The Tectonic Challenge of Indonesia
Indonesia sits at the collision point of the Eurasian, Indo-Australian, Pacific, and Philippine Sea tectonic plates. This causes continuous, massive crustal deformation and frequent earthquakes (like the 2004 Sumatra and 2018 Palu events), which physically displace the land surface.
From DGN95 to SRGI2013
The previous national datum, DGN95, was static. Due to tectonic slip, physical ground coordinates drifted away from their published DGN95 values by meters over the span of a decade.
To solve this, Indonesia's Geospatial Information Agency (BIG) implemented SRGI2013 (Sistem Referensi Geospasial Indonesia 2013). SRGI2013 is a semi-dynamic datum. It assigns coordinates referenced to a specific epoch (2012.0) but incorporates a national velocity model to account for continuous tectonic plate motion and co-seismic deformation from major earthquakes.
Surveying Risk in Indonesia
- Epoch Alignment: Surveyors must process GNSS baselines using the SRGI2013 velocity grid to translate current satellite observations back to the reference epoch. Failing to do so creates systematic offsets exceeding 1 meter.
- Boundary Disputes: Cadastral parcels registered in DGN95 or older local datums (like Batavia) do not align with modern SRGI2013 measurements, requiring rigorous block adjustments during property transfer.
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