HR: 08:45h
AN: S41C-04    [Abstracts]
TI: Crustal Thickness Estimates for Tuscany and the Northern Apennines from Surface Wave Dispersion Curves
AU: * Mayeau, T
EM: tara.mayeau@yale.edu
AF: Dept of Geology and Geophysics, Yale Univ 210 Whitney Ave, New Haven, CT 06511, United States
AU: Park, J
EM: jeffrey.park@yale.edu
AF: Dept of Geology and Geophysics, Yale Univ 210 Whitney Ave, New Haven, CT 06511, United States
AU: Levin, V
EM: vlevin@rci.rutgers.edu
AF: Dept of Geological Sciences, Rutgers Univ 610 Taylor Road, Piscataway, NJ 08854, United States
AU: Brandon, M T
EM: mark.brandon@yale.ed
AF: Dept of Geology and Geophysics, Yale Univ 210 Whitney Ave, New Haven, CT 06511, United States
AB: The tectonic processes that define the Northern Apennines and Tuscany are more complicated than a simple subduction model and thus subject to significant controversy. While tomographic images seem to show a descending slab below Northern Italy, a lack of earthquakes below 100 km is inconsistent with ordinary subduction. Some have proposed that subduction may have ceased, and the slab beginning to founder. Another view is that that subduction is not the primary process, but rather the lower lithosphere is detaching to cause the surface deformation that characterizes the Apennines. In the case of subduction, Tuscany should represent the extensional back arc and have thinned crust due to stretching. If delamination has occurred the crust could also be thinned, but by the removal of the lower crust. However, if the crust beneath Tuscany is thick, then some other process must also be at work. Previous active-source and receiver-function studies have found that the crust under Tuscany to be thin (about 20-25 km) while the crust near the crest of the Apennines is believed to be 30-40 km thick. We will report estimates of crustal thickness based on dispersion curves determined for a variety of two-station pairs using wavelet correlation. The stations used were part of the RETREAT deployment, a broadband seismological experiment supported by INGV (Italy), NSF (USA) and the Czech Academy of Sciences. The measured dispersion curves were compared with theoretical dispersion curves for a variety of crustal thicknesses to find a best fit thickness that could serve as a constraint for future crustal studies. In preliminary analyses, dispersion curves measured between stations in the Apennines orogen suggest a thick crust in that region. The dispersion curves for station pairs within Tuscany are less conclusive, but include examples where thin crust can be argued.
DE: 7205 Continental crust (1219)
DE: 7255 Surface waves and free oscillations
DE: 8104 Continental margins: convergent
DE: 8170 Subduction zone processes (1031, 3060, 3613, 8413)
SC: Seismology [S]
MN: 2007 Fall Meeting