Active Tectonics across the Indo-Burma Range

Patcharaporn Maneerat

Published August 14, 2018, SCEC Contribution #8571, 2018 SCEC Annual Meeting Poster #243

The potentially active tectonics of the oblique subduction zone across the Indo-Burman Range (IBR), which formed due to India-Eurasia continent-continent collision in the Paleogene (Mitchell, 1993), remains controversial. To address the poorly understood kinematics of faulting and associated deformation, we study evidence of active tectonics by investigating the geomorphology, active crustal deformation and seismicity of the IBR. Geomorphic indices, such as the steepness index and hypsometric integral, geodetic measurements, and focal mechanism of the earthquakes occurred across IBR are used to investigate evidence for active surface uplift, crustal deformation, and stress orientations. We calculated geomorphic indices, and used GPS data from Steckler et al. (2016) and Kreemer et al. (2014) to generate strain-rate maps across our study region. We determined stress orientation and stress ratio using an inversion from the focal mechanisms of the events which occurred across the IBR. The geomorphic data suggest that the higher uplift rates are distributed across the IBR, especially in areas between the Kabaw and Churachanpur Mao Faults. Moreover, the geodetic strain maps indicate a significant component of contraction across the study region. Despite this, a lack of full GPS station coverage, specifically in the southern IBR, means we cannot conclude that oblique subduction is active. Furthermore, the principal stress directions obtained from stress inversion of the earthquake focal mechnism suggest strike-slip motion across IBR. The shortening direction is likely orientated in NW-SE. Further analysis is required in this area, and we will work more on the geomorphology at stream scales, including stream profiles, valley-width-height ratio of channels, and knickpoints since these channels likely capture tectonic perturbations. We will also continue working on improving the GPS strain maps by including elastic block models in the analysis. We are planning to investigate changes in angles between maximum principal stress and the slab interface, and compare our results with other subduction regions (Hardebeck, 2015). By investigating both long- and short-term processes, we hope to apply these observations and measurements to constrain a conceptual model of the active tectonics of the IBR and improve our understanding of the associated seismic hazard from the subduction thrust and crustal faults.

Citation
Maneerat, P. (2018, 08). Active Tectonics across the Indo-Burma Range. Poster Presentation at 2018 SCEC Annual Meeting.

Related Projects & Working Groups
Earthquake Geology