HR: 1330h
AN: G43B-07    [Abstracts]
TI: Modeling Uncertainty in Fault Locations and Earthquake Rupture Configurations in Northwest Anatolia
AU: * Muller, J R
EM: jmuller@core2.gsfc.nasa.gov
AF: NASA Goddard Space Flight Center, Planetary Geodynamics Lab Mail Code 698, Greenbelt, MD 20771 United States
AU: Aydin, A
EM: aydin@pangea.stanford.edu
AF: Stanford University, Dept. of Geol. and Envir. Sci. 450 Braun Hall, Bldg. 320, Stanford, CA 94305 United States
AB: Active faulting and earthquakes almost always pose uncertainties in the subsurface configuration of faults and the extent of rupture. We here identify three geometric uncertainties in the location and extend of rupture due to incomplete historical data and/or submarine environments along the North Anatolian Fault and discuss an approach for evaluating endmember fault geometry and rupture scenarios. The first case is that of the uncertainty in the location of the western end of the 1967 Mudurnu earthquake due to limited data. We identified three potential rupture geometries based on field observations and tested them using a boundary element model and a posteriori constraint provided by the next rupture, the 1999 Izmit earthquake. We find that for three different potential 1967 Mudurnu Valley rupture scenarios there are positive Coulomb stress changes at the hypocenter of the 1999 Izmit earthquake. We also find, however, that only for the scenario where subsurface rupture in the 1967 event extends towards Lake Sapanca does an Izmit rupture segment receive greater Coulomb stress change than any other neighboring fault. The second case deals with the uncertainty in the western end of the 1999 Izmit earthquake. We have used ground surface displacements from InSAR interferometry and GPS data to constrain the distribution and western termination of Izmit slip and evaluate the most likely stress change scenarios on faults in the eastern Marmara Sea. The fault slip inversions indicate that Izmit earthquake slip extended at least twelve kilometers west of the Hersek Delta into the Marmara Sea, but that the orientation of the rupture past Hersek Delta is not well constrained. Testing several possible western rupture configurations, we find that either the Princes' Islands or Cinarcik fault may be most susceptible to future failure. The third case is the uncertainty associated with the fault configuration under the Marmara Sea. Using mechanical modeling, we test three configurations of the fault system within the Marmara Sea fault proposed by others and show that an interpretation with a series of pull-apart basins along a master strike-slip fault best produces the observed deformation pattern within the Marmara Sea. In the model, crustal faults within the Marmara Sea slip in accordance with GPS-constrained slip rates along deep plate boundary dislocations. The locations and relative subsidence of the basins along the northern Marmara trough are well matched by our model results. This method shows the ability for mechanical modeling to evaluate fault configuration models that are otherwise equally justified by interpretation of seismic reflection data.
DE: 7209 Earthquake dynamics and mechanics
DE: 8010 Fractures and faults
DE: 8107 Continental neotectonics
SC: Geodesy [G]
MN: 2005 Joint Assembly