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Di Giovambattista, Rita
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Preferred name
Di Giovambattista, Rita
Email
rita.digiovambattista@ingv.it
Staff
staff
ORCID
Scopus Author ID
6603807120
Researcher ID
L-5747-2015
60 results
Now showing 1 - 10 of 60
- PublicationRestrictedSeismic and Geodetic Evidences of a Hydrothermal Source in the Md 4.0, 2017, Ischia Earthquake (Italy)(2019-05-02)
; ; ; ; ; ; ; ; ; ; ; ; ; 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 Md 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 offluids 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.467 7 - PublicationOpen AccessAmplitude response of a telemetered seismic system from seismometers to digital acquisition system(1995-03)
; ; ; ;Di Giovambattista, R.; Istituto Nazionale di Geofisica, Roma, Italy ;Barba, S.; Istituto Nazionale di Geofisica, Roma, Italy ;Marchetti, A.; Istituto Nazionale di Geofisica, Roma, Italy; ; Automated amplitude response of the complete seismometer, telemetry and recording system js obtaiued trom sinusoidal inputs to the calibration coil. Custom-built software was designed to perform fully automatic cali- bration analyses of the digital signals. In this paper we describe the signals used for calibration and interactive and batch procedures designed to obtain calibration functions in automatic mode. By using a steady-state method we reach a high degree of accuracy in the determination of both the frequency and amplitude of the \ignal. The only parameters required by this procedure are the seismometer mass, the calibration-coil constant and the intensity of the current injected into the calibration coil. This procedure is applicable to telemetered seismic systems and represents an optimization of the processing time. The software was designed to requjre no modification" jf the device used to generate the sinusoidal current should change. In particular, it is possi- ble to changc the number of monotrequcncy packages transmitted to the calibration coil with the on]y restric- tion that the difference between the frequency of two consecutjve packages be greater than 5%; for these rea- sons the procedure is expected to be usefu] for the seismological community. The paper inc]udes a generaI de- scription of thc designing criteria, and of the hardware and software architecture, as well as an account of thc system's performancc during a two year period of operation.178 158 - PublicationEmbargoInvestigating the Role of Fluids in the Source Parameters of the 2013–2014 Mw 5 Matese Seismic Sequence, Southern Italy(2024)
; ; ; ; ; We investigate the variability of Brune stress drop (Δσ), apparent stress (τa), and Savage– Wood radiation efficiency (ηsw τa= Δσ), in the 2013–2014 Mw 5.0 earthquake sequence that struck the Matese area in the southern Apennines range of Italy. The sequence is clustered in a relatively small crustal volume in the 13–22 km depth range, which is greater than that of background seismicity and normal-faulting sequences that occurred under the range axis, usually located in the first 15 km of the crust.We find high Savage– Wood radiation efficiency values for most of the analyzed earthquakes located in a narrow crustal volume, with values ranging from well above the self-similarity value to very high values as high as 0.55. In addition, a large variability in radiation efficiency (up to 90%) is observed for two similar magnitude events at different depths. Previous studies reported seismic evidence of fluid involvement in the nucleation process of the Matese earthquakes. By integrating our results with crustal geophysical data published recently, we propose that most of the earthquakes characterized by high values of ηsw are nucleated within high pore pressure zones located in the crystalline midcrust of Adria. We reckon that high pore pressure fluids of deep origin played a role in the rupture process and were responsible for themixed shear-tensile sources inferred from the analysis of the S-wave/P-wave spectral amplitude ratio for most of 2013–2014 earthquakes.46 7 - PublicationOpen AccessFault-trapped waves depict continuity of the fault system responsible for the 6 April 2009 MW 6.3 L’Aquila earthquake, central Italy(2012)
; ; ; ; ; ;Calderoni, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Di Giovambattista, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Vannoli, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Pucillo, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Rovelli, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; ; ; We investigate fault-trapped waves observed at a permanent broad-band station (FAGN) installed on the San Demetrio Fault, about 20 km southeast of L'Aquila. This fault has the same strike of the Paganica Fault which was responsible for the MW 6.3, 6 April 2009 earthquake. The two faults display an en-echelon pattern with a few km offset. We have found that events causing efficient trapped waves are clustered at the northwestern and southeastern bottom ends of the ruptured Paganica fault plane. The efficiency of trapped waves at FAGN, which is located about 5 km far from the ruptured fault plane, indicates that the two faults are linked at depth. This suggests that fault segments in the study area can be part of a longer and continuous fault system which controls the seismic hazard of the region. Moreover, we have found that the two earthquake clusters generating the most efficient trapped waves occur in portions of the fault system with the highest fluid pressure.581 416 - PublicationOpen AccessRupture Directivity of the Strongest 2016-2017 Central Italy Earthquakes(2017)
; ; ; ; ; The along‐strike rupture directivity of 16 of the strongest earthquakes (4.4 ≤ Mw ≤ 6.5) within the 2016–2017 central Italy seismic sequence is estimated by investigating high‐frequency S wave amplitude variations versus source azimuths with an empirical Green's function deconvolution approach. The results confirm that an along‐strike rupture directivity is a persistent feature of normal‐faulting earthquakes in the Apennines. The preferred rupture directions of the 2016–2017 earthquakes and of similar‐magnitude events from the 1997 Umbria‐Marche and 2009 L'Aquila‐Campotosto seismic sequences show a significant spatial consistency. Different sectors of the Apennines show an alternating trend of preferential along‐strike rupture propagation directions with significant spatial and temporal stabilities independent of the magnitude. These results, if confirmed by further data, could lead to more refined hazard assessments of the investigated region.148 46 - PublicationOpen AccessForecasting strong subsequent earthquakes in California clusters by machine learningIn this paper, we propose an innovative machine learning approach called NESTORE, which analyses seismic clusters to forecast strong earthquakes of magnitudes similar or greater to those of the mainshock. The method analyzes the seismicity in the first hours/days after the mainshock and provides the probability of having a strong subsequent earthquake. The analysis is conducted at various stages of time to simulate the increase in knowledge over time. We address the main problem of statistics and machine learning when applied to spatiotemporal variation of seismicity: the small datasets available, on the order of tens or fewer instances, need a more accurate analysis with respect to the classical testing procedures, where hundreds or thousands of data are available. In addition, we develop a more robust NESTORE method based on a jackknife approach (rNESTORE), and we successfully apply it to California seismicity.
36 27 - PublicationOpen AccessThe fine structure of the dynamics of seismicity before earthquakes in the area of Reggio Emilia (Northern Italy)(1999-10)
; ; ;Di Giovambattista, R.; Istituto Nazionale di Geofisica, Roma, Italy ;Tyupki, Y.; Geophysical Center, Russian Academy of Sciences, Moscow, Russia; We present the results of studies of seismicity in the Reggio Emilia area (Northern Italy). The Istituto Nazionale di Geofisica instrumental earthquake catalogue (1975-1996) reported about three moderate-size earthquakes with M ³ 4.5 that occurred in this area (November 1983, May 1987, October 1996). The RTL prognostic parameter proposed by Sobolev and Tyupkin (1996a) was used for analysis. This parameter is designed in such a way that a seismic quiescence produces negative anomaly of the RTL parameter in comparison to its perennial background level and an activation of seismicity initiates the growth of its value. The RTL prognostic parameter indicates that all three earthquakes are preceded by activation of the seismicity. The interval between the commencement of the activation identified by RTL parameter and the event itself was about one year for the 1987 and 1996 earthquakes, and about three months for the 1983 earthquake.154 204 - PublicationOpen AccessPianificazione e gestione di un’emergenza sismica: esercitazione INGV del 26 novembre 2015 effettuata nell’ambito della Linea di Attività T5 “Sorveglianza sismica e operatività post terremoto”(INGV, 2016)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Pondrelli, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Bologna, Bologna, Italia ;Amato, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Massa, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia ;Montone, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Crescimbene, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;La Longa, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; Nella Struttura Terremoti dell’INGV la Linea di Attività T5 “Sorveglianza sismica ed operatività postterremoto” si occupa delle attività di sviluppo di strumenti e procedure per la valutazione in tempo reale degli effetti di terremoti e tsunami e della gestione delle emergenze sismiche. Uno dei suoi obiettivi del 2015 era la formalizzazione dei protocolli di intervento di Gruppi d’Emergenza, avvenuta per Emergeo, Emersito, IES, QUEST e Sismiko con Decreto del Presidente nel luglio 2015. Altro obiettivo era l’elaborazione di un Protocollo di Ente per la gestione delle emergenze sismiche. La bozza preparata nel 2015 prevede l’importante novità dell’Unità di Crisi, mai formalizzata in precedenza. Attraverso questo Protocollo di Ente si auspica di migliorare la risposta logistico-operativa dell’INGV durante l’emergenza, di avere una più rapida conoscenza del fenomeno in corso e di realizzare un’efficace comunicazione verso Protezione Civile, media e pubblico. Per verificare il tutto è stata organizzata un’esercitazione in cui è stato simulato un terremoto di magnitudo 6.4 nel basso Lazio. Si sono così sperimentate l’efficacia del flusso azioni/informazioni durante un’emergenza, il funzionamento dell’Unità di Crisi, la funzionalità dei protocolli dei Gruppi d’Emergenza, l’efficienza delle attività in sede per gli aspetti tecnico-logistici, il flusso di comunicazione interno e le comunicazioni istituzionali esterne (queste ultime simulate). In questo articolo sono descritte le fasi di organizzazione ed attuazione dell’esercitazione. Inoltre, durante il suo svolgimento, la valutazione dell’efficacia dell’organizzazione e delle attività svolte dai gruppi coinvolti è stata affidata ad alcuni osservatori e qui è allegata l’elaborazione dei commenti riportati. Abbiamo fatto infine una sintesi dei risultati positivi e delle criticità emerse dall’esercitazione, attività così importante a nostro avviso da considerarne indispensabile la ripetizione con cadenza quanto meno annuale.3550 438 - PublicationOpen AccessLarge amplitude variations recorded by an on-fault seismological station during the L’Aquila earthquakes: evidence for a complex fault-induced site effect(2010-12-17)
; ; ; ;Calderoni, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Rovelli, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Di Giovambattista, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; ; This study is focused on amplification effects observed at an on-fault station, FAGN, near L’Aquila. The difference in amplitude, compared to nearby stations, is extremely large for some particular events and neigligible for others of the same seismic sequence. FAGN is located on the S. Demetrio fault (Vezzani and Ghisetti, 1998) and the presence of the fault zone beneath the station could play a role on the observed amplifications (Davis et al., 2000; Cultrera et al., 2003; Karabulut and Bouchon, 2007). The fault-guided propagation effect is investigated through numerical modeling and analytical solutions by Ben-Zion and Aki (1990) and Ben-Zion (1998).141 124 - PublicationOpen AccessSTRESS PARAMETERS OF REPEATING EARTHQUAKES IN THE NUCLEATION VOLUME OF THE APRIL 6, 2009, MW 6.1 L'AQUILA EARTHQUAKE(2018-09)
; ; ; ; ; We analyze the state of stress for 28 repeaters, foreshocks, mainshock and aftershocks, in the rupture nucleation volume of the destructive L’Aquila earthquake including the strongest Mw4.1 foreshock occurred one week before the mainshock. In a previous paper, earthquakes clustered in this crustal volume were used to detect a transient anomaly of shear wave velocity in the fault zone a ten of hours after the Mw 4.1 foreshock. The purpose of this study is to investigate whether stress parameters had concomitantly temporal or spatial variations. Brune stress drop was computed in a EGF-approach and apparent stress was derived from energy of seismograms. Estimates of individual stations and individual events showed large fluctuations, mostly due to rupture directivity and site effects. A procedure was adopted to decrease the estimate uncertainty obtaining a 39% of the total variance reduction. Brune stress drop and apparent stress showed similar trends implyingstable values of radiation efficiency around 0.23, which is the value expected for self- similarruptures. No evident temporal change emerges from the analyzed stress parameters of repeaters. In contrast, the spatial pattern of Brune stress drop shows a correlation with the b-value obtained by Sugan et al., 2014 that evidenced an asperity characterized by a low b-value on and around the nucleation zone of the mainshock.54 65