This Small Grant for Exploratory Research supports reconnaissance surveys of the December 26, 2004 Great Sumatran earthquake and tsunami. The 2004 Sumatran earthquake and tsunami has caused waves in excess of 10m in Thailand and Indonesia, in excess of 5m in Sri Lanka and India, and it has impacted the Maldives, Kenya, Tasmania and Somalia. The tsunami waves affected the near source region of Northern Sumatra, Indonesia and the Andaman and Nicobar Islands almost immediately while taking approximately 1.5 hours to reach the shores of Myanmar and Thailand to the east, and 2 to 3 hours to reach India, Sri Lanka and the Maldives to the west. Given the geographic extent of the affected area, it is necessary to focus the surveys on select areas of interest, which will then guide later more comprehensive surveys.
The intellectual merit of this work lies in the fact that tsunami field surveys allow for quantitative measurements of tsunami inundation of a specific event. The measurements are based on observations of watermarks and eyewitness accounts to help understand arrival times and infer tsunami currents. This is the first transoceanic tsunami since 1964, and the geographical distribution of inundation in SE Asia, Indian Subcontinent and Africa will help better understand tsunami generation and the associated seismological parameters. For comparison, the tsunamis of 1992-2004 surveyed with NSF funds have had local impact and limited geographic extend, yet our understanding of tsunami generation and effects has increased dramatically through the direct application of field data to numerical modeling efforts (Synolakis et al., 2002, Borrero et al., 2003)
The broader impact of the survey extends beyond gathering and documenting inundation data and developing inundation models. Every NSF tsunami survey includes public outreach. As they have done in the past, survey scientists will make presentations in schools, civil defense and emergency management and other government officials to explain the mechanics of tsunami generation, the occurrence of tsunamis, and the experience with tsunami hazards mitigation elsewhere in the world. Most importantly they discuss by reference to tsunami impacts elsewhere that every coastal resident should know that if they feel an earthquake and/or observe unusual water motions such as rapid withdrawal or forward motion of the shoreline, they should immediately move to high ground or inland. A further broader impact of the data collected is its use in developing and validating new tsunami inundation models and in using these models in assessing risk from future tsunamis in the Indian Ocean and elsewhere. Modeling efforts currently under way for the Cascadia Subduction Zone (CSZ) will benefit directly from the data collected during these surveys and those results will directly impact the production of tsunami inundation and hazard maps for the states of California, Oregon, Washington and Hawaii.
