On December 26, 2004, my wife and I were on vacation in a hotel on the SW coast of Sri Lanka. Despite being in the shadow of the island from the Sumatran earthquake, the tsunami devastated the ground floor of the hotel. Although full details of the tsunami generation and propagation are complicated, many of our observations are easily understood using simple applied mathematics and special functions. The long wavelength waves were diffracted around the south of the island resulting in significant long-shore currents between the waves. The Green function for tsunami generation, propagation and dispersion in a deep, uniform ocean is described by the Airy function which accurately predicted the arrival time in Sri Lanka. Nevertheless, the dispersed waveform of the Airy function in no way matches our observations of the periods of the main waves. The observed waveforms reflect the geometry of the source mechanism, and the observed wavelengths immediately indicate the huge area of seafloor uplift. The seafloor discontinuity caused by the source fault is dispersed during propagation and is described by the Airy function. In this talk I’ll recall our personal experiences and outline how the basic theory of tsunami propagation explains our observations.
Chapman, C.H., “The Asian Tsunami in Sri Lanka: a personal experience”, EOS, 86, 2, 13-14, (11 January 2005) (http://www.agu.org/eos_elec.000929e1.html; http://www.agu.org/eos_elec.000929e2.html); Tamil Times, 24, 1, 19-24 (January 2005); (interview) Nature, 433, 7024, 354 (27 January 2005) (http://www.nature.com/news/2005/050124/full/433354a.html); Leading Edge, 24, 2, 124-125 (February 2005)