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  • 1
    Publikationsdatum: 2021-02-23
    Beschreibung: The magnetic poles or dip poles are the points on the Earth's surface and circum‐terrestrial area where the magnetic field is vertical, so the horizontal component vanishes. They are not coincident with geomagnetic poles, which are the points where the dipole axis, obtained by analytic models, intersects the Earth's surface, and their instrumental sampling determination from ad hoc ground surveys is difficult due to the harsh environmental conditions and remoteness of the areas where they are located. In this work, we use magnetic field measurements from ESA's Swarm satellites covering 5 years (2015‐2019), and determine the position of the magnetic poles by modelling the yearly average horizontal magnetic field component through analytic 2D Taylor polynomial fit and finding the locations where this component is minimum. The yearly dip poles positions at average satellites geocentric altitudes are also projected at ground level based on WGS84 geodetic reference system. Reliability of our method is evaluated by an optimized Monte Carlo test applied to combined IGRF model and Swarm data. The availability of several years of data allows us to investigate the long term variation and dynamics of the magnetic poles, also in comparison with the results provided by IGRF model (both IGRF12 and IGRF13). Our results agree with the model, in better accordance in the north hemisphere with IGRF13, indicating that both magnetic poles move in the north‐west direction, with a speed of ∼37‐72 km/y (lower in year 2016) for the north dip pole and of ∼5‐9 km/y for the south one.
    Beschreibung: Published
    Beschreibung: e2020JA028513
    Beschreibung: 1A. Geomagnetismo e Paleomagnetismo
    Beschreibung: JCR Journal
    Schlagwort(e): Magnetic poles location ; Swarm satellites ; Magnetic poles drift ; Magnetic anomalies ; Antarctic and Arctic polar regions ; Monte Carlo test ; 04.05. Geomagnetism ; 05.01. Computational geophysics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Publikationsdatum: 2024-01-09
    Beschreibung: The Tonga-Kermadec subduction zone represents one of the most active areas from both seismic and volcanic points of view. Recently, two planetary-scale geophysical events took place there: the 2019 M7.2 earthquake (EQ) with the epicentre in Kermadec Islands (New Zealand) and the astonishing 2022 eruption of Hunga Tonga-Hunga Ha’apai (HTHH) volcano. Based on the Lithosphere-Atmosphere- Ionosphere Coupling (LAIC) models, we analysed the three geolayers with a multiparametric approach to detect any effect on the occasion of the two events, through a comparison aimed at identifying the physics processes that interested phenomena of different nature but in the same tectonic context. For the lithosphere, we conducted a seismic analysis of the sequence culminating with themain shock in Kermadec Islands and the sequence of EQs preceding the HTHH volcanic eruption, in both cases considering the magnitude attributed to the released energy in the lithosphere within the respective Dobrovolsky area. Moving to the above atmosphere, the attention was focused on the parameters—gases, temperature, pressure—possibly influenced by the preparation or the occurrence of the events. Finally, the ionosphere was examined by means of ground and satellite observations, including also magnetic and electric field, finding some interesting anomalous signals in both case studies, in a wide range of temporal and spatial scales. The joint study of the effects seen before, during and after the two events enabled us to clarify the LAIC in this complex context. The observed similarities in the effects of the two geophysical events can be explained by their slightly different manifestations of releasing substantial energy resulting from a shared geodynamic origin. This origin arises from the thermodynamic interplay between a rigid lithosphere and a softer asthenosphere within the Kermadec-Tonga subduction zone, which forms the underlying tectonic context.
    Beschreibung: Published
    Beschreibung: 1267411
    Beschreibung: OSV2: Complessità dei processi vulcanici: approcci multidisciplinari e multiparametrici
    Beschreibung: JCR Journal
    Schlagwort(e): 2019 Kermadec Islands earthquake ; 2022 Hunga Tonga-Hunga Ha’apai eruption ; LAIC models ; Swarm satellites ; CSES-01 satellite ; Kermadec-Tonga subduction area ; 04.08. Volcanology ; 04.06. Seismology
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Einschränkungen Verfügbarkeit
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