HR: 17:35h
AN: T14C-07    [Abstracts]
TI: Identifying Blind Seismogenic Faults at the Apennine Thrust Front: Implications for the Seismic Hazard of the Northern Marche (Central Italy) Coastal Belt
AU: * Basili, R
EM: basili_r@ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Sismologia e Tettonofisica, Via di Vigna Murata, 605, Rome, 00143 Italy
AU: Mirabella, F
EM: mirabell@unipg.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Sismologia e Tettonofisica, Via di Vigna Murata, 605, Rome, 00143 Italy
AU: Mirabella, F
EM: mirabell@unipg.it
AF: Dipartimento Scienze della Terra, Universit\'{a} di Perugia, Piazza Universit\'{a} 1, Perugia, 06100 Italy
AU: Vannoli, P
EM: vannoli@ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Sismologia e Tettonofisica, Via di Vigna Murata, 605, Rome, 00143 Italy
AU: Valensise, G
EM: valensise@ingv.it
AF: Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Sismologia e Tettonofisica, Via di Vigna Murata, 605, Rome, 00143 Italy
AB: The structural architecture of the northern Apennines is dominated by NE-verging arc-shaped folds and thrusts that developed through progressive migration of the contractional process combined with regional uplift. Migration and shortening of the Apennine fold-and-thrust system appear to be constant over space (from SW to NE) and time (since the Burdigalian; ca. 19 My), indicating that the two major frontal thrusts are active. The coastal area of the northern Marche - one of the most densely populated regions in central Italy - extends between the axes of these two structures. We reconstructed the deep geometry, size, and style of deformation of these youngest folds and blind thrusts by using seismic reflection lines. Anomalously behaving river courses and warped coastal and fluvial terraces provided insights on the rates of their recent activity. The occurrence of several historical and instrumental earthquakes suggests that these structures can also be seismogenic. The results of a detailed analysis on one of these structures allowed us to constrain the source of the Senigallia, 1930, earthquake (Me 5.9) as a blind thrust fault accompanied by anticlinal growth. Prospectively, our findings can be extended at the entire fault system to (i) outline its possible segmentation, (ii) identify the areas that have been historically silent and that could be regarded as potential seismic gaps, and (iii) evaluate the seismic potential of the region. Successfully addressing the above three points is a necessary step for individual-source, time-dependent seismic hazard assessment.
DE: 7223 Seismic hazard assessment and prediction
DE: 8005 Folds and folding
DE: 8107 Continental neotectonics
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting