Shallow subsurface structure of the 2009 April 6 M-w 6.3 L'Aquila earthquake surface rupture at Paganica, investigated with ground-penetrating radar
Roberts, Gerald P. and Raithatha, B. and Sileo, G. and Pizzi, A. and Pucci, S. and Faure Walker, J.P. and Wilkinson, M. and McCaffrey, K.J.W. and Phillips, R.J. and Michetti, A.M. and Guerrieri, L. and Blumetti, A.M. and Vittori, E. and Cowie, P.A. and Sammonds, P.R. and Galli, P. and Boncio, P. and Bristow, Charlie S. and Walters, R.J. (2010) Shallow subsurface structure of the 2009 April 6 M-w 6.3 L'Aquila earthquake surface rupture at Paganica, investigated with ground-penetrating radar. Geophysical Journal International 183 (2), pp. 774-790. ISSN 0956-540X.
P>The shallow subsurface structure of the 2009 April 6 M-w 6.3 L'Aquila earthquake surface rupture at Paganica has been investigated with ground penetrating radar to study how the surface rupture relates spatially to previous surface displacements during the Holocene and Pleistocene. The discontinuous surface rupture stepped between en-echelon/parallel faults within the overall fault zone that show clear Holocene/Pleistocene offsets in the top 10 m of the subsurface. Some portions of the fault zone that show clear Holocene offsets were not ruptured in 2009, having been bypassed as the rupture stepped across a relay zone onto a fault across strike. The slip vectors, defined by opening directions across surface cracks, indicate dip-slip normal movement, whose azimuth remained constant between 210 degrees and 228 degrees across the zone where the rupture stepped between faults. We interpret maximum vertical offsets of the base of the Holocene summed across strike to be 4.5 m, which if averaged over 15 kyr, gives a maximum throw-rate of 0.23-0.30 mm yr-1, consistent with throw-rates implied by vertical offsets of a layer whose age we assume to be similar to 33 ka. This compares with published values of 0.4 mm yr-1 for a minimum slip rate implied by offsets of Middle Pleistocene tephras, and 0.24 mm yr-1 since 24.8 kyr from palaeoseismology. The Paganica Fault, although clearly an important active structure, is not slipping fast enough to accommodate all of the 3-5 mm yr-1 of extension across this sector of the Apennines; other neighbouring range-bounding active normal faults also have a role to play in the seismic hazard.
|Keyword(s) / Subject(s):||Ground penetrating radar, palaeoseismology, seismicity and tectonics, continental tectonics: extensional|
|School:||Birkbeck Schools and Departments > School of Science > Earth and Planetary Sciences|
|Date Deposited:||16 Jun 2011 13:05|
|Last Modified:||30 Aug 2013 15:54|
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