This work examines the extent to which tsunami forecasts from different numerical forecast systems might be expected to differ under real-time conditions. This is done through comparing tsunami amplitudes from a number of existing tsunami scenario databases for eight different hypothetical tsunami events within the Indian Ocean. Forecasts of maximum tsunami amplitude are examined at ten output points distributed throughout the Indian Ocean at a range of depths.The results show that there is considerable variability in the forecasts and on average, the standard deviation of the maximum amplitudes is approximately 62% of the mean value. It is also shown that a significant portion of this diversity can be attributed to the different lengths of the scenario time series. These results have implications for the interoperability of Regional Tsunami Service Providers in the Indian Ocean.

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The Indian Tsunami Early Warning System situated at Indian National Center for Ocean Information Services, Hyderabad, India, monitors real-time earthquake activity throughout the Indian Ocean to evaluate potential tsunamigenic earthquakes. The functions of the Indian Tsunami Early Warning System earthquake monitoring system include detection, location and determination of the magnitude of potentially tsunamigenic earthquakes occurring in the Indian Ocean. The real-time seismic monitoring network comprises 17 broadband Indian seismic stations transmitting real-time earthquake data through VSAT communication to the central receiving stations located at the Indian Meteorological Department, New Delhi, and the Indian National Center for Ocean Information Services, Hyderabad, simultaneously for processing and interpretation. In addition to this, earthquake data from around 300 global seismic stations are also received at the Indian National Center for Ocean Information Services in near-real-time. Most of these data are provided by IRIS Global Seismographic Network and GEOFON Extended Virtual Network through Internet. The Indian National Center for Ocean Information Services uses SeisComP3 software for auto-location of earthquake parameters (location, magnitude, focal depth and origin time). All earthquakes of Mw >5.0 are auto-located within 5-10 minutes of the occurrence of the earthquake. Since its inception in October 2007 to date, the warning centre has monitored and reported 55 tsunamigenic earthquakes (under-sea and near coast earthquakes of magnitude ⩾6.5) in the Indian Ocean region. Comparison of the earthquake parameters (elapsed time, magnitude, focal depth and location) estimated by the Indian Tsunami Early Warning System with the US Geological Survey suggests that the Indian Tsunami Early Warning System is performing well and has achieved the target set up by the Intergovernmental Oceanographic Commission.

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