John Paul Puchakayala

The December 26th 2004, Mw 9.2 Sumatra-Andaman earthquake ruptured 1300–1500 km of the subduction mega thrust along the eastern boundary of the Indian and Australian plates. The nearly 500 km long Andaman segment, the northernmost stretch of the 2004 event, evidenced slower rupture propagation and less slip than other segments. It is the largest event since the 1960s and the first Mw > 9 earthquake to occur in the era of modern space geodesy and broadband seismology.

CERI responded to this event on the other side of the planet being the first to switch on a GPS receiver to monitor the post seismic deformation. Four continuous and 12 campaign sites were installed and maintained for the last nine years with NSF funding and UNAVCO facility support.

After nearly a decade of Sumatra-Andaman postseismic deformation studies, the Andaman GPS data, with the pre-2004 motion removed, continues to move in the direction it moved co-seismically on Dec 26th 2004. Sites that subsided ~100cm on that day recovered 43% of its subsidence. Some sites continue to uplift even to this day. Intriguingly, the uplift and right-lateral horizontal shear deformation observed at all Andaman sites are opposite the predictions of radially-symmetric viscoelastic relaxation models. This suggests either that these types of models oversimplify the laterally- and time-varying viscoelastic flow response, or that accelerated slip down-dip of a locked shallow megathrust continues to dominate the near-field motions. However, the existing viscoelastic models explain well the postseismic deformation at far field sites.

Therefore, there is reason to suspect the deformation of these islands are not following the book or the book need to be rewritten after constructing some realistic models.

My collaborators include Roger Bilham, C.P. Rajendran,
Tony Lowry, Vinod Gaur, Roland BurgmannRobert Smalley, and Samir Acharya.

Latest GPS Time Series



Field work Photos 



Slow Slip Acceleration beneath Andaman Islands Triggered by the 11 April 2012 Indian Ocean Earthquakes, Paul, J., K. Rajendran and C.P. Rajendran, Bulletin of the Seismological Society of America, May 2014

Andaman postseismic deformation observations: Still slipping after all these years, Paul, J., C.P. Rajendran, A.R. Lowry, V. Andrade and K. Rajendran, Bulletin of the Seismological Society of America, Vol. 102, No. 1, pp. 343–351, February 2012, doi: 10.1785/0120110074

Significant Motions between GPS Sites in the New Madrid Region: Implications for Seismic Hazard, Frankel, A., R Smalley Jr, and J. Paul, Bulletin of the Seismological Society of America, Vol. 102, No. 2, pp. 479–489, April 2012, doi: 10.1785/0120100219

Postseismic deformation of the Andaman Islands following the 26 December, 2004 Great Sumatra–Andaman earthquake, Paul, J., A. R. Lowry, R. Bilham, S. Sen, and R. Smalley Jr. (2007), Geophys. Res. Lett., 34, L19309, doi:10.1029/2007GL031024.

Geodetic detection of active deformation in the New Madrid seismic zone, Smalley, F. Jr., M.A. Ellis, J. Paul, Seis. Res. Lett, 77, 1, 105, 2006

Post seismic Deformation in the Central Andaman Islands, Paul, J., Smalley, R., Jr., Bilham, R., Lowry, A. and Batacharjee, A., AGU 2005 Eos Trans. AGU, 86(52), Fall Meet. Suppl., Abstract U11B-0838

Post-seismic deformation of Andaman Islands since the 2004 earthquake, Paul, J., Lowry, A., Bilham, R., Sen, S., Sharma, T.V.R.S., and Smalley, R., Jr., (2006), Title, Eos Trans. AGU, 87(52), Fall Meet. Suppl., Abstract U53A-0037

Three years of post seismic deformation of Central Andaman Islands, Paul, J., Lowry, A., Bilham, R., and Sen, S., Eos Trans. AGU, 88(52), Fall Meet. Suppl., Abstract G13A-0909

Space geodetic evidence for rapid strain rates in the New Madrid seismic zone, central USA, Smalley, R., Jr., Ellis, M. A., Paul, J. and Arsdale, R. V., Nature, 453, 23, 1088-1090, 2005.

The motion and active deformation of India. Geophys. Res. Lett. Vol. 28 , No. 04 , p. 647 ; Paul, J. ; Burgmann, R. ; Gaur, V. K. Bilham, R. ; Larson, K. M. ; Ananda, M. B. ; Jade, S. ; Mukul, M. ; Anupama, T. S. ; Satyal, G. ; Kumar, D. 2001

Global Positioning System measurements of the Indian Plate motion and Convergence across the lesser Himalaya, Geophysical Research Letters,23, pages 3107-3110, 1996, Freymueller, J. ; Bilham, R. ; Bürgmann, R. ; Larson, K. M. ; Paul, J. ; Gaur, V. 1996 Microstrain stability of Peninsular India 1864-1994, Proc Indian Acad.Sci.(Earth Planet Sci.), 104, No.1, pages 131-146, 1995, Paul et al., 1995

Modelling of the gravity effects of flexurally compensating thin layers under Afanasy - Nikitin seamount. Paul, J., and Singh, R.N., Tectonophysics, 206 (1992) 365-369.


Emplacement of Afanasy-Nikitin seamount based on transfer function analysis of gravity and bathymetry data. Earth Planet. Sci. Lett., 96, 419 – 426, Paul, J., Singh, R.N., Subrahmanyam, C., and Drolia, R.K. 1990

Uplifted new beach/corals of North Sentinel (Movie)

Uplifted corals of North Sentinel (Image)

Subsidence at Sipighat near Port Blair(Movie)

 100 yr old jail that stood firm during 2004 earthquake(Movie)

On the way to a GPS site in Andaman Islands

Site Code Site Description Longitude Latitude  
MHRT Mt. Hariot - Campaign 92.733 11.721 Picture
PBL2 Port Blair - Continuous 92.720 11.614 Picture
HAVE Havelock - Campaign 93.016 11.982 Picture
WNDR Wandoor - Campaign 92.621 11.601 Picture
RUTL Rutland - Campaign 92.651 11.488 Picture
RMNG Ramnagar - Campaign 93.035 13.079 Picture
JBNK Rangachang - Campaign 92.739 11.570 Picture
RUSW Rutland SW - Campaign 92.588 11.401 Picture
HAV2 Havelock - Continuous 92.980 12.035 Picture
INTV Interview Is - Campaign 92.667 12.898 Picture
SMTH Smith Is - Campaign 93.060 13.278 Picture
KMOR Kamorta - Campaign 93.540  08.055   Picture  
LAND Hutbay - Continuous 92.750  10.530  Picture  
RNGT Rangat - Continuous 92.906  12.513  Picture  

Who we are and what we do

3890 Central Ave | Memphis TN 38152 | 901-678-2007