Geodynamics of S.E. Asia: First results of the Sulawesi 1998 GPS campaign

Simons, Wim; Loon, Danny van; Walpersdorf, Andréa; Ambrosius, B. A. C.; Kahar, Joenil; Abidin, Hasanuddin Z.; Sarsito, Dina A.; Vigny, Christophe; Abu, Samad; Morgan, Peter

doi:10.1007/978-3-642-59742-8_44

Cited by 5 publications

(5 citation statements)

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“…The Sulawesi island has been characterized by the rapid block‐like rotation of the northeastern part in first‐approximation [ Walpersdorf et al , 1998; Stevens et al , 1999; Simons et al , 2000; Bock et al , 2003]. Analysis of the dense Sulawesi subset (Figure 7) enables the identification of four microblocks (discussed in detail by Socquet et al [2006a]).…”

Section: Sundaland Boundaries Motion and Deformationmentioning

confidence: 99%

A decade of GPS in Southeast Asia: Resolving Sundaland motion and boundaries

et al. 2007

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A unique GPS velocity field that spans the entire Southeast Asia region is presented. It is based on 10 years (1994–2004) of GPS data at more than 100 sites in Indonesia, Malaysia, Thailand, Myanmar, the Philippines, and Vietnam. The majority of the horizontal velocity vectors have a demonstrated global accuracy of ∼1 mm/yr (at 95% confidence level). The results have been used to (better) characterize the Sundaland block boundaries and to derive a new geokinematic model for the region. The rotation pole of the undeformed core of the Sundaland block is located at 49.0°N–94.2°E, with a clockwise rotation rate of 0.34°/Myr. With respect to both geodetically and geophysically defined Eurasia plate models, Sundaland moves eastward at a velocity of 6 ± 1 to 10 ± 1 mm/yr from south to north, respectively. Contrary to previous studies, Sundaland is shown to move independently with respect to South China, the eastern part of Java, the island of Sulawesi, and the northern tip of Borneo. The Red River fault in South China and Vietnam is still active and accommodates a strike‐slip motion of ∼2 mm/yr. Although Sundaland internal deformation is general very small (less than 7 nanostrain/yr), important accumulation of elastic deformation occurs along its boundaries with fast‐moving neighboring plates. In particular in northern Sumatra and Malaysia, inland‐pointing trench‐perpendicular residual velocities were detected prior to the megathrust earthquake of 26 December 2004. Earlier studies in Sumatra already showed this but underestimated the extent of the deformation zone, which reaches more than 600 km away from the trench. This study shows that only a regional Southeast Asia network spanning thousands of kilometers can provide a reference frame solid enough to analyze intraplate and interplate deformation in detail.

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Section: Sundaland Boundaries Motion and Deformationmentioning

confidence: 99%

A decade of GPS in Southeast Asia: Resolving Sundaland motion and boundaries

et al. 2007

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“…The solution includes ∼190 stations spanning 11 years of data from 1991 to 2002. We processed new data: the permanent Malaysian network acquisitions from 1999 to 2001, the Asia Pacific Regional Geodetic Project campaigns from 1997 to 2000 [ Govind et al , 1999], the first‐order Thai network measurements in 1994–1996–2000 and data from Hyderabad GPS station in India from 1996 to 2000, as well as already published data: GEODYSSEA data [ Chamot‐Rooke and Le Pichon , 1999; Michel et al , 2001; Simons et al , 1999], GPS campaigns in Sulawesi from 1999 to 2002 [ Simons et al , 2000; Vigny et al , 2002; Walpersdorf et al , 1998a, 1998b], Myanmar campaigns in 1998 and 2000 [ Vigny et al , 2003], west Nepal network measurements in 1991–1995–1997–1998–2000 [ Bilham et al , 1997; Jouanne et al , 1999; Larson et al , 1999], the Kathmandu transect campaigns from 1998 to 2000 [ Avouac et al , 2001; Jouanne et al , 2004] and data from 30 IGS stations world wide spread (Figure 1). The raw GPS measurements were analyzed in 24‐hour daily solutions with GAMIT [ King and Bock , 1999].…”

Section: Data Processingmentioning

confidence: 99%

India and Sunda plates motion and deformation along their boundary in Myanmar determined by GPS

et al. 2006

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[1] Using a regional GPS data set including $190 stations in Asia, from Nepal to eastern Indonesia and spanning 11 years, we update the present-day relative motion between the Indian and Sundaland plates and discuss the deformation taking place between them in Myanmar. Revisiting measurements acquired on the Main Boundary Thrust in Nepal, it appears that points in southern Nepal exhibit negligible deformation with respect to mainland India. Including these points, using a longer time span than previous studies, and making an accurate geodetic mapping in the newest reference frame allows us to refine the present-day Indian motion. Our results confirm that the current motion of India is slower than predicted by the NUVEL-1A model, and in addition our India-Eurasia motion is significantly ($5 mm/yr) slower than previous geodetic determinations. This new Indian motion, combined with a refined determination of the Sundaland motion, gives way to a relative India-Sunda angular velocity of 20.2°N, 26.1°E, 0.370°/Myr in ITRF2000, predicting a relative motion of 35 mm/yr oriented N10°at the latitude of Myanmar. There, the Sagaing Fault accommodates only 18 mm/yr of right-lateral strike slip, only half of the shear component of motion. We present two models addressing how and where the remaining deformation may occur. A first model of distributed deformation implies convergence on the Arakan subduction (the northern continuation of the now famous Sumatra-Andaman Trench) and wrench faulting in the Arakan wedge. The second model uses localized deformation, where deformation observed west of the Sagaing Fault is entirely due to elastic loading on a faster and oblique Arakan subduction (23 mm/yr). This latter model predicts that a major earthquake of M w 8.5 may occur every century on this segment of the subduction.

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“…[3] Because the triple junction between the Philippine Sea, Australian, and Sunda plates in Southeast Asia is highly seismically active and is characterized by rapid rotations of small blocks revealed by both geological and kinematic studies [Fitch and Hamilton, 1974;Hamilton, 1972;Kreemer et al, 2000;Silver et al, 1983a;Silver and Moore, 1978;Simons et al, 2000;Stevens et al, 1999;Vigny et al, 2002;Walpersdorf et al, 1998aWalpersdorf et al, , 1998b (Figure 1), it constitutes a type example of how a collision can be accommodated by block rotation instead of mountain building. However, to more fully understand this process, a more precise description of these microblock's motions and a better understanding of the main active structures of the area are necessary.…”

Section: Introductionmentioning

confidence: 99%

Microblock rotations and fault coupling in SE Asia triple junction (Sulawesi, Indonesia) from GPS and earthquake slip vector data

et al. 2006

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The island of Sulawesi, eastern Indonesia, is located within the triple junction of the Australian, Philippine, and Sunda plates and accommodates the convergence of continental fragments with the Sunda margin. We quantify the kinematics of Sulawesi by modeling GPS velocities and earthquake slip vectors as a combination of rigid block rotations and elastic deformation around faults. We find that the deformation can be reasonably described by a small number of rapidly rotating crustal blocks. Relative to the Sunda Plate, the southwestern part of Sulawesi (Makassar Block) rotates anticlockwise at ∼1.4°/Myr. The northeastern part of Sulawesi, the Bangai‐Sula domain, comprises three blocks: the central North Sula Block moves toward the NNW and rotates clockwise at ∼2.5°/Myr, the northeastern Manado Block rotates clockwise at ∼3°/Myr about a nearby axis, and East Sulawesi is pinched between the North Sula and Makassar blocks. Along the boundary between the Makassar Block and the Sunda Plate, GPS measurements suggest that the trench accommodates ∼15 mm/yr of slip within the Makassar Strait with current elastic strain accumulation. The tectonic boundary between North Sula and Manado blocks is the Gorontalo Fault, moving right laterally at about 11 mm/yr and accumulating elastic strain. The 42 mm/yr relative motion between North Sula and Makassar blocks is accommodated on the Palu‐Koro left‐lateral strike‐slip fault zone. The data also indicate a pull‐apart structure in Palu area, where the fault shows a transtensive motion and may have a complex geometry involving several active strands. Sulawesi provides a primary example of how collision can be accommodated by crustal block rotation instead of mountain building.

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Geodynamics of S.E. Asia: First results of the Sulawesi 1998 GPS campaign

Cited by 5 publications

References 5 publications

A decade of GPS in Southeast Asia: Resolving Sundaland motion and boundaries

A decade of GPS in Southeast Asia: Resolving Sundaland motion and boundaries

India and Sunda plates motion and deformation along their boundary in Myanmar determined by GPS

Microblock rotations and fault coupling in SE Asia triple junction (Sulawesi, Indonesia) from GPS and earthquake slip vector data

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