2012 IRIS Workshop

A View of the Taiwan Orogeny from Joint Receiver Functions, Local Seismicity, and Tomography

Vera Schulte-Pelkum: University of Colorado; Hao Kuo-Chen: SUNY Binghamton, Francis Wu: SUNY Binghamton

Receiver functions common point conversion stack (from broadband stations shown as white triangles) overlaid with local event tomographic compressional velocity contour lines (from stations shown as green triangles), taken across southern Taiwan on the black line shown in the inset topographic map. Moho (complex appearance due to azimuthal variations in the receiver functions) and slab subducting to the East are visible.

Full-resolution graphics file in original format: 0067.png

Taiwan is the site of a young, active continent-arc collision with ongoing mountain building and a complicated geometry, with the Eurasian plate subducting eastwards in the south of the island and the Philippine plate subducting northwards under the northern part of the island. The National Science Foundation-funded TAIGER project (co-sponsored in Taiwan by National Science Council and other agencies) seeks to decipher the tectonic processes operating in the collision. We use newly determined crustal velocity models (Hao et al., 2012) to construct a receiver function image of the orogen, targeting the Moho and the Eurasian slab geometry. The apparent discontinuous Moho structure is due to significant azimuthal variability in the receiver functions, and we investigate dipping structures and crustal anisotropy using radial and tangential receiver functions. We map S-P delay times from receiver functions (mode converted teleseismic phases) relative to S-P arrival times from local seismicity. Such mapping in delay time space removes the distortion introduced by unresolved velocity structure that can bias event depths and time-to depth mapping of receiver functions, and thus allows for accuracy when conducting hypothesis tests for proposed thin- versus thick-skinned deformation models and locating seismogenic structures by placing seismicity in spatial context with crustal structure with high resolution.

Acknoweldgements: This study was funded by NSF grant EAR-0409266.

Keywords: receiver_function, anisotropy, subduction, continental_collision, seismicity

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