HR: 1340h
AN: T53B-0502    [Abstracts]
TI: Preliminary results from the CAT/SCAN seismic experiment: Structure and kinematics in a slab-rollback setting
AU: * Lerner-Lam, A
EM: lerner@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory of Columbia University, 61 Rt. 9W, Palisades, NY 10964 United States
AB: The Calabrian-Apennine-Tyrrhenian/Subduction-Collision-Accretion Network (CAT/SCAN) is a multi-disciplinary study of the Calabrian Arc in both its subduction-rollback and collisional settings. In the first phase of this international experiment, we have deployed 39 broad-band seismometers in a two-dimensional array extending from the southern Apennines into Calabria. 12 ocean bottom seismometers will extend the coverage into the Ionian and Tyrrhenian seas with two cross-strike profiles, after early Fall 2004. The data from these and other stations in southern Italy are combined with pre-existing data to constrain velocity structure and local earthquake sources. Results provide new information on crustal thickness across the transitions between subduction and collision and on the morphology of the shallow part of the slab near this transition. Precise locations and focal mechanisms illuminate active structure in the crust and within the slab. These results help to address critical questions: (1) what happens to the slab and the overriding plate as they are forced by rollback into the narrowing space between Adria and North Africa? (2) What are the location and nature of the transition between the seismically active thrust belt north of Sicily and the normal faulting along the Apennines and Calabria? (3) Is rollback still in process, or has it stopped? (4) What are the relationships between crust and mantle seismicity and the fine-scale structure of the upper mantle? And (5) what is the relationship between destructive shallow earthquakes in southern Italy and the large-scale dynamics of the slab? We will use travel-time and body-waveform tomography as a proxy for temperature variations related to lithospheric involvement in the subduction and crustal extension, shear-wave splitting as a proxy for vertically integrated mantle deformation and flow pattern, regional surface wave inversions for crustal and upper-mantle azimuth-dependent velocities to provide constraints on the depth distribution of anisotropy related to mantle deformation, and receiver functions to determine crustal structure. Preliminary results of this ongoing experiment will be shown.
DE: 7218 Lithosphere and upper mantle
DE: 8102 Continental contractional orogenic belts
DE: 8123 Dynamics, seismotectonics
DE: 8158 Plate motions--present and recent (3040)
DE: 7200 SEISMOLOGY
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting