Muzellec, Titouan (2024) 4D medium properties variations and fluid influence: application to the 2014 Northern Nagano (Japan) earthquake sequence. [Tesi di dottorato]
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| Tipologia del documento: | Tesi di dottorato |
|---|---|
| Lingua: | English |
| Titolo: | 4D medium properties variations and fluid influence: application to the 2014 Northern Nagano (Japan) earthquake sequence |
| Autori: | Autore Email Muzellec, Titouan titouan.muzellec@unina.it |
| Data: | 4 Marzo 2024 |
| Numero di pagine: | 141 |
| Istituzione: | Università degli Studi di Napoli Federico II |
| Dipartimento: | Strutture per l'Ingegneria e l'Architettura |
| Dottorato: | Ingegneria strutturale, geotecnica e rischio sismico |
| Ciclo di dottorato: | 36 |
| Coordinatore del Corso di dottorato: | nome email Iervolino, Iunio iunio.iervolino@unina.it |
| Tutor: | nome email Zollo, Aldo [non definito] De Landro, Grazia [non definito] |
| Data: | 4 Marzo 2024 |
| Numero di pagine: | 141 |
| Parole chiave: | The region of Nagano (Japan) prefecture is seismically active region characterized by the complexities in the shallow crust of the Itoigawa-Shizuoka fault system, going across Honshu Island, in response of the geodynamics of the subduction zone at the Japan trench. The last major magnitude earthquake, Mw 6.2, which occurred on the 22nd of November 2014 produced damage on infrastructures. The earthquake sequence related to this mainshock provides an opportunity to rethink the geometrical complexities of the roughly N-S striking Itoigawa-Shizuoka fault, their impact on the fault rupture nucleation and development, and the related medium properties variations during the earthquake sequence in the studied region. In the framework, the present thesis work would contribute to improve the knowledge of the spatio-temporal variations of the medium properties and the relationship between the complexity of the fault segmentation and the earthquake rupture, the seismicity location, and the velocity models for this area. To these aims, several processing steps has been followed. The first is focused on the establishment of a procedure to refine the seismic phases identification. The developed refinement picking procedure improve the quality of the picks on the polarized waveforms at the single station by creating families based on the waveform similarity and hierarchical clustering. The second processing step is focused on the travel-time tomography inversion strategy to improve the quality of the velocity models and earthquake locations based on the refined picks catalog. A linearized, damped, tomographic approach has been used in which both refined P- and S-wave arrival times are simultaneously inverted for to estimate the hypocenter and velocity parameters. The inversion strategy is based on a multiscale approach which inverted the observed data with a decreasing spacing of the grid. The third step is focused on the double difference location procedure, to infer higher earthquake location quality, based on the initial location in a three-dimensional velocity model estimated by travel-time tomography and couple of events from the same family estimated by the refinement picking procedure. All these processing steps improve the quality of the earthquake location and allow to infer the complexity of the fault system geometry and estimate the velocity variations at different scale in the region of the earthquake sequence. |
| Settori scientifico-disciplinari del MIUR: | Area 04 - Scienze della terra > GEO/10 - Geofisica della terra solida |
| Depositato il: | 15 Mar 2024 09:57 |
| Ultima modifica: | 14 Apr 2026 07:00 |
| URI: | http://www.fedoa.unina.it/id/eprint/15566 |
Abstract
The region of Nagano (Japan) prefecture is seismically active region characterized by the complexities in the shallow crust of the Itoigawa-Shizuoka fault system, going across Honshu Island, in response of the geodynamics of the subduction zone at the Japan trench. The last major magnitude earthquake, Mw 6.2, which occurred on the 22nd of November 2014 produced damage on infrastructures. The earthquake sequence related to this mainshock provides an opportunity to rethink the geometrical complexities of the roughly N-S striking Itoigawa-Shizuoka fault, their impact on the fault rupture nucleation and development, and the related medium properties variations during the earthquake sequence in the studied region. In the framework, the present thesis work would contribute to improve the knowledge of the spatio-temporal variations of the medium properties and the relationship between the complexity of the fault segmentation and the earthquake rupture, the seismicity location, and the velocity models for this area. To these aims, several processing steps has been followed. The first is focused on the establishment of a procedure to refine the seismic phases identification. The developed refinement picking procedure improve the quality of the picks on the polarized waveforms at the single station by creating families based on the waveform similarity and hierarchical clustering. The second processing step is focused on the travel-time tomography inversion strategy to improve the quality of the velocity models and earthquake locations based on the refined picks catalog. A linearized, damped, tomographic approach has been used in which both refined P- and S-wave arrival times are simultaneously inverted for to estimate the hypocenter and velocity parameters. The inversion strategy is based on a multiscale approach which inverted the observed data with a decreasing spacing of the grid. The third step is focused on the double difference location procedure, to infer higher earthquake location quality, based on the initial location in a three-dimensional velocity model estimated by travel-time tomography and couple of events from the same family estimated by the refinement picking procedure. All these processing steps improve the quality of the earthquake location and allow to infer the complexity of the fault system geometry and estimate the velocity variations at different scale in the region of the earthquake sequence.
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