International Lithosphere Program Task Force III: The seismic cycle at continental transforms from seismological observation and forward simulation

Duration: 2015-2020

Funding: ILP International Lithosphere Program

PIs: Oliver Heidbach and Marco Bohnhoff

Key Partner: Fabrice Cotton (GFZ Section 2.6), Tobias Hergert (TU Darmstadt), Hideo Aochi (BRGM, France), Ben-Avraham (University of Tel Aviv, Israel), Yehuda BenZion (University of Southern California, USA), Ulubay Ceken (AFAD/Disaster and Emergency Management Presidency, Ankara/Turkey), Georg Dresen (GFZ Section 4.2, William L. Ellsworth (USGS Menlo Park, USA), Hisao Ito (JAMSTECT, Japan), Peter E. Malin (ASIR, USA), Dave Mencin (UNAVCO), Marcos Moreno (GFZ Section 4.1), Sinan Özeren (ITU, Turkey), Mark D. Zoback (Stanford University, USA)

Project Webpage: www.scl-ilp.org

We contribute towards a better characterization of the kinematic setting of this key section of the North Anatolian Fault Zone (NAFZ). Given the recent activity on this topic the proposed task force will not start from scratch, but instead will build on extensive existing networks that were consolidated in the recent ILP period. In particular our networks involve key researchers from the disciplines such as experimental seismology, geomechanical-numerical modelling, fault-zone evolution and plate tectonics.

We will focus on the natural laboratory in the Marmara Sea region addressing key topics related to the model of the seismic cycle. Here a major (M>7) earthquake is overdue in direct vicinity to the population centre Istanbul and has to be considered as the major potential risk for the megacity. Here we intent to contribute to research at the forefront within the here proposed task force. The following three key topics are to be addressed with this Task Force:

  • Improving and further refining existing kinematic models for the NAFZ in northwestern Turkey based on world-class seismological waveform recordings from the recently implemented ICDP-GONAF downhole geophysical observatory (Prevedel et al., 2015).
  • Refining simulation of stress and strain accumulation by means of forward 3D geomechanical-numerical  models addressing key-questions such as a) What are the key ingredients for the next generation of numerical models that describe the complete stress tensor and its changes in space and time? b) Which is the most likely earthquake scenario for the seismic gap?, c) Is the central segment creeping or not?
  • Combine and integrate the scientific results from 1. and 2. towards a general model of the current setting of the Marmara seismic gap and its role in the current understanding of seismic cycles at transform faults worldwide. This is of particular relevance for improving our general understanding of geodynamic processes along strike-slip faults and - at least likewise important- its implications for seismic hazard assessment for nearby-located population centres.

In particular this Task Force will provide a platform and a network for young scientists to present and discuss their model concepts. Several PhD students are already involved in the previous studies leading to this proposal. The aim of the Task Force is to continue attracting young researchers as well as experienced experts that are willing to share their expertise in geomechanical modelling in order to jointly improve our knowledge of geodynamic processes. The Task Force is closely linked to Urban Fault Observatory Team Project of GFZ Section 2.6 where for this region the key project is MEMO – Marmara Sea Earthquake Modelling, that will start in late 2017.

Key References

  • Bohnhoff, M., Bulut, F., Dresen, G., Malin, P.E., Eken, T., Aktar, M (2013). An earthquake gap south of Istanbul. Nature Commun., 4:1999, doi.org/10.1038/ncomms2999
  • Hergert, T. and O. Heidbach (2010). Slip-rate variability and distributed deformation in the Marmara Sea fault system, Nature Geoscience, 3, 132-135, http:/doi.org/10.1038/NGEO739
  • Hergert, T., Heidbach,  O., Becel, A. and M. Laigle (2011). Geomechanical model of the Marmara Sea region - I. 3D contemporary kinematics, Geophys. J. Int. 185, http:/doi.org/10.1111/j.1365-1246X.2011.04991.x
  • Hergert, T. and O. Heidbach (2011). Geomechanical model of the Marmara Sea region - II. 3-D contemporary background stress field, Geophys. J. Int., http:/doi.org/10.1111/j.1365-1246X.2011.04992.x
  • Heidbach, O., and Z. Ben-Avraham. 2007, Stress evolution and seismic hazard of the Dead Sea fault system. Earth and Planetary Science Letters, 257,299-312.
  • Ickrath, M., Bohnhoff, M., Bulut, F., Dresen, G. Stress rotation and recovery in conjunction with the 1999 Izmit Mw7.4 earthquake. Geophys. J. Int., doi: 10.1093/gji/ggt409, 2014.
  • Moreno, M., C. Haberland, O. Oncken, A. Rietbrock, S. Angiboust and O. Heidbach, 2014, Locking of the Chile subduction zone controlled by fluid pressure before the 2010 earthquake, Nature Geosciences, doi:10.1038/ngeo2102.
  • Prevedel., B., Bulut, F., Bohnhoff, M., Raub, C., Kartal, R.F., Alver, F., Malin, P.E (2015). Downhole Geophysical Observatories: Best Installation Practices and a Case History from Turkey. Int. J.Earth Sci., doi.org 10.1007/s00531-015-1147-5
  • Reilinger, R., McClusky, S., Vernant, P., Lawrence, S., Ergintav, S., Cakmak, R., Ozener, H., Kadirov, F., Guliev, I., Stepanyan, R., Nadariya, M., Hahubia, G., Mahmoud, S., Sakr, K., ArRajehi, A., Paradissis, D., Al-Aydrus, A., Prilepin, M., Guseva, T., Evren, E., Dmitrosta, A., Filikov, S.V., Gomez, F., Al-Ghazzi, R. and G. Karam (2006). GPS constraints on continental deformation in the Africa-Arabia-Eurasia continental collision zone and implications for the dynamics of plate interaction. J. Geophys. Res. 111, doi.org/10.1029/2005JB004051

Kontakt

Profilfoto von  Priv. Doz. Dr. Oliver Heidbach

Priv. Doz. Dr. Oliver Heidbach
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