The Indian Ocean disaster: Tsunami physics and early warning dilemmas



Understanding the physics of tsunamis may save lives, especially near the epicenter of a large earthquake where the danger is highest and early warning is least likely to be effective.

Normal modes of Earth are standing waves of the Love (toroidal) or the Rayleigh (spheroidal) variety. The Indian Ocean tsunami may have been partly or wholly caused by low-order spheroidal modes of the Earth such as 0S2, 0S3, and 0S4, that may have excited a waveguide—a layer that confines and guides a propagating wave—in the ocean.