Exciting news! We're transitioning to the Statewide California Earthquake Center. Our new website is under construction, but we'll continue using this website for SCEC business in the meantime. We're also archiving the Southern Center site to preserve its rich history. A new and improved platform is coming soon!

Kinematic modelling of neotectonics in the Persia-Tibet-Burma Orogen

Zhen Liu, & Peter Bird

Published February 2008, SCEC Contribution #9097

We apply a new kinematic modelling technique (program NeoKinema) to estimate neotectonic flow in the Persia-Tibet-Burma orogen. The models fit geodetic benchmark velocities, geological fault slip rates and stress directions (seismic moment tensor orientations) using a weighted-least-squares method. Models predict long-term velocities, anelastic strain rates and preferred fault slip rates averaged over timescales of 104–106 yr. While we find a few regions of low anelastic strain rate, the mean continuum strain rate in the preferred model is 2.2 × 10−16 s−1 (0.7 per cent Ma−1), so the India-Eurasia collision should not be modelled as an interaction between rigid microplates. For most faults, preferred fault slip rates agree with geological slip rates within their uncertainty bounds; this suggests that deformation imaged by geodesy over tens of years is consistent with deformation over 104–106 yr (given appropriate elastic corrections). We also calculate maps of long-term-average seismicity rate based on model fault slip rates and anelastic strain rates in the continuum, using the seismicity parameters of most comparable type of plate boundary. The pattern is generally in agreement with actual m > 5.67 earthquakes in the CMT catalogue (1977–2002), except that the Himalayan front, High Zagros and Altyn Tagh zones have been quieter than predicted. The spatial integral of our forecast over the orogen is 371 m > 5.67 earthquakes/25.75 yr, versus 238 which actually occurred. If this discrepancy has high significance, it means that some step(s) in our forecast method are faulty (such as the assumption of equal coupled seismogenic thickness in all continental convergent boundaries). If it is only an artefact of stochastic time-dependence, then this may have occurred in the orogen, in the external calibration region, or in both. Independent evidence suggests that large earthquakes (with many aftershocks) will occur along the Himalayan front in the future, possibly reducing this discrepancy.

Liu, Z., & Bird, P. (2008). Kinematic modelling of neotectonics in the Persia-Tibet-Burma Orogen. Geophysical Journal International, 172(2), 779-797. doi: 10.1111/j.1365-246X.2007.03640.x.