The subduction structure of the Northern Apennines: results from the RETREAT seismic deployment

L. Margheriti, S. Pondrelli, D. Piccinini, N. Piana Agostinetti, L. Giovani, S. Salimbeni, F. Pio Lucente, A. Amato, P. Baccheschi, J. Park


The project Retreating-trench, extension, and accretion tectonics, RETREAT, is a multidisciplinary study of the
Northern Apennines (, funded by the United States National Science Foundation
(NSF) in collaboration with the Italian Istituto Nazionale di Geofisica e Vulcanologia (INGV) and the Grant Agency
of the Czech Academy of Sciences (GAAV). The main goal of RETREAT is to develop a self-consistent dynamic
model of syn-convergent extension, using the Northern Apennines as a natural laboratory. In the context of this project
a passive seismological experiment was deployed in the fall of 2003 for a period of three years. RETREAT seismologists
aim to develop a comprehensive understanding of the deep structure beneath the Northern Apennines, with
particular attention on inferring likely patterns of mantle flow. Specific objectives of the project are the crustal and
lithospheric thicknesses, the location and geometry of the Adriatic slab, and the distribution of seismic anisotropy
laterally and vertically in the lithosphere and asthenosphere. The project is collecting teleseismic and regional earthquake
data for 3 years. This contribution describes the RETREAT seismic deployment and reports on key results
from the first year of the deployment. We confirm some prior findings regarding the seismic structure of Central Italy,
but our observations also highlight the complexity of the Northern Apennines subduction system.


temporary seismological network;subduction geometry;upper mantle fabric;seismic anisotropy

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Published by INGV, Istituto Nazionale di Geofisica e Vulcanologia - ISSN: 2037-416X