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Crustal strain partitioning and the associated earthquake hazard in the eastern Sunda‐Banda Arc
Author(s) -
Koulali A.,
Susilo S.,
McClusky S.,
Meilano I.,
Cummins P.,
Tregoning P.,
Lister G.,
Efendi J.,
Syafi'i M. A.
Publication year - 2016
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl067941
Subject(s) - geology , seismology , block (permutation group theory) , clockwise , slip (aerodynamics) , java , island arc , tectonics , subduction , rotation (mathematics) , geometry , physics , mathematics , computer science , thermodynamics , programming language
We use Global Positioning System (GPS) measurements of surface deformation to show that the convergence between the Australian Plate and Sunda Block in eastern Indonesia is partitioned between the megathrust and a continuous zone of back‐arc thrusting extending 2000 km from east Java to north of Timor. Although deformation in this back‐arc region has been reported previously, its extent and the mechanism of convergence partitioning have hitherto been conjectural. GPS observations establish that partitioning occurs via a combination of anticlockwise rotation of an arc segment called the Sumba Block, and left‐lateral movement along a major NE‐SW strike‐slip fault west of Timor. We also identify a westward extension of the back‐arc thrust for 300 km onshore into East Java, accommodating slip of ∼6 mm/yr. These results highlight a major new seismic threat for East Java and draw attention to the pronounced seismic and tsunami threat to Bali, Lombok, Nusa Tenggara, and other coasts along the Flores Sea.