Seismological evidence for the brittle-ductile interaction hypothesis on earthquake loadingReport as inadecuate

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Earth, Planets and Space

, Volume 56, Issue 8, pp 823–830

First Online: 24 June 2014Received: 28 November 2003Revised: 25 February 2004Accepted: 23 June 2004


We extended the analyses of temporal variation of coda Q and seismicity by Jin and Aki 1989, 1993 for central and southern California to year 2003. We use the relative frequency NMc of earthquakes in a certain magnitude range around Mc characteristic to a seismic region to quantify the seismicity. The cross-correlation function between coda Q and NMc is calculated using a 10-year moving time window. The correlation coefficient for the entire period of about 60 years is peaked at the zero-time shift with the value close to 0.8 for both regions. We found, however, the simultaneous correlation is disturbed before major earthquakes. The disturbance is, consistently, a delay in the change of coda Q relative to that of NMc before the occurrence of a major earthquake. We attribute the temporal change in coda Q to fractures in the ductile part of the lithosphere and that in NMc to the response of the brittle part to the ductile fracture. We believe that Mc characteristic to a seismic region is originated from a characteristic size of fractures in the ductile zone of the lithosphere. The observed delay of coda Q change relative to NMc before a major earthquake can be explained simply by the strain energy stored in the brittle part of lithosphere reaching a saturation limit and starting to flow back to the ductile part.

Key wordsCoda Q characteristic magnitude Mc seismogenic zone plate driving earthquake loading brittle-ductile transition zone  Download to read the full article text

Author: Anshu Jin - Keiiti Aki - Zhen Liu - Vladimir. I. Keilis-Borok


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