HR: 08:30h
AN: G41A-03    [Abstracts]
TI: Kinematic Behaviour and Active Tectonics of the SE Asia Triple Junction Inferred by GPS Measurements in Sulawesi (Eastern Indonesia)
AU: * Socquet, A
EM: anne@deos.tudelft.nl
AF: Department of Earth Observation and Space Systems DUT, Kluyverweg 1 , Delft, 2629 HS Netherlands
AU: Simons, W
EM: Wim.Simons@lr.tudelft.nl
AF: Department of Earth Observation and Space Systems DUT, Kluyverweg 1 , Delft, 2629 HS Netherlands
AU: Vigny, C
EM: vigny@geologie.ens.fr
AF: laboratoire de Geologie - Ecole Normale Superieure , 24 rue Lhomond, Paris, 75005 France
AU: Ambrosius, B
EM: B.A.C.Ambrosius@lr.tudelft.nl
AF: Department of Earth Observation and Space Systems DUT, Kluyverweg 1 , Delft, 2629 HS Netherlands
AU: Spakman, W
EM: wims@geo.uu.nl
AF: Faculty of Earth Sciences, Utrecht University, Budapestlaan 4, Utrecht, 3584 CD Netherlands
AU: Walpersdorf, A
EM: Andrea.Walpersdorf@obs.ujf-grenoble.fr
AF: Laboratoire de G‚ophysique Interne et Tectonophysique, Maison des G‚osciences 1381, rue de la Piscine, Saint-Martin-D'HŠres, 38400 France
AU: Subarya, C
EM: csubarya@bakosurtanal.go.id
AF: National Coordination Agency for Surveys and Mapping, BAKOSURTANAL Jl. Raya Jakarta - Bogor Km.46, Cibinong, 16911 Indonesia
AU: Sarsito, D
EM: d_sarsito@yahoo.com
AF: ITB, Jl. Ganesha 10, Bandung, 40132 Indonesia
AB: Sulawesi Island, eastern Indonesia, is located at the triple junction of the Australian, Philippine, and Sunda Plates generating a complicated configuration of active plates' boundaries. We quantify the kinematics and the active tectonics of Sulawesi and surrounding region based on 10 years of GPS measurements on a network which was expanded from 8 sites in 1994 up to more than 40 sites nowadays. In the Sunda reference frame, the northern part of Sulawesi Island, the Sula Block, moves quickly toward the NNW and rotates clockwise at ~3ø/Myr. The southern part, the South Sulawesi block, rotates in the opposite direction at ~2ø/Myr. The tectonic boundaries between these two blocks are materialized by the Matano Fault to the South, followed by Palu-Koro Fault to the West and ending northward into the Minahassa Trench limiting Sula and Sunda blocks. The South Sulawesi block can be considered as rigid in first approximation while the Sula block shows an important internal deformation. The Gorontalo fault has been evidenced by geology within the Sula domain. Although few seismicity has been reported, GPS measurements across the fault trace indicate about 8 mm/yr of right-lateral movement across Gorontalo fault with accumulation of interseismic elastic deformation. Moreover, extension on the Tomini Bay, identified by both GPS and seismicity, may indicate back-arc stretching behind Minahassa subduction. Most of the relative motion (about 30 mm/yr) between the two blocks is accommodated on the Palu-Koro and Matano left-lateral strike-slip faults. At the first order, the velocities measured across the Palu-Koro Fault can fit a dislocation model of a fault interseismically locked at 5-10 km. However, both recent GPS measurements and geomorphology analysis in the region of Palu City indicate that the fault presents there a pull-apart complex geometry distributing the motion on two parallel active locked faults. This fault continues northward and connects to the Minahassa Trench that accounts for the motion between Sula and Sunda Blocks. This trench is the location of many earthquakes and GPS time series show non-linear displacements on the subduction interface.
DE: 9320 Asia
DE: 8123 Dynamics, seismotectonics
DE: 1206 Crustal movements--interplate (8155)
DE: 1208 Crustal movements--intraplate (8110)
DE: 1243 Space geodetic surveys
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting