Open AccessDetermining the Sula block kinematics in the triple junction area in Indonesia by GPS
Author(s) -
Walpersdorf Andrea,
Vigny Christophe,
Manurung P.,
Subarya C.,
Sutisna S.
Publication year - 1998
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1046/j.1365-246x.1998.00641.x
Subject(s) - triple junction , geology , clockwise , seismology , tectonics , geodesy , global positioning system , block (permutation group theory) , rotation (mathematics) , deformation (meteorology) , geometry , geophysics , telecommunications , oceanography , mathematics , computer science
Summary The point of convergence of the Eurasian, Philippine and Australian plates is situated adjacent to the island of Sulawesi, Indonesia. The relative plate velocities are estimated by NUVEL1 to be 7 to 9 cm yr − 1 . The complex tectonic mechanism of the triple junction has been studied over a two‐year period in the course of the GEODYSSEA Southeast Asian Project. The GPS investigations concentrate on measurements of both the Sulawesi (eastern Indonesia) part of the inter‐regional GEODYSSEA network and a local subnetwork on Sulawesi. Motions derived using data from the subnetwork confirm what the results of the inter‐regional GEODYSSEA network have suggested; that is, that current deformation is high, and there are distinct deformation domains in the study area on Sulawesi. The tectonic mechanism of the triple junction has been analysed using a rigid microblock model. The triple junction area can best be interpreted as a headland of the Australian Plate deflected by its collision with the Philippine Plate, thereby identifying the driving forces of the current deformation. The northern part is dominated by the Sula domain, which shows clockwise rotation. To the south, it is connected to the Australian Plate by an ensemble of microblocks undergoing counter‐clockwise rotation. In addition to the above, our tectonic model permits the determination of the local influence of two large earthquakes ( M =7.8, 1996 January 1 and M =7.0, 1996 July 22) on the motion of the station Tomini (north Sulawesi). More observations and a denser GPS network are planned in order to study the behaviour of the Palu‐Koro Fault, the main fault on the western limit of the Sula block.