IASPEI - Picture Gallery

IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS014 Poster presentation 2319
Simulation of earthquake processes by finite element method: the case of
megathrust earthquakes on the Sumatra subduction zone
Dr. Shoubiao Zhu
Geophysics Institute of Crustal Dynamics, CEA IASPEI
Huilin Xing, Furen Xie, Yaolin Shi
Numerical simulation of the earthquake processes is a key method to carry out physical accurate
earthquake forecast in the future, but today empirical method is used in earthquake prediction, which is
seldom successful. In this paper, we use a unified rate-dependent frictional law to formulate two
different frictional states, one is sticking, and another is sliding. Based on R-minimum, time integration
method with static explicit is adopted in finite element analysis in order to make the result convergent in
calculation. Taken the Sumatra subduction zone as an example, where the major earthquake with
Mm=9.3 occurred in 2004, the process of locking, unlocking, and sliding between the subduction plate
and the overriding plate is modeled. There are 72000 hexahedral elements with 80820 nodes in the
model, which covers some areas of the India Ocean plate, of the Sunda subplate, and the Sumatra-
Andaman subduction zones. Contact elements are used to model the behaviors of the subduction in
finite element computation. The boundary conditions are applied to the model according to GPS
measurements. The media in the study areas is regarded as linear elastic with the Young's modulus
being 70GPa, and Poisson ratio 0.25, and the density is chosen as 2700kg/m3. The computed result
shows that a large area of homogeneous media with the same frictional coefficient is a prerequisite for
forming large scale of sudden sliding, which is regarded as an event. The earthquakes simulated by the
model on the Sumatra subduction zone have characteristics of quasi-cycle in time and of transference in
space. The rupture causing earthquakes propagates from down to upward. Moreover, the geometry of
the subduction zone has much influence on the location of the large event.
Keywords: finite element, frictional contact, sumatra subduction zone