Tectonic effect for establishing a semi-dynamic datum in Southwest Taiwan

Kuo-En Ching,Kwo-Hwa Chen

doi:10.1186/s40623-015-0374-0

Kuo-En Ching, Kwo-Hwa Chen

Open Access

https://doi.org/10.1186/s40623-015-0374-0

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Abstract

To accommodate the effects of crustal deformation in the current national static geodetic datum (Taiwan Geodetic Datum 1997 (TWD97)) in SW Taiwan, 221 campaign-mode global positioning system (GPS) stations from 2002 to 2010 were used in this study to generate a surface horizontal velocity model for establishing a semi-dynamic datum in SW Taiwan. An interpolation method, Kriging, and a tectonic block model, DEFNODE, were used to construct the surface horizontal velocity model. Forty-four continuous GPS stations were used to examine the performance of the semi-dynamic datum through exterior validation. The average values of the residual errors obtained using the Kriging method for the north and east components are ±1.9 and ±2.2 mm/year, respectively, whereas those obtained using the block model are ±2.0 and ±2.9 mm/year, respectively. The distribution of residuals greater than 5 mm/year for both models generally corresponds to a high strain rate area derived using the horizontal velocity field. In addition, these residuals may result from deep-seated landslide and active folding or mud diapir in a mudstone area. Similar exterior checking results obtained using the Kriging interpolation method and block model for SW Taiwan indicate a high station density and a relatively satisfactory station spatial coverage. However, the block model is superior to the Kriging method due to the consideration of characteristics of the geological structure in the block model. In addition, result from traditional coordinate transformation was used to compare with the semi-dynamic datum. The results indicate that a semi-dynamic datum is a feasible solution for maintaining the accuracy of TWD97 at an appropriate level over time in Taiwan.

Highlights

Taiwan is located at the present-day plate convergence boundary between the Eurasian plate and the Philippine Sea plate (Fig. 1); earthquake activities are abundant and the convergence rate is approximately 82 mm/year across the island, reflecting a high surface strain rate of up to 1 μstrain/year (Yu et al 1997; Bos et al 2003; Chang et al 2003; Byrne et al 2011)
The purpose of this paper is to provide a horizontal velocity model based on 265 global positioning system (GPS) observations for estimating and predicting the coordinate changes associated with the horizontal crustal motion in SW Taiwan (Fig. 1)
A national geodetic datum is crucial in studying Earth science, establishing basic infrastructure, developing technology, and conducting academic analyses in a country

Summary

Introduction

Taiwan is located at the present-day plate convergence boundary between the Eurasian plate and the Philippine Sea plate (Fig. 1); earthquake activities are abundant and the convergence rate is approximately 82 mm/year across the island, reflecting a high surface strain rate of up to 1 μstrain/year (Yu et al 1997; Bos et al 2003; Chang et al 2003; Byrne et al 2011). Establishing a semi-dynamic datum by assigning deformation models to a specific geodetic datum, such as the Japanese Geodetic Datum 2000 (Tanaka et al, 2007) and the New Zealand Geodetic Datum 2000 (Grant and Blick 1998; Beavan and Haines 2001; Beavan and Blick 2007), is an appropriate means for sustaining the coordinate spatial accuracy for a national-based geodetic datum at the plate boundary to account for the high surface strain.

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