RESEARCH COMMUNICATIONS CURRENT SCIENCE, VOL. 89, NO. 1, 10 JULY 2005 195 *For correspondence. (e-mail: chandran@ns.annauniv.edu) azimuthal anisotropy of the Australian upper mantle. Geophys. J. Int., 2002, 151, 738–754. 36. Lowry, A. R. and Smith, R. B., Strength and rheology of the western US Cordillera. J. Geophys. Res., 1995, 100, 17947–17963. 37. Menon, R., Kumar, P. S., Reddy, G. K. and Srinivasan, R., Radio- genic heat-production of Late Archaean Bundelkhand granite and some Proterozoic gneisses and granitoids of central India. Curr. Sci., 2003, 85, 634–638. 38. Roy, S. and Rao, R. U. M., Heat flow in the Indian shield. J. Geo- phys. Res., 2000, 105, 25587–25604. 39. Stephen, J. and Singh, S. B., Correlation of effective elastic thickness and seismogenic thickness in the continental lithosphere of India. Eos Trans. AGU, 2004, 85, (17), Joint Assembly Suppl., JA446. ACKNOWLEDGEMENTS. We thank Dr V. P. Dimri, Director, NGRI for permission and encouragement to publish this work. We also thank Dr U. Raval for useful discussions. Received 13 August 2004; revised accepted 17 February 2005 Ecological impact of tsunami on Nicobar Islands (Camorta, Katchal, Nancowry and Trinkat) S. Ramachandran*, S. Anitha, V. Balamurugan, K. Dharanirajan, K. Ezhil Vendhan, Marie Irene Preeti Divien, A. Senthil Vel, I. Sujjahad Hussain and A. Udayaraj Institute for Ocean Management, Anna University, Chennai 600 025, India Assessment of tsunami-inflicted damage to island eco- systems assumes great importance owing to the life- sustaining and livelihood support abilities of the eco- systems. Apart from damages caused to life and property, significant damages were caused to ecosystems, which will have long-lasting effects. The tsunami-induced damage to coastal ecosystems was studied in four Nicobar Islands, viz. Camorta, Katchal, Nancowry and Trinkat. The extent of damages assessed ranged from 51 to 100% for mangrove ecosystems, 41 to 100% for coral reef ecosystems and 6.5 to 27% for forest ecosystems. The severity of damages and their consequences suggest the need for a definite restoration ecology programme. TSUNAMIS are water waves generated by the disturbance associated with seismic activity, explosive volcanism, submarine landslide, meteorite impact with the ocean, or in some cases meteorological phenomena. These waves can be generated in oceans, bays, lakes or reservoirs. The term ‘tsu- nami’ in Japanese means harbour (tsun) wave (ami) 1 . The earthquake on 26 December 2004 with its epicentre at Suma- tra, Indonesia triggered a tsunami which had a major impact on the Andaman and Nicobar Islands. The massive tsunami swept through the Indian Ocean region to become arguably the largest natural disaster in living memory. Initial reports indicate that natural ecological systems such as coral reefs, mangroves and wetlands have suffered extensive damages. This calamity highlights the key protective role of coral reefs, mangroves and the importance of CRZ (Coastal Regulation Zone) Notification. Physical damages might impact the structure and function of coastal ecosystems and their ability to sustain marine life and support livelihood of coastal communities. The extent of damage caused to coastal ecosys- tems and communities in Camorta, Katchal, Nancowry and Trinkat Islands is studied using remote sensing and GIS tools. Ecological impacts of tsunami are not available from previous scientific literature. This communication reports first-hand assessment of ecological damages caused by the December 2004 tsunami in some Nicobar Islands. The Nicobar Islands are situated southeast of the Bay of Bengal. There are altogether 22 large and small islands, out of which only twelve have inhabitants. The latitudes and longitudes of the four islands under study are as follows: Camorta 7°59′12″–8°14′43″N, 93°25′49″–93°34′36″E, Kat- chal 7°51′50″–8°01′56″N, 93°17′41″–93°28′47″E, Nan- cowry 7°55′04″–8°01′57″N, 93°29′23″–93°35′01″E, and Trinkat 8°01′45″–8°08′48″N, 93°37′04″–93°37′30″E. Nan- cowry and Camorta have a hilly terrain covered with grass, forming undulating meadows. In Camorta, Empress Peak is the highest peak, about 1.420 ft high. Katchal is one of the largest islands in the central group. It is about 61 sq miles in area. It is slightly hilly at the centre, but other- wise it is remarkably flat. Trinkat is another small flat is- Base map SOI Toposheet Satellite data IRS P6 AWiFS (2004 and 2005) Multi-date land-use/ land-cover map Visual interpretation Onscreen digitization Input into GIS Ancillary data Overlay analysis Identification of land-use/ land-cover changes and generating statistics Figure 1. Methodology for land-use/land-cover mapping.