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Calderoni, Giovanna
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Preferred name
Calderoni, Giovanna
Email
giovanna.calderoni@ingv.it
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staff
ORCID
Scopus Author ID
12040362800
Researcher ID
L-6211-2015
35 results
Now showing 1 - 10 of 35
- 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 - 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 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 - PublicationOpen AccessMultidisciplinary investigations using historical data, specific experimental surveys, numerical simulations and earthquake data to assess seismic hazard in a densely urbanized city: the study case of Palermo(2005-11-01)
; ; ; ; ; ; ; ; ; ;Cara, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Cultrera, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Azzara, R. M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Calderoni, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;De Rubeis, V.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Di Giulio, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Giammarinaro, M. S.; Dipartimento di Geologia e Geodesia, Università di Palermo ;Vannoli, P.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Rovelli, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; ; ; ; ; ; ; The city of Palermo (southern Italy) was severely damaged in the past by moderate-magnitude earthquakes located tens of kilometres offshore. The historical monumental heritage and the high density of population motivated large efforts for the seismic risk assessment. We present the geological and seismological studies performed in downtown Palermo as a study case to show how the complexity of an urban environment can be approached with multidisciplinary investigations. Downtown Palermo is characterized by sea deposits in the coastal zone and the alluvial deposits of two rivers (Papireto and Kemonia) of about 150 m width, which were buried and filled during the XVII century. The difficulty of surface geological surveys was compensated through an analysis of aerial photos and more than 2000 borehole data organized in the City-GIS of the Department of Geology and Geodesy of the University of Palermo. A previous study on the well-documented historical damage indicated the major role played by the two river valleys and the sea deposits in controlling the damage distribution, above the assumption of a fairly homogeneous vulnerability of the existing buildings in downtown. To test the feasibility of using ambient noise for recognizing the presence of alluvial deposits in a densely urbanized environment, a large microtremor measurement campaign was performed in Palermo across several profiles. The frequency peaks inferred from the horizontal-to-vertical spectral ratio were compared with numerical simulations to assess the seismic velocity profile and the soil stratigraphy. Moreover, noise data were analyzed through a statistical approach to establish a possible correlation between damage, resonance frequency and amplitude, and geology. After the moderate earthquake of September 6, 2002 (Mw=5.9, 50 km far away), the analysis of the aftershock sequence provided a well documented estimate of the variation of ground motion within the city in the case of linear soil response. Using these aftershocks we computed also synthetic accelerograms of the main shock through Empirical Green’s Functions that provided ground accelerations as large as 50 gals, consistently with the documented EMS-98 intensity. Synthetic accelerograms showed a large variability of horizontal ground motion within the city (a factor of 3 – 4) that confirms the role of local geology in causing an increase of the seismic hazard on sea and alluvial deposits. Finally, we discuss the comparison between the acceleration response spectra calculated for different soil categories and the design elastic spectra provided by EC8.190 167 - PublicationOpen AccessSource Parameters and Radiation Efficiency in the nucleation volume of the Mw 6.1 L’Aquila Earthquake(2018-12)
; ; ; ; ; We analyze Brune stress drop and apparent stress of 25 earthquakes, mainshock, foreshocks and aftershocks, occurring in a 2.5 x 2.5 x 2.5 km 3 volume adjacent to the hypocenter of the destructive Mw 6.1 L’Aquila earthquake. In a previous paper, we used a part of these earthquakes to detect a transient anomaly of shear wave velocity in the fault zone one week before the main shock. The purpose of this study is to enlarge the previous dataset with further close earthquakes (2.2 ≤ Mw ≤ 4.1) to investigate if the same area concomitantly shows temporal and/or spatial variations in the stress parameters. Brune stress drops were computed in a conventional EGF-deconvolution approach using local seismological stations, the resulting values vary in the range 0.2 < Δσ < 8.4 MPa. Apparent stress was derived from the waveform energy corrected for propagation and site effects, it varies in the range 0.03 < a < 1.10 MPa. The ratio η sw = a / Δσ, which provides the radiation efficiency, for the largest part of the investigated earthquakes yields values close to 0.12, which is a value lower than expected for self-similar ruptures. An exception was the immediately following foreshocks and aftershocks (since a four hours before up to a four hours after the main shock, respectively) that result in values of η sw as smaller as 0.06, consistent with ruptures in seismogenic zones with high dynamic strength. The largest Δσ of these events indicates that the temporal variation is associated to a spatial variation due to the main shock asperity rupture, and a satisfactory consistency is found between the smallest and largest Δσ with the largest and smallest b-values, respectively, imaged by other authors in the nucleation volume.44 7 - PublicationRestrictedReport on broad-band stations on topography in Italy(2012-01-24)
; ; ; ; ; ;Pischiutta, Marta; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Vannoli, Paola; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Calderoni, Giovanna; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Pessina, Vera; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Milano-Pavia, Milano, Italia ;Rovelli, Antonio; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; ; ; In Italy, a large part of the national territory is affected by significant topographic variations (grey scale variations of Fig.1). Inevitably, many stations of the Italian Seismic Network (a total of more than 250 broad-band seismological stations) are installed on topographic irregularities. The frequent seismicity of Italy (Fig. 1) produces a useful data set for a comparative study of effects caused by typical topographic shapes (e.g. ridges and cliffs). This report illustrates criteria adopted for the station selection and methods to be used in NERA for the characterization of station topography and site amplification.266 58 - PublicationOpen AccessStrike-Slip Earthquakes at the Northern Edge of the Calabrian Arc Subduction Zone(2021)
; ; ; ; ; ; ;We analyzed earthquakes of a swarm started in October 2019 in the Tyrrhenian Sea, at the northern border of the Calabrian arc subduction zone. The swarm is located in the same area where a subduction-transform edge propagator (STEP) shear- zone -oriented east–west is recognized from ocean floor morphology and submarine volcanoes. We computed focal mechanism, relative location, stress drop, corner frequency, and source directivity of the mainshock Mw 4.4 and of some aftershocks in the local magnitude range 2.3–3.7. Results indicate clearly that the mainshock occurred on a northwest– southeast-oriented fault, with right-lateral strike-slip motion, and it was characterized by a strong directivity of the rupture propagation from northwest to southeast. On the contrary, most of aftershocks were located on another strike-slip fault oriented north- east–southwest and had left-lateral kinematics. The kinematic features of these earth- quakes indicate a strain field with the P-axis oriented north–south and the T-axis oriented east–west. Fault directions and stress field are in good agreement with the theoretical fracture model of shear zones associated with a STEP.162 9