Poly3D Application 2:

Modeling of the 1999 Turkish earthquakes (after Jordan Muller, 2001)

The apparent triggering of the 1999 Izmit earthquake by the 1967 Mudurnu Valley earthquake was examined. Instead of rupturing directly ahead of the termination of the 1967 rupture along the Mountainfront fault, the 1999 earthquake ruptured fault segments several kilometers to the north. To test how stress loading conditions following 1967 could have favored the observed 1999 rupture, rupture along three different geometric configurations of the Mudurnu Valley earthquake fault, all permissable according to geological observations, were tested. The only case in which the Izmit segments receive stress loading for failure greater than the Mountainfront fault is shown.

Rupture traces for the three most recent large earthquakes along the NAF. Background 30m resolution Digital Elevation map processed by Eric Fielding, Oxford University available at Oxford University website. Note the jump of the Izmit to Sapanca segments away from the topographically well-defined mountainfront fault.

Fault map of the area. Fault in red is the 1967 ruptured segment.

Only for this Mudurnu Valley fault geometry is an Izmit earthquake fault segment more favored to fail than the Mountainfront fault. This test, using Poly3D, allows one to constrain the potential geometries of subruface earthquake rupture.

Model configuration

Coulomb stress changes for right-lateral slip along the Mountainfront fault and the Izmit earthquake rupture segments