Study on 2-D Crustal Shear Wave Splitting Tomography along The Sunda-Banda Arc Transition Zone

Southeast Asian Conference on Geophysics

Syuhada, Syuhada^1,2 ; Hananto, Nugroho D.^3 ; Abdullah, Chalid I.^4 ; Puspito, Nanang T.^5 ; Yudistira, Tedi^5 ; Anggono, Titi^1

Research Centre for Physics, Indonesian Institute of Sciences (LIPI), Tangerang, Indonesia^1

Graduate Research on Earthquake and Active Tectonics (GREAT), Institut Teknologi Bandung, Indonesia^2

Research Centre for Geotechnology-LIPI, Bandung, Indonesia^3

Faculty of Earth Sciences and Technology, Institut Teknologi Bandung, Indonesia^4

Global Geophysics Research Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Indonesia^5

关键词: Broad-band seismic stations;    Crustal deformations;    Distribution patterns;    First-order approximations;    Geological features;    Geological structures;    Oceanic lithosphere;    Shear wave splitting;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/62/1/012054/pdf
DOI  :  10.1088/1755-1315/62/1/012054

来源: IOP

【 摘 要 】

The Sunda-Banda Arc transition zone is an active region characterized by a change in tectonic regime from subduction of Indo-Australia oceanic lithosphere along the eastern part of Sunda Arc to collision of the Australian continental crust with islands arc in the western part of the Banda Arc. This complicated tectonic setting causes this area is an ideal place to study the crustal deformation along the plate boundary. The density contrast between the Australian continental crust and Indo-Australia oceanic crust in the transition zone may cause large stresses around the boundary between them. These plate boundary forces may control the distribution pattern of the deformation in the subduction to collision transition zone. The geometry of this deformation can be investigated using shear wave splitting (seismic anisotropy) study. We conduct shear wave splitting measurements from local earthquakes recorded at 17 broadband seismic stations around the Sunda-Banda arc transition zone. The 2D delay time tomography is then applied to determine the first order approximation of lateral varying anisotropic layers due to the local effect of geological structures. We observe strong anisotropy regions which coincide with the geological features as possible causes of anisotropy in the Sunda-Banda Arc transition zone. For instance, the high anisotropy zone found in Timor Island can be related to the alignment of metamorphic and igneous rocks, whereas the high anisotropy area around Sumba Island might correspond to the interaction of Sumba basement with the Australian margin increasing the frictional strength at the plate boundary.