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Stucchi, E. M.
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Stucchi, E. M.
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- PublicationRestrictedSeismological, geological and geophysical constraints for the Gualdo Tadino fault, Umbria–Marche Apennines (central Italy)(2005)
; ; ; ; ; ;Ciaccio, M. G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Barchi, M. R.; Università di Perugia ;Chiarabba, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione CNT, Roma, Italia ;Mirabella, F.; Università di Perugia ;Stucchi, E.; Università di Milano; ; ; ; The April 3, 1998 Mw=5.1 Gualdo Tadino earthquake (central Italy) was the last significant event in the 6-month-long Umbria–Marche seismic crisis. This event and its aftershocks occurred in an area where active faulting produces no striking geological and geomorphological effects. In this study, we investigated the ruptured fault using detailed seismological data and a re-processed and re-interpreted seismic reflection profile. Aftershock location and focal mechanisms were used to constrain the geometry and kinematics of the ruptured fault and a comparison was made with the subsurface image provided by the seismic profile. We found that the 1998 Gualdo Tadino earthquake occurred on a WSW-dipping, normal fault, with a length of about 8 km and a relatively gentle dip (308–408), confined between 3.5 and 7 km in depth. Kinematics of the mainshock and aftershocks revealed a NE-trending extension, in agreement with the regional stress field active in the Northern Apennines belt. The Mw = 5.1 earthquake originated above the top of the basement and ruptured within the sedimentary cover, which consists of an evaporites–carbonates multilayer. We hypothesised that the active fault does not reach the surface (blind normal fault). D 2005 Elsevier B.V. All rights reserved.367 19 - PublicationRestrictedReprocessing of the CROP M12A seismic line focused on shallow-depth geological structures in the northern Tyrrhenian Sea(2011-03)
; ; ; ; ; ;Tognarelli, A.; Consorzio di Geofisica, Università di Pisa, Pisa, Italy ;Stucchi, E. M.; Dipartimento Scienze della Terra, Università di Milano, Milano, Italy ;Musumeci, G.; Dipartimento Scienze della Terra, Università di Pisa, Pisa, Italy ;Mazzarini, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Pisa, Pisa, Italia ;Sani, F.; Dipartimento Scienze della Terra, Università di Firenze, Firenze, Italy; ; ; ; This work deals with the reprocessing of the M12A CROP marine seismic profile, that crosses the northern Tyrrhenian Sea, south of Elba Island. The reprocessing was carried out to improve the visibility and resolution of the structures corresponding to the lower crust (two-way traveltimes lower than 4 s) that are located at depth. In this time window, we apply recently developed methodologies to enhance the signal-to-noise ratio, paying particular attention to the suppression of the short and long period reverberations and to the velocity model building for depth migration. The velocity field used for the depth conversion is iteratively updated by means of the migration velocity analysis on common image gathers. The final products of this work are time and post-stack, depthmigrated sections that can contribute to the understanding of the structural complexity of the investigated area.186 36 - PublicationRestrictedInsights on the seismogenic layer thickness from the upper crust structure of the Umbria-Marche Apennines (Central Italy)(2008)
; ; ; ; ; ;Mirabella, F.; Università di Perugia ;Barchi, M. R.; Università di Perugia ;Lupattelli, A.; Università di perugia ;Stucchi, E.; Università di Milano ;Ciaccio, M. G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; ; ; [1] We reconstruct the subsurface geology in a region of the northern Apennines (central Italy) where a protracted extensional sequence occurred in 1997–1998 with maximum magnitude M = 6.0. Our study is mainly based on the interpretation of three reprocessed seismic reflection profiles crossing the epicentral area, which constrain the subsurface geometry to a depth of about 12 km where most of the shallow seismicity occurs. Comparing the subsurface setting with accurately determined earthquake locations, we find that the seismicity is located entirely within the sedimentary cover and does not penetrate the underlying basement. This is explained by considering that the sedimentary cover is rather thick and composed of relatively strong lithologies (platform carbonates and evaporites), while the upper part of the basement consists of weak phyllites and siliciclastic rocks. This weak horizon is also evidenced by the low-Vp values measured in deep wells of the region. Its effect is to decouple the sedimentary cover from the crystalline basement, where only microseismicity occurs. Our study indicates that local structure and stratigraphy can significantly influence the distribution of seismicity within the upper crust, particularly in complex geological environments such as thrust-and-fold belts.393 40 - PublicationRestrictedCase History Comparison between reprocessed seismic profiles: Seismologic and geologic data — A case study of the Colfiorito earthquake area(2006)
; ; ; ;Stucchi, E.; Università di Milano ;Mirabella, F.; Università di Perugia ;Ciaccio, M. G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; ; Seismic reflection data are used to reconstruct the sub- surface geologic structures below the Umbria-Marche region in Italy, a highly seismogenic area with a recent history of seismic activity (the 1997–1998 Colfiorito sequence). We reprocess three vibroseis seismic profiles (acquired in the early 1980s for hydrocarbon explo- ration) whose stacked sections were optimized for relatively deep oil targets. On the reprocessed seismic profile closest to the epicentral area, we construct the main reflectors to a depth of about 4 s (two-way time) and compare this interpretation with the available hypocenters of the 1997 earthquakes. The improvements in visualizing the shallow and deep reflections provide a better correlation between the re- flectors and the observed surface structures as well as a better delineation of the basement-rock geometry. We find that part of the Colfiorito sequence is localized around some of the reflectors in the reflection profile, which we interpret as related to the active normal faults that outcrop at the surface.226 17