Articles | Volume 10, issue 9
Nat. Hazards Earth Syst. Sci., 10, 1899–1911, 2010

Special issue: The GITEWS Project (German-Indonesian Tsunami Early Warning...

Nat. Hazards Earth Syst. Sci., 10, 1899–1911, 2010

  10 Sep 2010

10 Sep 2010

Bathymetry of the Indonesian Sunda margin-relating morphological features of the upper plate slopes to the location and extent of the seismogenic zone

A. Krabbenhoeft1, R. W. Weinrebe1, H. Kopp1, E. R. Flueh1, S. Ladage2, C. Papenberg1, L. Planert1, and Y. Djajadihardja3 A. Krabbenhoeft et al.
  • 1Leibniz Institute of Marine Sciences at Kiel University (IFM-GEOMAR), Wischhofstr. 1–3, 24149 Kiel, Germany
  • 2Federal Institute for Geosciences and Natural Resources (BGR), Stilleweg 2, 30655 Hannover, Germany
  • 3Agency for the Assessment and Application of Technology, J1. M.H. Thamrin No. 8, Jakarta 10340, Indonesia

Abstract. Earthquake history shows that the Sunda subduction zone of the Indonesian margin produces great earthquakes offshore Sumatra, whereas earthquakes of comparable magnitude are lacking offshore Java and the Lesser Sunda islands. Morphological structures in multibeam bathymetric data across the forearc relate with the extent of the seismogenic zone. Its updip limit corresponds to the slope break, most distinct off Java and Lesser Sunda islands, where we find coincident narrow, uniform, continuous outer arc ridges. Their landward termination and a shallow upper plate mantle mark the downdip limit of the seismogenic zone. In contrast the outer arc ridges off Sumatra are wider and partly elevated above sea level forming the forearc islands. The downdip limit of the seismogenic zone coincides with a deeper upper plate mantle. Sunda Strait marks a transition zone between the Sumatra and Java margins. We find the differences along the Sunda margin, especially the wider extent of the seismogenic zone off Sumatra, producing larger earthquakes, to result from the interaction of different age and subduction direction of the oceanic plate. We attribute a major role to the sediment income and continental/oceanic upper plate nature of Sumatra/Java influencing the composition and deformation style along the forearc and subduction fault.