Elucidating the geometry of the active Shanchiao Fault in the Taipei metropolis, northern Taiwan, and the reactivation relationship with preexisting orogen structures

Chih Tung Chen, Jian Cheng Lee, Yu Chang Chan, Chia Yu Lu, Louis Suh Yui Teng

研究成果: 雜誌貢獻期刊論文同行評審

12 引文 斯高帕斯(Scopus)

摘要

The Shanchiao Fault is an active normal fault with documented paleoearthquakes in the Taipei metropolis, Taiwan. While posing direct seismic threat on the multimillion population, its crustal-scale fault plane configuration has not been constrained. This study presents the first attempt to resolve the fault plane dip changes of the Shanchiao Fault within the upper crust by forward modeling late Quaternary deformation. Tectonic subsidence over the last ~23 ka is estimated from vertical displacements of a rapidly formed alluvial fan horizon deformed into a dramatic rollover monocline. A 2-D profile across the Shanchiao Fault is chosen for elastic half-space dislocation modeling, and the results suggest that the fault is listric in the shallow crust with an abrupt change from subvertical ramp (85°-75°) to near-horizontal flat (10°-15°) at 3-4 km depth, consistent with an origin from the inversion of an orogen-related thrust detachment. Given the presence of rift-related fabrics in the underthrust Chinese Continental Margin basement beneath the Taiwanese orogenic wedge, listric ramp-flat-ramp models with a second deeper bend to 60° dip are also tested. Reasonable fits with the geological observations are produced when the lower ramp is located at greater than 8 km depth, which correlates with the hypocentral location of a moderate earthquake in 2004. Joint reactivation of preexisting thrust and rift faults by the Shanchiao Fault is therefore plausible with implications for seismic hazard in the Taipei area.

原文???core.languages.en_GB???
頁(從 - 到)2400-2418
頁數19
期刊Tectonics
33
發行號12
DOIs
出版狀態已出版 - 1 12月 2014

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