Abstract
Abstract Malaysia is located at the stable part of the tec-tonic Sundaland platelet in SE Asia. The platelet is surrounded in almost every direction by tectonically active convergent boundaries, at which the Philippine Sea, the Australian and the Indian Plates are subducting respectively from the East, South and West.The current Malaysia geodetic reference frame called MGRF2000 is a static reference frame and hence did not incorporate the effects of plate motion and the ensuing deformation from (megath-rust) earthquakes. To prevent degradation of Continuously Operating Reference Station (CORS) coordinates, a new time-dependent national reference frame was developed. Taking advantage of the availability of the GNSS data of the CORS network in Malaysia, notably the Malaysia Active GPS System (MASS) and Malaysia Real-Time Kinematic GNSS Network (MyRTKnet), a more accurate and robust Malaysian geodetic reference frame was determined, fully aligned and compatible with ITRF2014. The cumulative solution obtained from stacking Malaysian CORS position time series formed the basis of the new MGRF2020 realization. It consists of 100+ station positions at epoch 2020.0, station velocities and Post-Seismic Deformation (PSD) parametric models for stations subjected to major earthquakes. The (1999-2018) position time series exhibit Weighted Mean Root Square (WRMS) values of 3.0, 3.2 and 7.6 mm in respectively the East, North and Vertical components. A new semi-kinematic geodetic datum (GDM2020) for Malaysia, useable for GIS, mapping and cadastre applications is proposed to replace the existing static datum (GDM2000). A transformation suite to convert the spatial databases from GDM2000 to GDM2020 was also developed.
Highlights
The current Malaysia geodetic datum is known as the Geocentric Datum for Malaysia 2000 (GDM2000), and was adopted by the Department of Surveying and Mapping Malaysia (DSMM) on 26th August 2003
It consists of 100+ station positions at epoch 2020.0, station velocities and Post-Seismic Deformation (PSD) parametric models for stations subjected to major earthquakes
This study presents the concept of a time-dependent geodetic datum for Malaysia to clearly address the following issues: i) enhancing GDM2000 as a time-dependent geodetic datum; ii) time-dependent reference frame transformation from ITRF2000 to ITRF2014; iii) modelling the MyRTKnet station velocities and post-seismic deformation; iv) realization of new time-dependent geodetic reference frame based on ITRF2014; and v) implications on cadastral, mapping and GIS databases
Summary
The nonlinear station motions in MGRF2020 were modelled as in ITRF2014 with an enhanced combination strategy, including seasonal (annual and semiannual) signals of station positions, co-seismic jump detections and PSD for sites that were subject to major earthquakes As such the station position time series are approximated by piecewise linear trends (i.e. an initial position and velocity estimate that are updated whenever (coseismic) position jumps occur), and superimposed with non-linear position corrections (de ned after each seismic event) that account for the total accumulated post-seismic deformation (PSD). We use a grid model to regionally estimate the amount of cumulative co-seismic+PSD correction for the semi-kinematic reference frame
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