Coseismic displacements on Ischia island, real-time GPS positioning constraints on earthquake source location

Devoti, R.; Martino, Prospero De; Pietrantonio, Grazia; Dolce, M.

doi:10.4401/ag-7656

Cited by 13 publications

(16 citation statements)

References 16 publications

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“…Station positions are routinely computed and updated at daily rates. The precise processing routine demands standard products delivered by the International GNSS Service (IGS) with a latency of about 2 weeks, the most relevant being, precise orbits, satellite clock corrections, and Earth rotation parameters (Devoti et al, ). The obtained coseismic displacements and further processing details are described in Devoti et al ().…”

Section: Datamentioning

confidence: 99%

“…The MEPO station records vertical displacement of ‐1 cm. A full description of GNSS data, methods, and results is reported by Devoti et al (). Concerning DInSAR measurements, all line‐of‐sight displacement maps (Figure ) show a negative displacement lobe (movements away from the satellite sensors) up to ‐4 cm between Casamicciola Terme and Mt.…”

Section: Coseismic Ground Deformations and Modelingmentioning

confidence: 99%

“…The mechanism responsible for this earthquake is highly debated, and different interpretations are proposed. Some studies invoke the activation of an E‐W, south dipping fault (De Novellis et al, ) or a subhorizontal NW‐SE striking one, both located near the area of maximum damage (Devoti et al, ). Field studies on the brittle deformation produced by the earthquake (Nappi et al, ) suggest the activation of a north‐dipping, E‐W striking fault.…”

Section: Introductionmentioning

confidence: 99%

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Seismic and Geodetic Evidences of a Hydrothermal Source in the Md 4.0, 2017, Ischia Earthquake (Italy)

et al. 2019

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Seismic events characterize active hydrothermal and volcanic areas and may be due to magma/fluid migration, hydrothermal pressurization, gravitational instability, and local tectonics. On 21 August 2017, an M d 4.0 earthquake occurred at Ischia volcanic island (Italy), within an active hydrothermal system. We analyze seismic, Global Positioning System, and interferometric synthetic aperture radar data to shed light on the source mechanism of such an event. The low-frequency content (2 Hz), the low stress drop (0.01 MPa), and a low S/P spectral ratio suggest the involvement of fluids in the source mechanism. The focal mechanism suggests a mixed shear-tensile (opening) rupture with the P first arrivals showing up movements in the nearest stations. Geodetic data describe an E-W elongated area of coseismic subsidence overlapping a WSW-ENE fault bounding the hydrothermal reservoir at depth. The modeled deformation field is consistent with a two-source model consisting of a WSW-ESE striking, north dipping normal fault, and a closing subhorizontal crack. This closure immediately followed an initial opening related to a fluid pressurization event responsible for the earthquake. We show that moderate magnitude earthquakes in active hydrothermal areas may be associated with the pressurization/depressurization cycles of a hydrothermal reservoir due to self-sealing processes and not to the arrival of new fluids from depth. Other events like that recorded at Ischia, which have affected the island in historical times, are not necessarily associated with 'volcanic unrest' episodes and imply the occurrence of fault-valve mechanisms. Therefore, the dynamics of hydrothermal systems must be taken into account in the seismic hazard evaluation.

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Section: Datamentioning

confidence: 99%

Section: Coseismic Ground Deformations and Modelingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Seismic and Geodetic Evidences of a Hydrothermal Source in the Md 4.0, 2017, Ischia Earthquake (Italy)

et al. 2019

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“…Epomeo, possibly originated by a magmatic intrusion (Orsi et al, 1991). As a result of a complex interaction among ground deformation, volcano-tectonic dynamics and underground fluid circulations, Ischia hosts a geothermal system whose surface manifestations consist in both fumaroles' activity and thermal springs (Di Napoli et al, 2009Carlino et al, 2014; Giuseppe et al, 2017;Piochi et al, 2019). The geothermal fluids are a mixing of meteoric, sea water, as well as thermal fluids rising from distinct superimposed reservoirs at depths ranging from 150 up to 1000 m b.s.l.…”

Section: Introductionmentioning

confidence: 99%

“…In the last years, the seismic activity has been low, but on 21 August 2017 (18:57 UTC) a M d 4.0 (M w 3.9) earthquake struck the northern sector of the island, causing two fatalities and many damages in the Casamicciola area. The earthquake (hereinafter referred to IE17) triggered a significant ground displacement (Devoti et al, 2018) and tilting (Ricco et al, 2019) and it was followed by a sequence of about 20 aftershocks (Nappi et al, 2018) located at shallow depths (< 2.5 km b.s.l.). The interpretation of the source process of the IE17 is still controversial: re-activation caused by tectonic stress of an E-W striking fault with south (De Novellis et al, 2018) or north (Nappi et al, 2018) dipping, or complex rupture involving a normal faulting event triggering a shallow underground collapse (Braun et al, 2018), are some of the possi-ble generation mechanisms that have been proposed.…”

Section: Introductionmentioning

confidence: 99%

Characterization of the seismic dynamical state through joint analysis of earthquakes and seismic noise: the example of Ischia Volcanic Island (Italy)

et al. 2020

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This work is devoted to the study of both earthquakes and background seismic noise at Ischia Island (Italy) recorded pre and post the M d 4.0 earthquake occurred on 21 August 2017 (18:57 UTC). We compare and characterize noise and earthquakes in terms of Independent Component Analysis, energy and polarization properties. The earthquakes' waveforms and the background noise are decomposed into a few independent components with two main common signals peaked around 1-2 and 3-4 Hz, respectively. A slight increase of the energy of the background seismic noise is observed comparing samples recorded in 2016 and 2017, whereas no variations are detected in 2017 pre and post the main earthquake. The polarization analysis, performed in the frequency bands individuated by Independent Component Analysis and applied to the background seismic noise, indicates a shallow propagation and the azimuthal pattern is mainly controlled by the local structural features. These results suggest that noise and earthquakes are ascribable to a common phenomenon of fluid-solid interaction in the hydrothermal system of Ischia Island.

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Dynamics of the Neapolitan Volcanoes Inferred from Tiltmeter and Seismic Data Analysis: A Review

Falanga,

Aquino,

Cusano

et al. 2024

Pure Appl. Geophys.

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Coseismic displacements on Ischia island, real-time GPS positioning constraints on earthquake source location

Cited by 13 publications

References 16 publications

Seismic and Geodetic Evidences of a Hydrothermal Source in the Md 4.0, 2017, Ischia Earthquake (Italy)

Seismic and Geodetic Evidences of a Hydrothermal Source in the Md 4.0, 2017, Ischia Earthquake (Italy)

Characterization of the seismic dynamical state through joint analysis of earthquakes and seismic noise: the example of Ischia Volcanic Island (Italy)

Dynamics of the Neapolitan Volcanoes Inferred from Tiltmeter and Seismic Data Analysis: A Review

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