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Reconstruction of the subaerial Holocene volcanic activity through paleomagnetic and 14C dating methods: El Hierro (Canary Islands) (2022)

Risica, Gilda ; Di Roberto, Alessio ; Speranza, Fabio ; [weitere]

Elsevier

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Publikationsdatum: 2022-04-01

Beschreibung: Volcanic hazard assessment relies on the accurate knowledge of the eruptive style and recurrence of volcanic eruptions in the past. At El Hierro (Canary Islands) historical and prehistorical records are still poorly defined, and although the island was the location of one of the most recent eruptions (La Restinga, 2011 CE) of the Canarian archipelago, the recent subaerial volcanism is still poorly studied. Information about the age of Holocene volcanic activity as well as the stratigraphy of the deposits is scarce: few eruptions are dated so far, whereas the others are classified as pre-or Holocene events considering lava flow characteristics along the coast. Here, we report on the dating of eleven (M˜na Chamuscada, M˜na del Tesoro, Orchilla, Las Calcosas, M˜na Negra, Lomo Negro, Below Lomo Negro, Cuchillo del Roque, Malpaso Member, and M˜na del Guanche) Holocene subaerial eruptions, distributed along the three rift zones, combining paleomagnetic and 14C methods. We also provide geochemical analyses for nine of them. Results indicate that M˜na Chamuscada and M˜na del Tesoro occurred more recently than previously considered, setting them within the last two thousand years. Conversely, paleomagnetic and 14C ages found for Lomo Negro eruption are consistent with literature data (Villasante- Marcos and Pav´on-Carrasco, 2014) and constrain the occurrence of this event in the XVI century CE. Finally, for Malpaso Member deposits, the two 14C datings obtained by charcoals found below and above the trachytic layer set the eruption during the Holocene epoch, between ~7300 BCE and ~4700 BCE. For the other eruptions, in two cases (Orchilla and Las Calcosas) many possible time windows during the last 14 ka have been found, whereas a few possible ages have been obtained for the others. On the whole, the resulting chronological reconstruction of the recent activity of El Hierro indicates that eruptions occurred unevenly along the three main rifts, with nine eruptions in the WNW rift, six in the NE rift, and four in the SSE rift. We document at least two periods characterized by high eruptive frequency: an old one, between 8000 BCE and 1000 BCE, with eight eruptions, three of which characterized by more evolved compositions (phonotephrite and trachyte), and a recent one, between 1000 BCE and present day, with at least seven eruptions, mainly showing basanite compositions. The new data yield a significant improvement of Holocene eruption chronology, thus are instrumental for a correct evaluation of the volcanic hazard at El Hierro.

Beschreibung: Published

Beschreibung: 107526

Beschreibung: 1A. Geomagnetismo e Paleomagnetismo

Beschreibung: JCR Journal

Schlagwort(e): Paleomagnetism ; El Hierro ; 04.05. Geomagnetism ; 04.08. Volcanology

Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)

Materialart: article

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Aeromagnetism (2022)

Chiappini, Massimo

Elsevier

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Publikationsdatum: 2022-02-10

Beschreibung: The airborne magnetic method was established a few decades ago, as a strong tool in mining and petroleum exploration. Several economically relevant discoveries are often credited to aeromagnetism. Geological reconnaissance and mapping, deep crustal and upper mantle studies, environmental characterization, and national and international security issues can greatly benefit from the aeromagnetic method, as compared with other geophysical prospecting schemes. The rapid rate of coverage and the low cost per unit area explored represent just a few among the many advantages of the technique. Consequently, large-scale airborne magnetic surveys have been carried out in various parts of the globe. The amount of direct discoveries of ore bodies by means of aeromagnetism is impressive. Large magnetic iron deposits found in the early 1960s are in Southern California, Missouri, Nevada, Pennsylvania, Quebec, Ontario, and elsewhere. In the field of petroleum exploration, the method has also been used, although with less direct application. Depth to magnetic basement estimation in sedimentary basins narrows down areas of interest where to conduct exploration surveys in detail by means of more costly methods. The most relevant use of airborne magnetic results is crustal imaging and characterization. Nowadays, geology is interpreted in three dimensions using a digital aeromagnetic map.

Beschreibung: Published

Beschreibung: 675-688

Beschreibung: 1T. Struttura della Terra

Beschreibung: 4T. Sismicità dell'Italia

Beschreibung: 6T. Studi di pericolosità sismica e da maremoto

Beschreibung: 1V. Storia eruttiva

Beschreibung: 2V. Struttura e sistema di alimentazione dei vulcani

Beschreibung: 6V. Pericolosità vulcanica e contributi alla stima del rischio

Beschreibung: 1A. Geomagnetismo e Paleomagnetismo

Beschreibung: 3A. Geofisica marina e osservazioni multiparametriche a fondo mare

Beschreibung: 5A. Ricerche polari e paleoclima

Beschreibung: 7A. Geofisica per il monitoraggio ambientale

Beschreibung: 1TR. Georisorse

Beschreibung: 2TR. Ricostruzione e modellazione della struttura crostale

Beschreibung: 6SR VULCANI – Servizi e ricerca per la società

Beschreibung: 7SR AMBIENTE – Servizi e ricerca per la società

Schlagwort(e): aeromagnetism ; potential fields ; magnetic anomaly ; 04.02. Exploration geophysics ; 04.05. Geomagnetism ; 04.07. Tectonophysics ; 04.08. Volcanology ; 04.06. Seismology

Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)

Materialart: book chapter

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An alternative method to evaluate earthquake detection from synthetic Wood–Anderson seismograms: an application in Italy (2022)

Augliera, Paolo

Oxford University Press

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Publikationsdatum: 2022-08-26

Beschreibung: This article has been accepted for publication in Geophysical Journal International ©: The Authors 2022. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. Uploaded in accordance with the publisher's self-archiving policy.

Beschreibung: Defining the regional variability of minimum magnitude for earthquake detection is crucial for planning seismic networks. Knowing the earthquake detection magnitude values is fundamental for the optimal location of new stations and to select the priority for reactivating the stations of a seismic network in case of a breakdown. In general, the assessment of earthquake detection is performed by analysing seismic noise with spectral or more sophisticated methods. Further, to simulate amplitude values at the recording sites, spectral methods require knowledge of several geophysical parameters including rock density, S-wave velocity, corner frequency, quality factor, site specific decay parameter and so on, as well as a velocity model for the Earth's interior. The simulation results are generally expressed in terms of Mw and therefore a further conversion must be done to obtain the values of local magnitude (ML), which is the parameter commonly used for moderate and small earthquakes in seismic catalogues. Here, the relationship utilized by a seismic network to determine ML is directly applied to obtain the expected amplitude [in mm, as if it were recorded by a Wood–Anderson (WA) seismometer] at the recording site, without any additional assumptions. The station detection estimates are obtained by simply considering the ratio of the expected amplitude with respect to the background noise, also measured in mm. The seismic noise level for the station is estimated starting from four waveforms (each signal lasting 1 min) sampled at various times of the day for a period of one week. The proposed method is tested on Italian seismic events occurring in 2019 by using the locations of 16.879 earthquakes recorded by 374 stations. The first results indicate that by evaluating the station noise level with 5-s windows, a representative sample of the variability in expected noise level is generated for every station, even if only 4 min of signal per day over a week of recordings is used. The method was applied to define the detection level of the Italian National Seismic Network (RSN). The RSN detection level represents a reference for the definition and application of guidelines in the field of monitoring of subsurface industrial activities in Italy. The proposed approach can be successfully applied to define the current performance of a local seismic network (managed by private companies) and to estimate the expected further improvements, requested to fulfil the guidelines with the installation of new seismic stations. This method has been tested in Italy and can be reproduced wherever the local magnitude ML, based on synthetic WA records, is used.

Beschreibung: Published

Beschreibung: 1283–1297

Beschreibung: 4T. Sismicità dell'Italia

Beschreibung: JCR Journal

Schlagwort(e): Time-series analysis ; Earthquake ground motions ; Seismic noise ; Induced seismicity ; 04.06. Seismology ; 05.04. Instrumentation and techniques of general interest

Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)

Materialart: article

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The use of immersive virtual reality for teaching fieldwork skills in complex structural terrains (2022)

Harknett, Jamie ; Whitworth, Malcom ; Rust, Derek ; [weitere]

Elsevier

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Publikationsdatum: 2022-09-15

Beschreibung: Innovations in virtual reality (VR) technology have led to exciting possibilities in teaching earth sciences, allowing students to experience complex geological sites that, due to cost and logistical reasons, they would not normally be able to experience. The need for high quality online digital learning resources and blended learning was brought to the forefront during the SARS-CoV-2 pandemic, as courses with a traditional physical field work component were forced to move online and provide alternatives to students. While it is unlikely that virtual field trips (VFT) would be accepted by students as a replacement of real-world fieldwork moving out of the pandemic, research shows promise that using IVR experiences can lead to enhanced learning outcomes in geosciences, warranting its inclusion on the curricula. This paper presents the outputs of a project to improve student learning in complex geological environments using VR. Here we outline a workflow that was developed to collect high resolution imagery using remote sensing to create digital outcrop models (DOM) of complex geological sites. Using this framework, this paper will then explore the use of VR for an investigation of the Husavik Triple Junction, a complex structural site in northern Iceland, explaining how the drone data was converted to a 3D DOM and demonstrating how VR can be used to simulate real world field mapping. Finally, we describe how these IVR activities have been integrated into taught modules at postgraduate level and discuss how the use of IVR experiences can complement existing geoscience curriculum design.

Beschreibung: Erasmus+ Key Action 2 funded project 2017-1-UK01-KA203-036719 3DTeLC-Bringing the 3Dworld into the classroom: a new approach to Teaching, Learning and Communicating the science of geohazards in terrestrial and marine environments coordinated by M. Whitworth. (https://ec.europa.eu/programmes/erasmus-plus/projects/eplus-projectdetails/#project/2017-1-UK01-KA203-036719and http://www.3dtelc.com) and the MIUR Project ACPR15T4_00098–Argo3D, coordinated by A. Tibaldi (http://argo3d.unimib.it/).

Beschreibung: Published

Beschreibung: 104681

Beschreibung: 1TM. Formazione

Beschreibung: JCR Journal

Schlagwort(e): Virtual reality ; Geosciences ; Teaching ; Fieldwork ; Structural geology ; Digital outcrop model ; 05.04. Instrumentation and techniques of general interest ; 04.04. Geology ; 05.03. Educational, History of Science, Public Issues

Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)

Materialart: article

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Interlaboratory test for chemical analysis of geothermal fluids: A new approach to determine deep geothermal reservoir fluid composition with uncertainty propagation (2022)

Verma, Mahendra P ; Izquiedo, Georgina ; Barth, Johannes A C ; [weitere]

Elsevier

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Publikationsdatum: 2022-10-28

Beschreibung: A representative fluid sampling of surface geothermal manifestations and its analytical data quality assurance and quality control (QA/QC) are challenging aspects of understanding the geothermal reservoir processes. To achieve these goals, an interlaboratory test for the chemical analyses of ten water samples: one synthetic water, two lake waters (i.e., duplicated), one stream water, and six water samples from two geothermal wells of Los Azufres Geothermal field (LAGF), Michoacan, Mexico, was conducted. The geothermal wells were sampled at four points: (1) total discharge of condensed fluid at the wellhead, (2) separate liquid condensed in the well separator, (3) flushed liquid at the weir box, and (4) separated vapor condensed at the well-separator (data taken from Verma et al., 2022). Sixteen laboratories from ten countries reported their results. The pH, electrical conductivity, Ca2+, Li+, SO4 2 B, and Si-total measurements were 8.35 ± 0.04, 12.25 ± 0.53 mS/cm, 25 ± 1 mg/l, 18 ± 1 mg/l, 569 ± 33 mg/l, 320 ± 21 mg/l, and 20.5 ± 0.7 mg/l, which are close to the conventional true values, 8.40, 12.31 mS/cm, 23 mg/l, 19 mg/l, 647 mg/l, 330 mg/l, and 20.0 mg/l, respectively. Analytical errors for major ions, Na+, Cl

Beschreibung: Published

Beschreibung: 105477

Beschreibung: 2IT. Laboratori analitici e sperimentali

Beschreibung: JCR Journal

Schlagwort(e): Geothermal water ; Inter-laboratory test ; Geothermal system ; Los Azufres ; Geochemical modeling ; Uncertainty propagation ; NIST Uncertainty machine ; 05.04. Instrumentation and techniques of general interest

Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)

Materialart: article

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