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Subscriber Access to Full Article (Nonsubscribers may purchase for $9.00, Includes print PDF, file size: 340387 bytes)
GEOPHYSICAL RESEARCH LETTERS,
VOL. 34,
L04304,
doi:10.1029/2006GL028860,
2007
End of subduction in northern Apennines confirmed by observations of quasi-Love waves from the great 2004 Sumatra-Andaman
earthquake
V. Levin
Department of Geological Sciences, Rutgers University, Piscataway, New Jersey, USA
J. Park
Department of Geology and Geophysics, Yale University, New Haven, Connecticut, USA
F. P. Lucente
Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy
L. Margheriti
Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy
S. Pondrelli
Istituto Nazionale di Geofisica e Vulcanologia, Bologna, Italy
Abstract
Surface waves from the great Sumatra-Andaman earthquakes of 2004 and 2005 that cross Italy south of ∼44°N display Love-to-Rayleigh
scattered waves (quasi-Love phases) diagnostic of sharp lateral gradients in the anisotropic properties of Earth's upper mantle.
Surface waves that traverse Italy further north lack this distinctive phase, documenting a change in the upper mantle fabric
that is corroborated by a shift in the fast polarization of shear wave birefringence. These observations suggest that orogen-parallel
asthenospheric extension behind the retreating Apennines slab has limited geographical expression. We hypothesize that subduction
rollback currently terminates at 44°N, while the upper mantle flow pattern further to the north has been recently rearranged.
Received 29
November
2006;
accepted 10
January
2007;
published 21
February
2007.
Keywords: seismic anisotropy;
rollback;
northern Apennines.
Index Terms: 7255 Seismology: Surface waves and free oscillations; 8120 Tectonophysics: Dynamics of lithosphere and mantle: general (1213); 8170 Tectonophysics: Subduction zone processes (1031, 3060, 3613, 8413).
Subscriber Access to Full Article (Nonsubscribers may purchase for $9.00, Includes print PDF, file size: 340387 bytes)
Citation: Levin, V., J. Park, F. P. Lucente, L. Margheriti, and S. Pondrelli
(2007),
End of subduction in northern Apennines confirmed by observations of quasi-Love waves from the great 2004 Sumatra-Andaman
earthquake,
Geophys. Res. Lett.,
34,
L04304,
doi:10.1029/2006GL028860.
Copyright 2007 by the American Geophysical Union.
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