Lake Toba, situated atop the Indonesian subduction zone at the intersection of the Sumatra Fault and the Investigator Fracture Zone, is the largest know young caldera (100 kilometer diameter) which last erupted ca. 75.000 years ago. As a consequence of this the average temperature on Earth dropped 10 degrees. Studying this feature and its interaction with subduction, transform fault and asperities due to subducting oceanic features touches three of the GFZ POF topics. This piggy-back experiment to British offshore activities will explore the potential of this site for the future research – also in close interaction with GITEWS.

Time Frame

• Piggy-back to British off-shore experiment (May-June 2008; ca. 6+ weeks)

Principal Investigators

• T. Ryberg (GFZ Potsdam)
• M. Weber (GFZ Potsdam) 
• F. Tilmann (Uni. Cambridge)
• B. Kennett (Uni. Australia)

Cooperations

• Uni. Cambridge, ANU Australia National University

Methods & Equipment

• wide-angle seismic interpretation, controlled source seismic tomography localisation of volcano-related earthquakes

Publications/Results

• Stankiewicz, J., Ryberg, T., Haberland, Ch., Fauzi, Natawidjaja, D. (2010): Lake Toba volcano magma chamber imaged by ambient seismic noise tomography, Geophys. Res. Lett., 37, L17306, doi:10.1029/2010GL044211
• Lange, D., Tilmann, F., Rietbrock, A., Collings, R., Natawidjaja, D. H., Suwargadi, B. W., Barton, P., Henstock, T., Ryberg, T. (2010): The Fine Structure of the Subducted Investigator Fracture Zone in Western Sumatra as Seen by Local Seismicity, Earth and Planetary Science Letters, 298, 1-2, 47-56, doi:10.1785/0120090004

Additional Informationen

Targets & Aims

• Determination of crustal velocity structure around Lake Toba (incl. Sumatra Fault) and possibly between Nias Island and the coast using British air-gun sources (Pg and Pn phases). This will be the northern extension of the British study area
• Using local volcano-related events to study Lake Toba caldera + its relation to Sumatra Fault
• Supplying recordings of regional and teleseismic events recorded in our network to British partners for joint interpretatio
• Pre-study for potential future (on-land) controlled source study of Lake Toba and Sumatra Fault, the large on-land fault near Lake Toba
• Pre-study for potential future volcano-seismic study on Lake Toba