Dislocation Modelling of the 1997-2009 High-Precision Global Positioning System Displacements in Darjiling- Sikkim Himalaya, India

We used high-precision Global Positioning System
(GPS) to geodetically constrain the motion of stations in the
Darjiling-Sikkim Himalayan (DSH) wedge and examine the
deformation at the Indian-Tibetan plate boundary using IGS
(International GPS Service) fiducial stations. High-precision GPS
based displacement and velocity field was measured in the DSH
between 1997 and 2009. To obtain additional insight north of the
Indo-Tibetan border and in the Darjiling-Sikkim-Tibet (DaSiT)
wedge, published velocities from four stations J037, XIGA, J029 and
YADO were also included in the analysis. India-fixed velocities or
the back-slip was computed relative to the pole of rotation of the
Indian Plate (Latitude 52.97 ± 0.22º, Longitude - 0.30 ± 3.76º, and
Angular Velocity 0.500 ± 0.008º/ Myr) in the DaSiT wedge.
Dislocation modelling was carried out with the back-slip to model the
best possible solution of a finite rectangular dislocation or the
causative fault based on dislocation theory that produced the
observed back-slip using a forward modelling approach. To find the
best possible solution, three different models were attempted. First,
slip along a single thrust fault, then two thrust faults and in finally,
three thrust faults were modelled to simulate the back-slip in the
DaSiT wedge. The three-fault case bests the measured displacements
and is taken as the best possible solution.

• Kutubuddin Ansari
• Malay Mukul
• Sridevi Jade

• Global Positioning System
• Darjiling-Sikkim Himalaya
• Dislocation modelling.

[1] Jade, S., Bhattacharyya, A. K., Mukul, M., Jaganathan, S., Vijayan, M.
S. M., Tiwari, R. P.,Kumar, A; Kalita, S., Kumar, A., Krishna, A. P.,
Sahu, S. C., Murthy, M. V. R. L., Gupta, S. S. and Gaur, V. K. (2007).
Estimates of interseismic deformation in Northeast India from GPS
measurements, Earth and Planetary Science Letters, 263, 221–234.
[2] Toda, S., Stein, R., Lin, J. and Sevilgen, V., "Coulomb 3.2 Graphic-rich
deformation & Stress-change software for earthquake, tectonic and
volcano research teaching”, 2010 (user guide).
[3] P. Cervelli, M.H. Murray, P. Segall, Y. Aoki and T. Kato., "Estimating
Source parameter from deformation data with an application to the
March 1997 earthquake swarm of the Izu Penisula, Japan” Journal of
Geophysical Research, Vol. 106(10), 2001, p.11217-11237.
[4] Nikolas I. Christensen, "Poisson ratio and crustal seismology”, Journal
of Geophysical Research, Vol. 101(B2), 1996, p. 3139-3156.
[5] Mukul, M., Jade, S., Ansari, K. and Matin, A., "Seismotectonic
implications of strike-slip earthquakes in the Darjiling–Sikkim
Himalaya” Current Science, vol. 106(2), 2014, p. 126-131.
[6] Banerjee, P., Burgmann, R., Nagarajan, B. and Apel, E., "Intraplate
deformation of the Indian subcontinent” Geophysical Research Letters,
vol. 35, L18301, doi: 10.1029/ 2008GL035468, 2008.
[7] Wang, Q., Zhang, P. Z., Freymueller, J. T., Bilham, R., Larson, K. M.,
Lai, X., You, X., Niu, Z., Wu, J., Li, Y., Liu, J., Yang, Z. and Chen, Q.,
"Present-day crustal deformation in China constrained by global
positioning system measurements” Science, vol. 294, 2001, p. 574-577.