HR: 1340h
AN: T13A-1351    [Abstracts]
TI: Frictional heterogeneity and heat flow
AU: * d'Alessio, M A
EM: dalessio@seismo.berkeley.edu
AF: U.S. Geological Survey, 345 Middlefield Road, MS 977, Menlo Parks, CA 94025 United States
AU: B\"urgmann, R
EM: burgmann@seismo.berkeley.edu
AF: Univ. of California, Berkeley, Dept. Earth & Planetary Science 307 McCone Hall, Berkeley, CA 94720-4767 United States
AU: Williams, C F
EM: colin@usgs.gov
AF: U.S. Geological Survey, 345 Middlefield Road, MS 977, Menlo Parks, CA 94025 United States
AB: The magnitude of frictionally generated heat varies as a function of the frictional strength of a fault. The heterogeneity of natural faults suggests that realistic models of frictional heat generation should consider variations in frictional strength. Here we use numerical models to explore the effects of faults with spatially and temporally heterogeneous frictional strength on the spatial distribution of surface heat flow. Lateral variations of friction along strike combined with the lateral displacement of the blocks by a strike-slip fault requires a non-linear solution to heat flow equations and can produce heat flow patterns that are asymmetric across the fault and along-strike. This asymmetry has implications for conclusions about fault strength drawn from existing heat flow measurements. We explore a range of slip rate-asperity size combinations to determine the limit in which a heterogeneous fault is indistinguishable from a fault with uniform frictional properties. We then compare predictions from models with available heat flow data in the vicinity of the SAFOD drill site and surrounding areas near the creeping section of the San Andreas fault. Because the creeping section does not produce large earthquakes, it is insensitive to frictional weakness caused by dynamic mechanisms. We can directly test the importance of dynamic weakening by treating the section as a frictional heterogeneity.
DE: 8010 Fractures and faults
DE: 8020 Mechanics
DE: 5418 Heat flow
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting