Crustal motion in Indonesia from Global Positioning System measurements

Abstract

We present the crustal motion velocity field for the Indonesian archipelago based on Global Positioning System (GPS) field surveys conducted from 1991 to 1997, and 2001, totaling more than 150 sites, as well as on a reanalysis of global tracking data in the Scripps Orbit and Permanent Array Center archive from 1991 to 2001 in International Terrestrial Reference Frame 2000. We compute poles of rotation for the Australia, Eurasia, and Pacific plates based on our analysis of the global GPS data. We find that regional tectonics is dominated by the interaction of four discrete, rotating blocks spanning significant areas of the Sunda Shelf, the South Banda arc, the Bird's Head region of New Guinea, and East Sulawesi. The largest, the Sunda Shelf block (SSH), is estimated to be moving 6 ± 3 mm/yr SE relative to Eurasia. The South Banda block (SBB) rotates clockwise relative to both the SSH and Australia plate, resulting in 15 ± 8 mm/yr of motion across the Timor trough and 60 ± 3 mm/yr of shortening across the Flores Sea. Southern New Guinea forms part of the Australia plate from which the Bird's Head block (BHB) moves rapidly WSW, subducting beneath the Seram trough. The East Sulawesi block rotates clockwise about a nearby axis with respect to the Sunda Shelf, thereby transferring east‐west shortening between the Pacific and Eurasia plates into north‐south shortening across the North Sulawesi trench. Except for the Sunda Shelf, the crustal blocks are all experiencing significant internal deformation. In this respect, crustal motion in those regions does not fit the microplate tectonics model.

A Probabilistic Tsunami Hazard Assessment for Western Australia

“…On the one hand, there are arguments that, because the Australian plate being pushed beneath Java is relatively old, the cooler temperature of the interplate contact will lead to a narrow seismogenic zone, hence smaller earthquakes can be expected off Java (RUFF and KANAMORI, 1980;HYNDMAN and WANG, 1993;OLESKEVICH et al, 1999). This argument is supported by the apparent lack of a wide zone of interplate coupling suggested by geodetic measurements (BOCK et al, 2003). Cooler temperatures would also lead to higher densities, lower buoyancy and potentially weaker coupling which may also influence the maximum magnitude and/or rate of seismic moment release.…”

“…An analysis of GPS measurements by BOCK et al (2003) has shown that the convergence rate between the Australian Plate and the islands of the Sunda Arc immediately to its north decreases dramatically east of Sumba. The convergence rate between the Australian Plate and Timor is low, while the islands further to the north (e.g., Sulawesi) are moving much faster towards Australia than Timor is.…”

Southeast Asia's changing palaeogeography

“…Southeast Asia is a region characterised by extremely high rates of plate convergence, which are amongst the highest on the planet. Global Positioning System (GPS) measurements (Bock et al 2003, Simons et al 2007) indicate rates of relative motions are typically more than several centimetres per year between plates and smaller tectonic fragments.…”

Landslide tsunami hazard in the Indonesian Sunda Arc

“…This leads to a narrower seismogenic zone and lower coupling between subducting and overriding plate which results in the absence of huge seismic events (Burbidge et al, 2008). Evidence for lower coupling comes also from GPS data, as motion vectors of Java, Bali and Sumbawa point eastward, despite northward subduction (Bock et al, 2003). It is clear that earthquakes are a primary trigger for submarine landslides.…”

“…Relative plate velocities between the Australian and the Sunda Plate increase from 60 mm/yr off Sumatra to 70 mm off Bali (Bock et al, 2003;Simons et al, 2007). Off Java and Bali, the Australian plates subducts nearly perpendicular to the trench, while slip partitioning takes place at the oblique subduction at Sumatra.…”