HR: 1340h
AN: T33C-0578    [Abstracts]
TI: Results from CAT/SCAN, the Calabria-Apennine-Tyrrhenian/Subduction-Accretion-Collision Network
AU: * Steckler, M S
EM: steckler@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964 United States
AU: Amato, A
T33C-0578 AF: Istituto Nazionale di Geofisica e Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata, Roma, 00143 Italy
AU: Guerra, I
T33C-0578 AF: Dipartimento di Fisica, Universita della Calabria, Cosenza, 87040 Italy
AU: Armbruster, J
T33C-0578 AF: Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964 United States
AU: Baccheschi, P
T33C-0578 AF: Istituto Nazionale di Geofisica e Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata, Roma, 00143 Italy
AU: DiLuccio, F
EM: steckler@ldeo.columbia.edu
AF: Istituto Nazionale di Geofisica e Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata, Roma, 00143 Italy
AU: Gervasi, A
T33C-0578 AF: Dipartimento di Fisica, Universita della Calabria, Cosenza, 87040 Italy
AU: Harabaglia, P
T33C-0578 AF: Centro di Geodinamica, Universit… della Basilicata, Potenza, 85100 Italy
AU: Kim, W
T33C-0578 AF: Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964 United States
AU: Lerner-Lam, A
T33C-0578 AF: Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964 United States
AU: Margheriti, L
T33C-0578 AF: Istituto Nazionale di Geofisica e Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata, Roma, 00143 Italy
AU: Seeber, L
T33C-0578 AF: Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964 United States
AU: Tolstoy, M
T33C-0578 AF: Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964 United States
AU: Wilson, C K
T33C-0578 AF: Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964 United States
AB: The Calabrian Arc region is the final remnant of a Western Mediterranean microplate driven by rollback. Calabria itself is an exotic block that rifted off Sardinia and opened the Tyrrhenian Sea back-arc basin in its wake. The Calabrian Arc rapidly advanced to the southeast, with subduction ahead and extension behind, following subduction rollback of the Mesozoic seafloor. The subduction zone meanwhile collided progressively with the Apulia to form the Apennines in peninsular Italy and with the Africa to form the Maghrebides in Sicily. The Calabrian Arc is where the transition from subduction to continental collision is occurring. The collisions on either side of Calabria have restricted oceanic subduction to a narrow 200-km salient with well-defined edges and seismicity that extends to over 500 km depth. The collisions have also slowed, or possibly even halted, the rapid advance of the arc. Whether rollback of the oceanic lower plate of the Ionian Sea continues and whether the upper plate of Calabria continues to move as an independent plate are both uncertain. The Calabrian-Apennine-Tyrrhenian/Subduction-Collision-Accretion Network (CAT/SCAN) is a passive experiment to study of the Calabrian Arc and the transition to the southern Apennines. The land deployment consisted of three phases. The initial phase included an array of 39 broadband seismometers onshore, deployed in the winter of 2003/4. In September 2004, the array was reduced to 28 broadband and 8 short-period instruments. In April 2005, the array was reduced once again to 20 broadband and 2 short-period instruments. The field deployment was completed in October 2005. Offshore, 12 broadband Ocean Bottom Seismometers (OBSs) were deployed in the beginning of October 2004. Data from 4 OBSs have been recovered so far with deployment durations from a few weeks to almost one year. Fishing activity has been strongly implicated in the early recoveries, (with one instrument returned by fishermen), and is suspected for the instruments that were not recovered. The experiment is determining the structure of the Calabrian subduction and southern Apennine collision systems and the structure of the transition from oceanic subduction in Calabria to continental collision in the southern Apennines. We have delineated a strong anisotropy with a fast direction following the curved arc, but weaker anisotropy beneath the Tyrrhenian Sea. Receiver function images show variations in crustal thickness throughout the region, consistent with previous conceptual models. We also image a negative polarity interface dipping to the southwest that we interpret as the main thrust ramp in the north transitioning to the subduction interface in the south. The transition from one to the other is marked by a loss of amplitude in the Moho conversion. Local seismicity is consistent with surface structure in showing extension normal and parallel to the Calabrian forearc as well as continuing southeastward motion of Calabria relative to the southern Apennines and Maghrebides.
DE: 3050 Ocean observatories and experiments
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 7240 Subduction zones (1207, 1219, 1240)
DE: 8104 Continental margins: convergent
DE: 9335 Europe
SC: Tectonophysics [T]
MN: Fall Meeting 2005