. The mainshock originated at a focal depth of 9.9 km. The seismicity spread from
the mainshock up-dip and down-dip along a northeast-dipping plane. Here, we investigate
the geometry of the fault activated by this seismic sequence by using sP depth phases. We
aim to significantly reduce the large uncertainties associated with the hypocentral locations of offshore earthquakes beneath the Adriatic Sea—an area that plays a fundamental
role in the geodynamics of the Mediterranean. These refined earthquake locations also
allow us to make inferences with regards to the seismotectonic context responsible for
the analyzed seismicity, thus identifying a structure (here referred to as the MidAdriatic fault) consisting of a northwest–southeast-striking thrust fault with a ∼ 35° northeast-dipping plane. The use of depth-phase arrival times to constrain off-network event
locations is of particular interest in Italy due to both the peculiar shape of the peninsula
and the extreme scarcity of seafloor stations, the cost and management of which are very
expensive and complex. Here, we present the first attempt to apply this off-network locating technique to the Italian offshore seismicity research with the aim of improving hazard
estimations in these hard-to-monitor regions.2023-01-01T00:00:00ZHydrothermal alteration and physical and mechanical properties of rocks in a volcanic environment: A reviewPereira, Maria LuísaZanon, VittorioFernandes, IsabelPappalardo, LuciaViveiros, Fátimahttp://hdl.handle.net/2122/169152024-03-28T10:09:10Z2024-01-01T00:00:00ZTitle: Hydrothermal alteration and physical and mechanical properties of rocks in a volcanic environment: A review
Authors: Pereira, Maria Luísa; Zanon, Vittorio; Fernandes, Isabel; Pappalardo, Lucia; Viveiros, Fátima
Abstract: Volcanic rocks are the prominent host rocks in geothermal and volcanic systems in general, displaying heterogeneity. Although various external factors such as temperature, pressure, time, fluid chemistry, and subsurface geology have been thoroughly researched regarding the source of hydrothermal minerals in geothermal fields, the effect of hydrothermal alteration on volcanic hosts is still controversial in the literature. This review compiles data on the physical and mechanical properties of the host rocks composing volcanic environments exhibiting hydrothermal alteration or remaining unaltered. The considered data is originated from hydrothermal areas from Kuril-Kamchatka (Russia), Los Humeros (Mexico), Ngatamaraki, Rotokawa, Kawerau and Ohakuri geothermal fields and Mt. Ruapehu, Mt. Taranaki, and Whakaari volcanoes (New Zealand), Solfatara (Italy), Reykjanes, Nesjavellir, and Theistarereykir geothermal fields (Iceland), La Soufrière de Guadeloupe (Caribbean) volcano, and Merapi volcano (Indonesia).
Analysis of average values displayed in several graphical representations and correlations finds that dense rocks (such as lavas and intrusive rocks) exhibit greater competence and lower porosity than fragmental rocks. However, altered dense rocks display greater variability in mechanical properties compared to pyroclastic rocks, primarily influenced by mineral dissolution leading to rock weakening. Exceptions occur for high-temperature hydrothermal alteration, such as advanced silicification and propylitic alteration, with the latter influenced by minor types of alteration. Fragmental rocks have diverse behaviour with the extent of hydrothermal alteration and welding/compaction. According to the compiled data, an overall strengthening of pyroclastic rocks develops as hydrothermal alteration increases, regardless of the type of hydrothermal alteration.
The complexity of hydrothermal systems, the variability shown by different hydrothermal settings and histories in terms of temperature, fluid chemistry and secondary mineral assemblage, and the variety of rock materials with different microstructures contribute to moderate correlations between properties compared to those established in an unaltered state. However, the same trends (linear, nonlinear, positive, negative) are preserved along hydrothermal alteration. This review emphasizes the significance of the type and degree of hydrothermal alteration, along with the rock type and pre-existence of fractures, in shaping the development of alteration in volcanic environments and modifying the properties of host rocks. The relevance of the review relies on the fact that these properties are considered to enhance the productivity of geothermal fields and improve the assessment of volcanic hazards. Future research is expected to expand on this groundwork.2024-01-01T00:00:00ZReal-time mobile GNSS network data acquired during the 2021–2022 unrest at Vulcano islandBonforte, AlessandroAiesi, GianpieroCalvagna, FrancescoConsoli, SalvatorePruiti, LuciaRubonello, AlessioSaraceno, Benedettohttp://hdl.handle.net/2122/169142024-03-27T15:17:31Z2024-03-16T00:00:00ZTitle: Real-time mobile GNSS network data acquired during the 2021–2022 unrest at Vulcano island
Authors: Bonforte, Alessandro; Aiesi, Gianpiero; Calvagna, Francesco; Consoli, Salvatore; Pruiti, Lucia; Rubonello, Alessio; Saraceno, Benedetto
Abstract: At the end of the summer 2021, an increase in CO2 emissions at Vulcano brought an increase in the alert level and, consequently, to the upgrade of the monitoring activities by increasing the number of instruments deployed and the rate of the surveys. One of the new devices installed was a geodetic GNSS mobile network for a real-time and high-frequency monitoring of ground deformation, to increase the detail with respect to the existing permanent network. The mobile stations were initially installed at the northern base of the La Fossa crater, where the highest values of soil degassing were recorded. Two stations were co-located with gravimeters, in order to compare and integrate the data. After this very first period of testing, the mobile GNSS array has been reconfigured, to investigate the mud pool area. Thus, four stations were installed around the degassing area, one of them being in the same site of the gravimeter. Data has been acquired at 1 Hz rate and is used for the weekly reporting to Civil Protection. It was the first experience of a light and quick-to-install geodetic real-time and high-rate GNSS mobile network in this area, and it was the occasion for testing its performance, as well as different approaches for the real-time kinematic (RTK) differential positioning in order to find the most suitable for the ongoing phenomena. Furthermore, direct data communication and archiving in the institutional database have been implemented for immediate querying from the control room tools. We report the experiences collected during the installation phase, site selection, RTK approaches, and ground motion and provide the daily raw data in RINEX format for any future precise postprocessing for the mid- to long-term analyses.2024-03-16T00:00:00ZNew Concept of Smart UAS-GCP: A Tool for Precise Positioning in Remote-Sensing ApplicationsFamiglietti, Nicola AngeloMiele, PietroMemmolo, AntoninoFalco, LuigiCastagnozzi, AngeloMoschillo, RaffaeleGrasso, CarmineMigliazza, RobertSelvaggi, GiulioVicari, Annamariahttp://hdl.handle.net/2122/169132024-03-27T15:00:56Z2024-03-26T00:00:00ZTitle: New Concept of Smart UAS-GCP: A Tool for Precise Positioning in Remote-Sensing Applications
Authors: Famiglietti, Nicola Angelo; Miele, Pietro; Memmolo, Antonino; Falco, Luigi; Castagnozzi, Angelo; Moschillo, Raffaele; Grasso, Carmine; Migliazza, Robert; Selvaggi, Giulio; Vicari, Annamaria
Abstract: Today, ground control points (GCPs) represent indispensable tools for products’ georeferencing in all the techniques concerning remote sensing (RS), particularly in monitoring activities from unmanned aircraft system (UAS) platforms. This work introduces an innovative tool, smart GCPs, which combines different georeferencing procedures, offering a range of advantages. It can serve three fundamental purposes concurrently: (1) as a drone takeoff platform; (2) as a base station, allowing the acquisition of raw global navigation satellite system (GNSS) data for post-processed kinematic (PPK) surveys or by providing real-time GNSS corrections for precision positioning; (3) as a rover in the network real-time kinematic (NRTK) mode, establishing its position in real time with centimetric precision. The prototype has undergone testing in a dedicated study area, yielding good results for all three geodetic correction techniques: PPK, RTK, and GCP, achieving centimeter-level accuracy. Nowadays, this versatile prototype represents a unique external instrument, which is also easily transportable and able to connect to the GNSS RING network, obtaining real-time positioning corrections for a wide range of applications that require precise positioning. This capability is essential for environmental applications that require a multitemporal UAS-based study. When the real-time RING data are accessible to the scientific community operating in RS surveying, this work could be a helpful guide for researchers approaching such investigations.2024-03-26T00:00:00Z