|TAIGER (TAiwan Integrated GEodynamics Research) project for testing models of Taiwan orogeny.|
Crustal Images (Seismic and magnetotelluric)
On the upper left are tomographic sections (absolute velocity and perturbation from initial model) using CWB short period network data and on the bottom right is a MT profile along the southern line in the location inset. The white dots in the tomographic images are seismicity after the 1999 Chi-Chi earthquake. Notice the steeply west-(to the left) dipping zone at the depths between about 15 and 35 km. Focal mechanisms in the zone show a steep west-dipping plane with the Central Range side down and the Foothill side up. It is a boundary separating the high and low velocity zones in the lower crust. The zone underlies the Lishan Fault.
On the bottom right is a combined TE/TM/HZ inversion of resistivity image MT (Bertrand and Unsworth, personal communication 2007). The most prominent feature is a major conductor surfacing at the trace of the Lishan Fault, which coincides with the Lushan Hot Springs on the 200 Line. This conductor may be due to aqueous fluids and/or partial melt. The depth of this conductor is significant as it cuts across the inferred shallow decollement, which would be evidence against a decollement existing this far East beneath the central ranges. The Central Range is a relatively resistive zone.
At the shallow level in the Coastal Plain area the two images show the presence of low velocity materials on top.
Wu, F. T.,Lavier, L. UT, and US and Taiwan TAIGER TEAMS (2007) Collision Tectonics of Taiwan and TAIGER Experiments, Eos Trans. AGU, 88(52), Fall Meet. Suppl., Abstract T51A-0321.
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