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Di Giovambattista, Rita
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Di Giovambattista, Rita
Email
rita.digiovambattista@ingv.it
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staff
ORCID
Scopus Author ID
6603807120
Researcher ID
L-5747-2015
60 results
Now showing 1 - 10 of 60
- PublicationOpen AccessTransient anomaly in fault-zone trapped waves during the preparatory phase of the 6 April 2009, Mw 6.3 L’Aquila earthquake(2015)
; ; ; ;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; ; Fault-zone trapped waves generated by repeating earthquakes of the 2009 L’Aquila seismic sequence show a sudden, up to 100% increase of spectral amplitudes seven days before the mainshock. The jump occurs ten to twenty hours after the ML 4.1, 30 March 2009 largest foreshock. The amplitude increase is accompanied by a loss of waveform coherence in the fault-trapped wavetrain. Other geophysical and seismological parameters are known to have shown a sudden change after the 30 March foreshock. The concomitance of a consistent change in the fault-zone trapped waves leads us to interpret our observation as due to a sudden temporal variation of the velocity contrast between the fault damage zone and hosting rocks in the focal volume. Fault-zone trapped waves thus provide a refined time resolution for changes occurring near the rupture nucleation, with the indication of a strong variation in one day.214 328 - PublicationOpen AccessIonospheric anomalies detected by ionosonde and possibly related to crustal earthquakes in Greece(2018)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; Ionosonde data and crustal earthquakes with magnitude M > 6:0 observed in Greece during the 2003–2015 period were examined to check if the relationships obtained earlier between precursory ionospheric anomalies and earthquakes in Japan and central Italy are also valid for Greek earthquakes. The ionospheric anomalies are identified on the observed variations of the sporadic E-layer parameters (h0Es, foEs) and foF2 at the ionospheric station of Athens. The corresponding empirical relationships between the seismoionospheric disturbances and the earthquake magnitude and the epicentral distance are obtained and found to be similar to those previously published for other case studies. The large lead times found for the ionospheric anomalies occurrence may confirm a rather long earthquake preparation period. The possibility of using the relationships obtained for earthquake prediction is finally discussed.1125 164 - PublicationOpen AccessSeismic constraints on the present-day kinematics of the Gargano foreland, Italy, at the transition zone between the southern and northern Apennine belts(2005)
; ; ; ;Milano, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Di Giovambattista, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Ventura, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; ; The 1995–2004 seismicity in the Gargano Promontory (hereafter GP) foreland at the transition zone between Southern and Northern Apennine belts (Italy) is analyzed with the aim to put constraints on the present-day kinematics of this key-area of the foreland. The spatial distribution of earthquakes and 54 calculated focal mechanisms show that that the main GP ruptures develop along E-W striking, right-lateral strike-slip faults and NW- SE, normal to left-lateral second-order faults that move in response to a prevailing NW-SE compression (i.e. NE-SW extension). Tacking into account the depth of the relocated seismicity and the available geological information, we propose that the GP shear zone represents an E-W striking, major crustal discontinuity separating sectors of the foreland that move in response to the higher, northeastward propagation velocity of the thrust front of the Northern Apennines with respect to that of the Southern Apennines.164 235 - PublicationRestrictedAccelerating moment release revisited: Examples of application to Italian seismic sequences(2015-01-12)
; ; ; ;De Santis, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Cianchini, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Di Giovambattista, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; ; From simple considerations we propose a revision of the AcceleratingMoment Release (AMR) methodology for improving our knowledge of seismic sequences and then, hopefully in a close future, to reach the capability of predicting the main-shock location and occurrence with sufficient accuracy. The proposed revision is based on the introduction of a “reduced” Benioff strain for the earthquakes of the seismic sequence where, for the same magnitude and after a certain distance from the main-shock epicentre, the closer the events the more they are weighted. In addition,we retain the usual expressions proposed by the ordinary AMRmethod for the estimation of the corresponding main-shock magnitude, although this parameter is the weakest of the analysis. Then, we apply the revised method to four case studies in Italy, three of which are the most recent seismic sequences of the last 9 years culminating with a shallow main-shock, and one is instead a 1995–1996 swarm with no significant main-shock. The application of the R-AMRmethodology provides the best results in detecting the precursory seismic acceleration,when comparedwith those found by ordinaryAMR technique.We verify also the stability of the results in space, applying the analysis to real data with moving circles in a large area around each mainshock epicentre, and the efficiency of the revised technique in time, comparing the results with those obtained when applying the same analysis to simulated seismic sequences.401 46 - PublicationRestrictedSeismicity patterns before the M=5.8 2002, Palermo (Italy)earthquake: seismic quiescence and accelerating seismicity(2004)
; ; ;Di Giovambattista, R.; a Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, 00143 Rome, Italy ;Tyupkin, Yu. S.; Geophysical Center, RAS, Molodezhnaya 3, 117296 Moscow, Russian Federation; Seismic quiescence and accelerating seismic energy release are considered as possible spatio-temporal patterns of the preparation process of the 6 September 2002 Palermo, Italy, earthquake (M 5.8). The detailed properties of the quiescence are analyzed applying the RTL algorithm. The RTL algorithm is based on the analysis of the RTL prognostic parameter, which is designed in such a way that it has a negative value if, in comparison with long-term background, there is a deficiency of events in the time–space vicinity of the tested point. The RTL parameter increases if activation of seismicity takes place. The RTL algorithm identified that a seismic quiescence started from the beginning of November 2001 and reached its minimum at the end of May 2002. The Palermo 2002 earthquake occurred 2 months after the RTL parameter restored its long-term background level. The application of a log-periodic time-to-failure model gives a ‘‘predicted’’ (in retrospect) magnitude M= 6.2 main shock on 5 May 2002.132 24 - PublicationOpen AccessStress drop, apparent stress, and radiation efficiency of clustered earthquakes in the nucleation volume of the April 6, 2009, M w 6.1 L’Aquila earthquake(2019)
; ; ; ; ; We investigate the variability of Brune stress drop (∆σ) and apparent stress (τ a ) of 23 earthquakes occurred in a small crustal volume adjacent to the hypocenter of the destructive M w 6.1 L’Aquila earthquake. Their magnitude range is 2.7 ≤ M w ≤ 4.1. Inter- event variability of stress drop and apparent stress results in a factor of ten, well beyond the individual-event uncertainty. Radiation efficiency η sw = τ a /∆σ varies mostly between 0.1 and 0.2 but, in the days immediately before and after the main shock, η sw tends to be smaller decreasing to values as low as 0.06. This may be the consequence of ruptures migrating in those days into a focal volume with higher dynamic strength. The temporal change of η sw is tentatively interpreted as a spatial variation due to the earthquake migration into the locked portion of the fault that originated the main shock. Consistently, no variation in stress drop and apparent stress is observed between foreshocks and aftershocks but the smallest and largest ∆σ result in a good correlation with the largest and smallest b-values, respectively, imaged by other authors in the rupture nucleation volume.138 63 - PublicationOpen AccessA seismic quiescence before the 2017 Mw 7.3 Sarpol Zahab (Iran) earthquake: Detection and analysis by improved RTL methodA major earthquake, with magnitude Mw 7.3, struck Sarpol Zahab (Kermanshah province, Iran) on November 12, 2017, causing extended damage and casualties. The epicenter was located in the Northwestern part of the Zagros mountain range, an active belt originated by the Arabia-Eurasia collision. We explore seismicity preceding this earthquake, by using the Iranian Seismological Center instrumental earthquake catalog (IGTU), with the aim to identify possible anomalies in background seismicity that can be related with this and other future large events. For this purpose, we used a method for intermediate term forecasts of large earthquakes, namely the Region Time Length (RTL) algorithm, which analyzes declustered catalogs and is sensitive to quiescences that may precede major earthquakes. RTL has been progressively refined and has been applied in several regions worldwide during the last decades. To decluster the earthquake catalog we used a quite novel approach, based on the nearest-neigbour distances between events in the space-time-energy domain, a method that preserves the background seismicity while removing the clustered component. The retrospective application of RTL algorithm to the area surrounding the mainshock epicenter highlights two significant quiescences: one preceding the Sarpol Zahab Mw 7.3 earthquake, and the other occurring before a Mw 5.7 earthquake, which struck the same region on November 2013. The quiescences duration ranges from few months to one year and is compatible with earlier results from different regions of the world. In addition, we applied an enhanced variant of RTL algorithm, which allows us drawing maps for the whole study region and that shows only quiescences consistently detected for different choices of the free parameters, and hence more stable. The resulting map for Northwestern Iran, calculated for the time span 1 June 2017–11 November 2017, evidences two broad quiescence regions, oriented NW-SE along the Zagros belt. One, located to the north, evidences a significant seismic anomaly corresponding to the Sarpol Zahab earthquake, which disappeares immediately after the event. The second one, located in the southeastern part of the study region, persists up to the end of the available catalog (October 4, 2018).
65 97 - ProductOpen AccessLe domande più frequenti sui terremoti(1997-10)
; ; ;Lanza, T.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione AC, Roma, Italia ;Di Giovambattista, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia; Le domande più frequenti sui terremoti messe in rete in occasione del Terremoto di Colfiorito sulla base dei mail degli utenti che arrivavano sul sito web dell'ING202 1047 - PublicationOpen AccessNormal faults and thrusts re-activated by deep fluids: the 6 April 2009 Mw 6.3 L’Aquila earthquake, central Italy.(2010)
; ; ; ; ; ;Di Luccio, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Ventura, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Di Giovambattista, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Piscini, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Cinti, F. R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; ; ; On April 6 2009, a Mw=6.3 earthquake occurred in the central Apennines (Italy) damaging L’Aquila city and the surrounding country. We relocate the October 2008-April 6 2009 foreshocks and about 2000 aftershocks occurred between April 6 and April 30 2009, by applying a double-difference technique and determine the stress field from focal mechanisms. The events concentrate in the upper 15 km of the crust. Three main NW-SE to NNW-SSE striking, 30°-45° and 80°-90° dipping faults activate during the seismic sequence. Among these, a normal fault and a thrust were re-activated with dip-slip movements in response to NE-SW extension. The structural maturity of the seismogenic fault system is lower than that displayed by other systems in southern Apennines, because of the lower strain rate of the central sector of the chain with respect to the southern one. VP/VS increases progressively from October 2008 to the April 6 2009 mainshock occurrence along a NW-SE strike due to an increment in pore fluid pressure along the fault planes. Pore pressure diffusion controls the space-time evolution of aftershocks. A hydraulic diffusivity of 80 m2/s and a seismogenic permeability of about 10-12 m2 suggest the involvement of gas-rich (CO2) fluids within a highly fractured medium. Suprahydrostatic, high fluid pressure (about 200 MPa at 10 km of depth) within overpressurized traps, bounded by pre-existing structural and/or lithological discontinuities at the lower-upper crust boundary, are required to activate the April 2009 sequence. Traps are the storage zone of CO2-rich fluids uprising from the underlying, about 20 km deep, metasomatized mantle wedge. These traps easily occur in extensional regimes like in the axial sector of Apennines, but are difficult to form in strike-slip regimes, where sub-vertical faults may cross the entire crust. In the Apennines, fluids may activate faults responsible for earthquakes up to Mw=5-6. Deep fluids more than tectonic stress may control the seismotectogenesis of accretionary wedges.459 562 - PublicationOpen AccessA seismic sequence from Northern Apennines (Italy) provides new insight on the role of fluids in the active tectonics of accretionary wedges(2009-04)
; ; ; ; ;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 ;Burrato, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Ventura, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; ; We analyze a seismic sequence which occurred in 2000 along the Northern Apennines accretionary wedge (Italy). The sequence developed within the Cretaceous–Triassic limestones of the tectonic wedge, where methane-rich and oil reservoirs are stored. Ruptures mainly developed on WNW–ESE striking thrusts. The compressive stress field is consistent with that acting at regional scale in Northern Apennines. Seismic parameters indicate that fluids are involved in the seismogenic process. The amplitudes of the P and S phases and data from some stations evidence a P to S conversion within Vp/Vs=2.1 layer. The attenuation properties of crust show a higher attenuation zone located west of the epicentral cloud. Eight hundred aftershocks delineate a sub-vertical cloud of events between 7 and 14 km depth. The space–time evolution of the aftershocks is consistent with a diffusive spreading (diffusivity=1.9 m2/s) along vertically superimposed thrusts. Diffusion also controls the time evolution of the sequence. Fluid pressure is estimated to be roughly equal to the vertical, lithostatic stress. The overpressure within reservoirs develops by tectonic compaction processes. The fluids upraise along sub-vertical fractures related to the shortening of the wedge. The 2000 sequence occurred in an area that separates a thermal and deeper petroleum system from a shallower biogenic system. The divider of these systems controls the attenuation properties of the crust. The fluid–rock interaction at seismogenetic depth is related to hydrothermal processes more than to compaction. In accretionary wedges, seismicity activating superimposed thrusts may drive methane and oil upraising from the upper crust.309 1261