The Sumatra Earthquake and Tsunami Offshore Survey (SEATOS) investigated the seafloor area near the 26 December 2004 earthquake. An early look at the data suggests that only small ground motions occurred. This raises major questions about how the enormous amount of energy from that earthquake could dissipate over relatively short distances, and whether the ground motion is characteristic of other active margins.

SEATOS, which included an international, interdisciplinary team of scientists, conducted a detailed seafloor expedition in the vicinity of the epicenter of the Great Sumatra earthquake, in May 2005. The success of this interdisciplinary effort has led to a follow-on workshop and a Union session at the upcoming AGU Fall Meeting on 5–6 December in San Francisco.