Three-dimensional modeling of the behavior of the oblique convergent boundary of southeast Taiwan: Friction and strain partitioning
Journal
Tectonophysics
Journal Volume
333
Journal Issue
1-2
Pages
261-276
Date Issued
2001
Author(s)
Abstract
The Longitudinal Valley Fault (LVF) of eastern Taiwan is the plate boundary between the Philippine Sea plate and Eurasian plate. Analyses of triangulation networks showed that two distinct deformation zones coexist: thrusting prevails between the Pinanshan Conglomerate massif and the Central Range to the west, while strike-slip dominates between the Pinanshan massif and the Coastal Range to the east. Crustal deformation and displacement partitioning along this oblique convergence boundary is investigated by using a 3D distinct-element model. To constrain our models, we take into account the present-day deformation of southern LVF based on geodetic data. Particular attention is paid to the role of the major faults that play an important role in the distribution of the regional strain patterns. The overall deformation is examined by separating the transverse and lateral components of the regional deformation. Our models predict that both the dip-slip and strike-slip increase as the friction coefficient decreases in the eastern fault between Coastal Range and Pinanshan Conglomerate massif. For the western fault between Central Range and Pinanshan Conglomerate massif, the dip-slip increases when the friction coefficient decreases. Conversely the strike-slip decreases as the friction coefficient decreases. The model that provides the best fit in the eastern fault has an effective coefficient in the range of 0.1-0.4. The friction coefficient of 0.27 predicts a strike-slip slip of 20.5 mm/yr, similar to the rate of 22 mm/yr towards N353°E calculated from geodetic data. Along the western fault, the models that provide the best fit have a friction coefficient of 0.8-1.0. These models predict the average fault-normal shortening of about 15.7 mm/yr. The displacement mentioned above is a 30% larger than that of geodetic measurements. Internal deformation by numerous minor faults inside the Pinanshan Conglomerate massif accounts for the discrepancy between the model-predicted and the observed displacement rate. Our models predict an average displacement rate of about 33 mm/yr towards N318°E for reasonable values of the coefficient of friction. These results are consistent with the displacement rate of 28 ±- 8 mm/yr towards N329 ±- 10°E between the Coastal Range and the Central Range based on the trilateration networks around the southern Longitudinal Valley. The friction parameters do affect the orientation and magnitude of slip along faults by a series of parametric studies. We conclude that the strain partitioning of crustal deformation of southern LVF strongly depends on the orientation of oblique convergence, the geometry of faults, and their friction coefficients. Taking into account both the simplified assumptions of the 3D numerical simulation and the uncertainties of geodetic measurements, our estimates of friction parameters along major discontinuities are only valid to first order. © 2001 Elsevier Science B.V. All. rights reserved.
SDGs
Type
journal article