In this paper, we report that the ratio of broadband energy (0.01–2 Hz) to high-frequency energy (0.3–2 Hz), E <Subscript>r</Subscript>, estimated from regional seismograms of India, might be a useful parameter in estimating tsunami potential of earthquakes in the Sumatra–Andaman region. E <Subscript>r</Subscript> is expected to be sensitive to the depth as well as to the source characteristics of an earthquake. Since a shallow and slow earthquake has a greater tsunamigenic potential, E <Subscript>r</Subscript> may be a useful diagnostic parameter. We base our analysis on broadband seismograms of the great earthquakes of Sumatra–Andaman (2004, M <Subscript>w</Subscript> ~ 9.2) and Nias (2005, M <Subscript>w</Subscript> 8.6), 41 of their aftershocks, and the earthquakes of north Sumatra (2010, M <Subscript>w</Subscript> 7.8) and Nicobar (2010, M <Subscript>w</Subscript> 7.4) recorded at VISK, a station located on the east coast of India. In the analysis, we also included the two recent, great strike-slip earthquakes of north Sumatra (2012, M <Subscript>w</Subscript> 8.6, 8.2) recorded at VISK and three south Sumatra earthquakes (2007, M <Subscript>w</Subscript> 8.5; 2007, M <Subscript>w</Subscript> 7.9; 2010, M <Subscript>w</Subscript> 7.8) recorded at PALK, a station in Sri Lanka. We find that E <Subscript>r</Subscript> is a function of depth; shallower earthquakes have higher E <Subscript>r</Subscript> values than the deeper ones. Thus, E <Subscript>r</Subscript> may be indicative of tsunamigenic potential of an earthquake. As M <Subscript>w</Subscript> and E <Subscript>r</Subscript> increase so does the tsunami potential. In addition to the parameter E <Subscript>r</Subscript>, the radiated seismic energy, E <Subscript>s</Subscript>, may be estimated from the regional seismograms in India using empirical Green’s function technique. The technique yields reliable E <Subscript>s</Subscript> for the great Sumatra and Nias earthquakes. E <Subscript>r</Subscript> and E <Subscript>s</Subscript> computed from VISK data, along with M <Subscript>w</Subscript> and focal mechanism, may be useful in estimating tsunami potential along the east coast of India from earthquakes in the Sumatra–Andaman region in less than ~20 min. Copyright Springer Science+Business Media B.V. 2012
