HR: 11:30h
AN: T32C-05 INVITED    [Abstracts]
TI: Strength and Mechanics of the Taiwan Thrust Belt
AU: * Suppe, J
EM: suppe@princeton.edu
AF: Department of Geosciences National Taiwan University, No. 1, Sec. 4 Roosevelt Road, Taipei, 10617, Taiwan
AU: Yue, L
EM: lifanyue@gmail.com
AF: Chevron Energy Technology Company, 14141 Southwest Freeway, Sugar Land, TX 77478, United States
AB: The central Taiwan thrust belt is an important laboratory for study of fault and crustal mechanics because its structure is well constrained and it is the site of the well-instrumented 1999 Chi-Chi earthquake (M_w 7.6) and the post-Chi-Chi TCDP scientific drill holes. Here we summarize recent results on crustal and fault strength within this active thrust belt, based on critical-taper wedge mechanics and published TCDP temperature anomalies and stress measurements. These constraints indicate that the major faults are exceedingly weak with effective friction of σ_τ/ ρ gz ≈ 0.03-0.1, whereas the deforming crust containing them is strong (σ₁-σ₃)/ ρ gz ≈ 0.6-1. Thus there is an order of magnitude difference between fault strength and crustal strength σ_τ/(σ₁-σ₃)≈ 0.1. Furthermore, the extreme fault weakness is not caused by regional ambient high pore-fluid pressures as classically proposed by the Hubbert and Rubey because petroleum bore-hole data show that the fluid pressures are regionally hydrostatic. These results underline the outstanding causal questions of fault weakness and crustal strength.
DE: 8004 Dynamics and mechanics of faulting (8118)
DE: 8045 Role of fluids
DE: 8118 Dynamics and mechanics of faulting (8004)
DE: 8159 Rheology: crust and lithosphere (8031)
DE: 8164 Stresses: crust and lithosphere
SC: Tectonophysics [T]
MN: 2007 Fall Meeting