Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/8198
AuthorsMalagnini, L.* 
Lucente, F.* 
De Gori, P.* 
Akinci, A.* 
Munafò, I.* 
TitleControl of pore fluid pressure diffusion on fault failure mode:Insights from the 2009 L’Aquila seismic sequence
Issue Date2012
Series/Report no./117(2012)
DOI10.1029/2011JB008911
URIhttp://hdl.handle.net/2122/8198
Keywords2009 La'Aquila sequence
pore fluid pressure diffusion
seismic hazard
Subject Classification04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous 
AbstractThe MW 6.13 L’Aquila earthquake ruptured the Paganica fault on 2009/04/06 at 01:32 UTC, and started a strong sequence of aftershocks. For the first four days, the region north of the hypocenter of the main quake was shaken by three large events (MW 5.0) that ruptured different patches of the Monti della Laga fault (hereafter “Campotosto”). In our hypothesis, these aftershocks were induced by a dramatic reduction in the fault’s shear strength due to a pulse of pore fluid pressure released after the L’Aquila main earthquake. Here we model the time evolution of the pore fluid pressure northward from the main hypocenter. We show that, during the sequence, the Campotosto fault failed in multiple episodes, when the specific patches/asperities underwent fluid pressure-related strength reductions of 7–10 MPa. Although such drops in strength are very large in amplitude, the contribution of other weakening mechanisms (perturbations of the Coulomb shear stress, and/or dynamic stresses induced by passing seismic waves) cannot be ruled out by our observations. However, the Coulomb shear stress variations either had negative amplitudes down to 0.2 MPa (i.e., tended to inhibit further seismic activity), or had very small positive amplitudes (<0.05 MPa). Paleoseismological evidence supports the hypothesis that larger events (MW 6.5–7) have occurred on the Paganica fault [EMERGEO Working Group, 2009], whereas Lucente et al. [2010] concluded that an important migration of pore fluids characterized the preparatory phase of the L’Aquila main shock. Consequently, the MW 6.13 L’Aquila earthquake may be analogous, at a larger scale, to one of the three Campotosto largest aftershocks. The complex behavior observed for the L’Aquila-Campotosto fault system seems to be common to other seismogenic structures in the Central Apennines (e.g., the Umbria-Marche fault system), and need to be taken into consideration for the assessment of seismic hazard.
Appears in Collections:Papers Published / Papers in press

Files in This Item:
File Description SizeFormat 
Malagnini_etal_JGR_2012.pdf4.27 MBAdobe PDFView/Open    Request a copy
Show full item record

Page view(s)

104
checked on Apr 28, 2017

Download(s)

29
checked on Apr 28, 2017

Google ScholarTM

Check

Altmetric