Estimation of the drift and deformations of the Indian plate using GPS repeat measurements

Future Work
Detailed analysis of the data is being taken up in the second phase of this study. The future work would involve:

• Estimating the components of the deformations, in order to plot the deformation vectors.
• Reprocessing the data using precise orbit data, to improve accuracy
• Using the plate velocity model to eliminate the velocity effects of the reference stations.
• Processing the data using the scientific GPS data processing software BERNESE and GAMIT and comparing the results with those obtained by using Trimble GPSurvey 2.30 software.
• Data collection at the stations for more epochs, and analyzing the data over a longer period to improve the accuracy of estimation of the plate motion.
• Estimating Crustal deformation parameters using these results.

Fig 4

Conclusions

Large amount of GPS data has been collected under the National GPS for Geodynamics Program initiated by DST, however detailed analysis is necessary, to achieve significant results. The efforts made in this case study is a step in that direction. Even though the results are of intermediate nature, hence inconclusive, they validate the quality, homogeneity and information content of the data. Once the detailed analysis is completed significant results can be expected. This research is expected to yield estimates of the Indian Plate motion, regional deformations (intra-plate motion) and local deformations within the region. This technique would be useful to the INGOs, NGOs, Government and UN Agencies and researchers who are studying the behavior of the Earths crust and working on the problems like earthquake prediction, as it demands high accuracy and reliability. The GPS technique would meet the accuracy requirements, inspite of being economical.

Acknowledgements
The data of the 3 local stations used in the study and the GPSurvey and Bernese software have been made available by IIG. The authors gratefully acknowledge the valuable assistance extended by the Director and the Scientists of IIG in this study. The data processing and the analysis have been carried out by H. V. Save under the guidance of Prof. M. N. Kulkarni, at the Department of Civil Engineering, IIT Bombay.

Reference

• Bilham et. al., 1995; Entertaining a great Earthquake in Western Nepal…, Journal of Nepal Geo. Society.
  
  
• DST, 1998; Report of the National GPS Expert Group on GPS for Geodynamics Programme, submitted to DST, compiled by M. N. Kulkarni.
  
  
• IGS, 1998; Report of the International GPS Service for Geodynamics, IGS Bureau, JPL, NASA, USA.
  
  
• IIG, 1998; Report on the GPS work in the Peninsular India by IIG.
  
  
• Kulkarni, 1999; 'Application of Geodesy to Monitor Earthquake Hazard: An Overview,' GIS at Development vol 3.3, CSDMS, NOIDA

Table 1: Results for Plate Motion

Baseline		Slope Length (m)		Difference (m)	Baseline s. d. (mm)		Deformation s. d. (mm)
From	To	98	99	(99 – 98)	98	99
POL2	IISC	3262461.721	3262461.408	- 0.313	10.996	63.685	64.62733
POL2	Mandangad	2720715.292	2720715.059	- 0.233	6.663	58.086	58.4669
POL2	Pune	2657487.891	2657487.589	- 0.302	9.820	60.568	61.3589

Table 2: Results for Intra-Plate (regional) Deformations

Baseline		Slope Length (m)		Difference (m)	Baseline s. d. (mm)		Deformation s. d. (mm)
From	To	98	99	(99 – 98)	98	99
IISC	Mandangad	717395.900	717395.965	0.065	2.794	3.380	4.385298
IISC	Pune	730889.596	730889.671	0.075	3.412	3.450	4.852241
IISC	Unhere	769669.920	769670.020	0.100	2.792	3.497	4.474849

Table 3: Results for Local Deformations

Baseline		Slope Length (m)		Difference (m)	Baseline s. d. (mm)		Deformation s. d. (mm)
From	To	98	99	(99 – 98)	98	99
Unhere	Mandangad	64102.633	64102.642	0.09	0.240	0.277	0.366509
Unhere	Pune	64566.479	64566.493	0.140	0.323	0.285	0.43076
Mandangad	Pune	86809.300	86809.307	0.007	0.625	0.569	0.845214